Interoperability middleware for OPeNDAP clients to discover data cataloged in OGC data catalogs
Author(s):
Min Min;
Liping Di;
Wenli Yang;
Peng Yue
Show Abstract
Successful data sharing is important to integrating information between the Earth Science and geographic information
communities for knowledge discovery. The Open-source Project for a Network Data Access Protocol (OPeNDAP) is a
data transport architecture and protocol widely used by earth scientists. However, because the DAP and OGC protocols
are incompatible. OPeNDAP lacks effective tools to access the OGC data. To solve this problem, middleware between
the OGC and DAP protocols, must perform two functions--data discovery and data access. This paper discusses
implementation of the data discovery component. This data discovery component first converts an OGC catalog to a
THREDDS catalog encoded in XML, and then provides the XML file to the OPeNDAP client. By developing a catalog
component of the middleware, the implementation enables OPeNDAP clients to discover data cataloged in OGC data
catalogs.
An improved model with bending of laser beam for satellite-to-ground AO laser communication
Author(s):
Jian Rong;
Fang Li;
Xiao-chun Zhong;
Xue-ke Ding;
Guan Gui
Show Abstract
Correcting scintillation for a slant path with adaptive optics (AO) has been studied. However, the models for solving this
problem are all to treat the ray track as a straight line. Based on the engineering practical environment, in a
low-earth-orbit (LEO) satellite-to-ground laser communication link, the properties of laser beam bending in the slant
path will be studied in this paper, and the novel amendatory model of correcting the scintillation with AO will be
presented.
A new routing method based on ant colony algorithm for LEO satellite communication networks
Author(s):
Ying Wang;
Xiulin Hu
Show Abstract
LEO(Low Earth Orbit) satellite network is more suitable for multimedia communication than GEO(Geosynchronous
Earth Orbit) and MEO(Medium Earth Orbit) satellite network because of short propagation delay. Routing computation
in communication network with several constraint factors has been proved to be a NP-C problem. Ant colony algorithm
as a bionics algorithm has good performances on solving NP-C problem. Existing research about ant colony algorithm
mainly concentrates on Ad hoc network, and application in satellite network is not completely developed. According to
the characteristics of LEO satellite network, this paper presents a new routing method based on ant colony algorithm
with forecast strategy and elitist strategy. Generally each satellite establishes two intra-ISLs with forward and backward
neighbors in the same orbit, and two inter-ISLs with left and right neighbors in the adjacent orbits. Thus the topology of
satellite network consists of many grids. According to the specific topology, forecast strategy is introduced to reduce
redundant information. On the other hand, pheromone is updated continuously to ensure elitist path chosen. Assuming a
reference satellite network model is given, the simulation results show that the improved algorithm converges more
quickly than basic ant colony algorithm.
Application of Turbo code in satellite-ground laser communication and analysis on its effectiveness
Author(s):
Fu Sun;
Xuhua Zhai;
Jingfeng Zang;
Lu Song;
Fuchang Yin
Show Abstract
Satellite-ground laser communication system based on Turbo code is put forward and analyzed. Firstly, this paper
analyzes channel character, then simulates the characteristic of the system based on Turbo code. The result shows that
Turbo code can well compensate and conquer all kinds of attenuations and noises. So the bit error rate is reduced. In
addition, anti-jamming ability, stability and reliability are improved.
Time domain characteristics of UWB signal transmitting through a finitely conducting slab
Author(s):
Yang Wang;
Naitong Zhang;
Qinyu Zhang;
Zhongzhao Zhang
Show Abstract
A new approximate time domain reflection coefficient, the relationship between the reflection and refraction on slab
surfaces, and expression for propagation loss term within the slab in time domain are deduced in this paper. By using
time domain convolution of the three terms, a simplified analytic solution for UWB impulse signal transmitting through
a finitely conducting slab is proposed. This solution takes into account the frequency range from 3.1 to 10.6 GHz and is
suitable for most common building construction materials within indoor environment. The simulations of incident
monocycle transmitting through slabs of different materials and thickness are presented by applying the simplified time
domain analytic solution to illustrate the characteristics of transmission and give some results in simplification of
transmission field analysis in indoor channel modeling.
An efficient approach for adaptive multibeam forming algorithm
Author(s):
Ji Yu;
Jun Tang;
Yingning Peng
Show Abstract
Due to the fast beam-steering and adaptive interference suppression performance, adaptive digital beamforming (ADBF)
technique is widely used in the multi-antenna radar systems, such as phased array radar and MIMO radar, which are
important measurements of space target surveillance system. However, the use of adaptive digital beamforming
techniques in multiple beamforming (MBF) system is restricted by the computational requirement as the number of beam
increases, especially in the spaced-based system. A fast MBF algorithm is presented in this paper. The algorithm
rearranges the process of beamforming, which reduces the computational complexity by the utilization of FFT and the
fast chirp z-transform (CZT) method while remaining the same performance of conventional methods. The
computational cost analysis and simulation results show that the algorithm needs less computational requirement than
that of direct approach without harming the adaptive interference suppression performance.
Performance research of multiple access of satellite formation flying laser communication in atmospheric turbulence
Author(s):
Yongjun Li;
Shanghong Zhao;
Jili Wu;
Guoliang Dai;
Jie Xu
Show Abstract
A novel multiple access model of satellite formation flying is brought forward, which has the advantages of shared signal
bandwidth, asynchronous access etc, at the same time it overcomes the problems of difficulty of constructing the
addressing codes in the optical code division multiple access and that of hardware implementing in wavelength division
multiple access. The model makes use of delay difference between two arms of Mach-Zender interferometer (MZI) to
encode and decode at the end of transmitter and receiver respectively, that's to say when the delay difference of
receiving end is close to that of transmitting end, the received optical power would be maximum. Frequency shift keying
modulation is adopted to achieve the coherent multiplexing multiple access. Then when the micro-satellite beam is
transmitted in atmosphere condition of weak turbulence, the receiving optical field is described by the Rytov model
based on the premise of independent optical field interference, the formula of SNR and BER is deduced. The simulation
results show that given the turbulence amplitude, 1/SNR ascends along with increasing of satellite number, furthermore
the larger turbulence amplitude, the more quickly 1/SNR rises, this proves number of satellites and turbulence amplitude
are the dominating parameters which affect the system performance.
Research on dynamic bandwidth allocation simulation for the space network
Author(s):
Ning He;
Lei Wang;
Yu Lu
Show Abstract
In this paper, the characteristic of satellite network is analyzed, and based on perturbation analysis, a dynamic bandwidth
allocation model is put forward. Based on this model, the bandwidth event path is established, the process of the
perturbation spread is analyzed and the bandwidth sensitivity about average transport delay of the space network is given.
The paper lays a foundation of decrease of average transport delay and enhancement of performance of the space
network.
Dual header pulse interval modulation (DH-PIM) in FSO communications
Author(s):
Tianping Deng;
Kai Peng;
Yimin Lu;
Gang Lu
Show Abstract
Recently, free space optical communication has attracted a considerable amount of interest as an alternative medium to
radio for wireless transmission. It has many advantages such as a huge unregulated bandwidth, high data rates, and
resistance to multi-path fading relative security against eavesdropping. The work presented in this thesis focuses on
modulation schemes. Concerns of eye safety and power consumption limit the average transmitter power, which suggests
that modulation techniques possessing a high peak-to-mean power ratio are favorable. This is generally achieved by
trading off power efficiency against bandwidth efficiency. A novel dual-header pulse interval modulation (DH-PIM) for
optical wireless communications is proposed in this paper. The symbol structure, the spectral properties, and the
expression for bandwidth requirement and optical power requirement of DH-PIM in the absence of and in the presence
of multi-path dispersion is presented in this paper.
Design and real-time simulation of high-altitude/long-endurance airship flight control system
Author(s):
Zhongjian Li;
Mei Wu
Show Abstract
In recent years, high-altitude/long-endurance (HALE) airship platforms have generated great interest as a means to
provide communications and surveillance capabilities using a relatively inexpensive flight platform. One of the
challenges of HALE airship design is the development of flight control system. Modeling, flight control law design and
real-time simulation platform construction for a conceptual high altitude long endurance airship are studied in this paper.
The nonlinear six degree-of-freedom (DOF) dynamic equations of the airship with added mass and inertia are developed
using Matlab, and linear models are extracted from it. Flight control laws are designed for geostationary positioning. A
real-time open architecture flight simulation system was developed using commercial-off-the-shelf hardware and popular
software. By using automatic code generate technique, the system drastically reduced expenses for high-fidelity simulations
without abandoning quality. The simulation system is flexible enough to allow expansion and reconfiguration and later
can accomplish hardware-in-the-loop (HIL) simulation.
Network coded partner selection between cooperative nodes in air-based wireless networks
Author(s):
Bing Du;
Jun Zhang;
Rui Xue
Show Abstract
This paper presents a selection and grouping algorithm based on proposed network coded cooperative strategy in
aeronautical communications. In such a practical scenarios, communications between high-speed mobile nodes are
troubled with high reliability and capacity demands of the emerging aeronautical applications. The idea of network
coded cooperative strategy is combining information at the relay and joint decoding at the destination, which could
improve reliability and capacity without much loss of throughput of the whole networks. Then, we consider the selection
and grouping algorithms in this context. An adjacency matrix is defined to describe the connection of the nodes in one
radio contact disk, so that, the selection and grouping algorithm is equal to construct this adjacency matrix avoiding girth
4 and minimize the system outage probability. At the end of the paper, simulations and results will be given to
demonstrate the algorithms.
Laser spot detection and characteristic analysis in space optical communication
Author(s):
Jin Duan;
Chuiliu Kong;
Wenbo Jing;
Dan Zhang;
Huilin Jiang
Show Abstract
In the space laser communication, the link of communication is builded in atmospheric random channel. the laser
transmission is affected by the atmospheric turbulence seriously. The communication laser is modulated to circular
polarized light in order to reduce the influence of the atmospheric turbulence. A several experiments are designed to
validate that the circular polarized laser is available to reduce the communication noise in the space optical
communication. The methods of the laser spot detection and spot parameter analysis is put forward in this paper: Firstly
the subtraction of the background is used in image preprocessing in order to eliminate the influence of static background,
then a series of methods such as the local dynamic threshold segmentation, edge extraction are used to detect and
recognize the spot. Finally the parameters of the spot are calculated such as spot's average brightness, background's
average brightness and the contrast gradient, and the characteristic of the laser communication is analyzed. The
experiment results show that the circular polarized laser can enhance the contrast and improve the communication
quality in the spatial optical communication. This method satisfies the request of real-time processing in communication,
and is also effective and practical. practical.
Stereo vision for spacecraft formation flying relative navigation
Author(s):
Weifeng Liu;
Long Han
Show Abstract
First this paper describes the principals of stereo vision, the application in spacecraft formation flying and deduces the
formulations for the observation. Then a kalman filter enhanced vision system for spacecraft formation flying relative
navigation is discussed. At last some virtual evaluations for proposed measurement is presented which showed the better
stability and precision.
Research on low-latency MAC protocols for wireless sensor networks
Author(s):
Chenguang He;
Xuejun Sha;
Chankil Lee
Show Abstract
Energy-efficient should not be the only design goal in MAC protocols for wireless sensor networks, which involve the
use of battery-operated computing and sensing devices. Low-latency operation becomes the same important as energy-efficient
in the case that the traffic load is very heavy or the real-time constrain is used in applications like tracking or
locating. This paper introduces some causes of traditional time delays which are inherent in a multi-hops network using
existing WSN MAC protocols, illuminates the importance of low-latency MAC design for wireless sensor networks, and
presents three MACs as examples of low-latency protocols designed specially for sleep delay, wait delay and wakeup
delay in wireless sensor networks, respectively. The paper also discusses design trade-offs with emphasis on low-latency
and points out their advantages and disadvantages, together with some design considerations and suggestions for MAC
protocols for future applications and researches.
A memory cost improved bandwidth request algorithm in DVB-RCS
Author(s):
Jian He;
Zulin Wang
Show Abstract
The Bandwidth request algorithm which intervenes in the bandwidth-on-demand (BoD) access mechanism plays an
important role in DVB-RCS satellite systems to optimize bandwidth utilization. In this paper, a memory cost improved
bandwidth request algorithm (MCI-BRA) is proposed. The MCI-BRA deals mainly with the memory cost which is
measured as the queue size at the terminal while offers a controllable trade-off between delay and efficiency. A traffic
plane model for a satellite system using DVB-RCS is also described. Several assumptions are discussed, followed by
detailed description of the MCI-BRA. Comparisons between the proposed algorithm and existing ones are also presented
and analyzed. The simulating results show that MCI-BRA proposed in this work performs better than existing algorithms
on controlling memory cost while handles the delay and efficiency issues as well as the existing ones.
Pivotal technology in UWB wireless communications
Author(s):
Qiang Hou;
Guo-ping Wu;
Ying Huang;
Li Fan
Show Abstract
The emerging technology of ultra wide-band (UWB) high-speed indoor wireless communication has attracted worldwide
attention. With the merits of high data rate, low system power cost and mufti-path immunity, compared with general
narrow band wireless communication systems, UWB has became one of the most competitive and promising
technologies in the near future. Theoretical researches and simulation experiments are done in this paper about a few of
key problems in UWB wireless communication of channel measurements and modeling indoor wireless channel and
performance evaluation of space hopping UWB Impulse Radio (SH-UWB-IR) System.
Free space quantum system based on quantum secure direct communication
Author(s):
Hua Ge;
Wenyu Liu
Show Abstract
A new practical free space quantum communication system is proposed, it is based on the principle of quantum secure
direct communication. Quantum cryptography is a practical method to realize free space optical communication.
Different from the existing free space quantum key distribution communication system, the free space quantum secure
direct communication is deterministic and the system is more simple. In this paper, a new structure of four transmitting
channels is prensented, this structure could increase the security and capacity of system. The setup of transmitter and
receiver of each transmitting channel is discussed in detail, and the communication process is analyzed. The result shows
that this free space quantum system could be realized and can work over long distance.
The study of an ATM switch system used for on-board processing
Author(s):
Yong Li;
Huibo Xiong
Show Abstract
On-board processing (OBP) is one of significant satellite communication technologies, and the Asynchronous Transfer
Mode (ATM) is widely used in the OBP which can guarantee the QoS. This article presents the CAC (Call Admission
Control) algorithm and Congestion Control algorithm. We combine with B-CAC algorithm, Bahadur-Rao's theory, Weiss
theory, to improve the old method, and the simulation results show that when the PDR/LR is small the burst is high, the
chain utilization and statistic multiplexing gain get a big advantage. Besides, concerning TCP congestion control, the
article compared five strategies: Tahoe, Reno, Newreno, Sack and Vegas. The simulation results show that the Vegas can
be used to predict congestion conditions correctly; its congestion window (cwnd) control is smoother and is superior to
other algorithms in average RTT.
Data bus of on-board data system for micro-small satellite
Author(s):
Bin Li;
Youjun Liu
Show Abstract
Modularized design takes great advantage to micro-small satellites. Many modules and subsystems are manufactured
individually, needs a distributed on-board data system. A kind of distributed OBDS is carried out, all the modules and
subsystems connect to data bus network by ESN. Many kinds of bus can be used in satellite, and CAN, UART and
802.11 represents three typical different kind. The ESN structure is given. Take CAN bus for example, the paper details
the process of bus initialization, noting some facts for PnP function.
Study on correcting angle-of-arrival fluctuations of space optical communication with AO
Author(s):
Fang Li;
Jian Rong;
Xiao-chun Zhong;
Xue-ke Ding
Show Abstract
The method of correcting angle-of-arrival fluctuations with adaptive optics (AO) is presented in this article. Numerical
simulation is used for analyzing and studying the effect of AO correction and its influence factors. The simulative
results indicate that AO can correct angle-of-arrival fluctuations induced by atmosphere turbulence effectively and the
effect of AO correction is related with wavelength and aperture.
A new algorithm of BOC multipath error simulation
Author(s):
Qiang Li;
Huifeng Li;
Bing Liu
Show Abstract
European GALILEO different from GPS will have more excellent positioning performance in accuracy for that a new
modulation technique which is called the Binary Offset Carrier (BOC) modulation will be adopted in GALILEO. BOC
modulation has a direct high efficiency in frequency occupation and in mitigation of interference. In the pseudo range
measurement for high precision application, code tracking multipath error is one of the main error sources that can not be
eliminated by Differential Global Positioning System(DGPS), and many testing and measuring results have shown that
code tracking multipath error has become a dominating error source in the future Global Navigation Satellite System
(GNSS) applications. This paper presents the code tracking multipath error of BOC signals in GALILEO and of L1
signal in GPS after analysis of several characteristics in time and frequency domain such as AutoCorrelation Function
(ACF) and Power Spectral Density (PSD). The conventional ACF of GPS signals is expressed by the triangle shaped
function, but the BOC signals have ACF with multiple peaks that result in the complexity of ACF expression in many
intervals. This paper presents another expression with the ceil function to compute the theoretical code tracking
multipath error for sine typed and cosine typed BOC signals. Compared with the traditional algorithm, the new algorithm
can speed up the numerical solution of the tracking bias in simulation. The simulation results indicate that the
antimultipatherror performance of cosine BOC signals is much better than that of sine BOC signals.
P2PQR-tree: a spatial index model for peer-to-peer environments
Author(s):
Chuanbo Chen;
Degang Liu;
Baolin Yi
Show Abstract
It is necessary to build spatial index in order to managing complex spatial data in peer-to-peer (P2P) environments. This
paper analysis and summarizes the related studies, designs a new spatial index model named P2PQR-tree which uses the
distributed Quad-tree and the local R*-tree. P2PQR-tree applies Quad-tree techniques into P2P environments and uses
replication strategy to improve the system's load balance. This paper includes gives the models definitions, the model's
architecture design, the model's performance analysis results. P2PQR-tree has some advantages to the old methods, for
example, its data management is more reasonable, it can support metadata management better, implement rights control
easier, reduce changes of distributed index, and adapt to dynamic character of P2P network better.
A new approach for modulation recognition based on ant colony algorithm
Author(s):
Shu Liu;
Hongyuan Wang
Show Abstract
A New Approach based on ant colony algorithm for the automatic modulation recognition of communications signals is
presented. This approach can discriminate between continuous wave (CW), Amplitude Modulation (AM), Frequency
Modulation (FM), Frequency Shift Keying (FSK), Binary Phase Shift Keying (BPSK) and Quaternary Phase Shift
Keying (QPSK) modulations. Requirements for a priori knowledge of the signals are minimized by the inclusion of an
efficient carrier frequency estimator and low sensitivity to variations in the sampling epochs. Computer simulations
indicate good performance on an AWGN channel, even at signal-to-noise ratios as low as 5 dB. This compares favorably
with the performance obtained with most algorithms based on pattern recognition techniques.
A non-interactive and efficient key agreement protocol for ASNs
Author(s):
Deming Yang;
Dejun Mu;
Zhong Xu
Show Abstract
Ad hoc space networks (ASNs) are implemented using flexible, distributed architecture consisting of constellations of
dynamically deployed space, airborne and mobile platforms. The nodes within ASNs operate both as communication
end-points as well as routers, enabling multi-hop wireless communication and dynamic network topology. Secure and
efficient key agreement scheme is the crucial mechanism to construct secure ASNs. Previous ID-based cryptosystem is
not feasible in ASNs because of the interaction process in key agreement. A novel non-interactive and efficient ID-based
two-party key agreement protocol is proposed for ASNs. Based on the security analysis of IDNIKS proposed by Tso et
al., the feasibility of adopting non-interactive key agreement for multi-party in ASNs is analyzed and a conclusion is
given.
Design of bus-on-chip core for micro-satellite avionics
Author(s):
Youjun Liu;
Zheng You;
Bin Li;
Xiangqi Zhang;
Ziyang Meng
Show Abstract
This paper discusses a layout of bus-on-chip core referring to SoC thinking which is composed of six sections based on a
physical chip of FPGA: multi-Processor cache coherence unit, external bus control module, TT&C module, Ethernet
Mac interface, EDAC/DMA module, and AMBA bridges. Multi-processor cache coherence unit, as a key part of the bus
core, is used to serve the rapid parallel computing by means of the breakthrough of write/read speed of EMS memory
and enhances the reliability of OBC with the service of supporting the hot standby of redundancy and the reconfiguration
of fault-tolerance. External bus control module is made to support the PnP of external components applying varieties of
buses, which is designed by means of soft-core in order to adapt the variation of macro-design and improve the
flexibility of external application. TT&C module is the interface of subsystems of telemetry, telecommand and
communication, which involves the protocols of HDLC. Ethernet Mac interface based on TCP/IP acts as the access of
ISL for formation flying, constellation, etc. EDAC/DMA module mainly manages the data exchange between AMBA
bus and RAM, and assigns DMA for the payloads.
Novel multi-satellite transmit diversity schemes
Author(s):
Xin Lu;
Jung Xu
Show Abstract
Space-time coding based on transmit diversity have recently proposed as a design art of signals for transmit diversity in
satellite-data communications. The paper mainly discusses the performance of some STCs applied to the forward link of
a WCDMA multi-satellite UMTS environment. MRC, STBC, SDT and STTC have been firstly considered. Furthermore,
outer convolutional encoder have been considered to concatenate with MRC, STBC and STD, while for STTC, a
convolutional encoder plus an iterative decoding has been used to perform a STTCM. Simulation results show that STD
outperforms all the other schemes in terms of BER and FER for lower values of SNR. While the SNR is increasing,
STTC and STTCM have shown the best performances in terms of FER. Performance results with various modulation
methods for the serially concatenated convolutional STBC system are also presented here.
Robust method of reconfiguring complete broadband signal by using multi-channel and low rate sampling signal
Author(s):
Lun Ma;
Guisheng Liao
Show Abstract
It is required that an ADC for sampling broadband signal directly has high sampling rate, and this will make the
sampling accuracy decrease and difficult to be realized. This paper introduces an idea that using multi-channel and low
rate ADCs performs sampling broadband signal, then presents a novel method of utilizing adaptive beam forming
technique to recover complete bandwidth of the broadband signal. Application of this method can implement both low
rate sampling and high accuracy; in addition, it is robust to channel delay and other errors. The result of processing the
simulated data has verified the effectiveness of this method.
Real-time performance validation of spread spectrum aloha for satellite formation flying
Author(s):
Wenxun Qiu;
Xiaochun Gong;
Guodong Xu
Show Abstract
In this paper, a broadcast channel model is set up to analyze and validate the real-time performance of the spread
spectrum ALOHA used in satellite formation flying. A three-satellite formation flying system model is the concretion of
the model. In the model, a frame definition referenced CCSDS recommended standard is imported. According the three-satellite
model, this paper deducts the delay probability, the probability of collision and the mean time of communication
to estimate the performance of spread spectrum ALOHA. By simulation, it validates that spread spectrum ALOHA has a
good real-time performance in the model of satellite formation flying, which could satisfy milliseconds order
requirement in distance of several hundred kilometers.
Satellite mission scheduling algorithm based on GA
Author(s):
Baolin Sun;
Lifei Mao;
Wenxiang Wang;
Xing Xie;
Qianqing Qin
Show Abstract
The Satellite Mission Scheduling problem (SMS) involves scheduling tasks to be performed by a satellite, where new
task requests can arrive at any time, non-deterministically, and must be scheduled in real-time. This paper describes a
new Satellite Mission Scheduling problem based on Genetic Algorithm (SMSGA). In this paper, it investigates
algorithmic approaches for determining an optimal or near-optimal sequence of tasks, allocated to a satellite payload
over time, with dynamic tasking considerations. The simulation results show that the proposed approach is effective and
efficient in applications to the real problems.
A utility oriented radio resource management algorithm for heterogenous network
Author(s):
Xiaoyan Wang;
Yan Dong;
Zailu Huang
Show Abstract
A utility oriented radio resource management algorithm is proposed for broadband nongeostationary satellite network
which works in the heterogeneous network environment and provides access services for various customers on the
ground. Based on the game theory, the problem for optimizing the network's performance is turned into the problem for
maximizing the network's long term utility in the proposed algorithm. With evaluation to the traffic condition and
dimensions of Qos for the network at the moment while the access service requirements changing, the influence of this
service requirement to the long term utility of the satellite network is audited and then the resource assignment decision
can be made according to the rule for maximizing the satellite network's long term utility. The process directed by game
theory guaranteed both that the benefit of the network and the requirements of the customers could be considered
synthetically. The simulation results demonstrate the effectiveness of the proposed algorithm.
Cascade connection serial parallel hybrid acquisition synchronization method for DS-FHSS in air-ground data link
Author(s):
Feng Wang;
Desuo Zhou
Show Abstract
In air-ground tactical data link system, a kind of primary anti jamming technology adopted is direct sequence -
frequency hopping spread spectrum (DS-FHSS) technology. However, how to implement the quick synchronization of
DS-FHSS is an important technology problem, which could influence the whole communication capability of system.
Thinking of the application demand of anti jamming technology in actual, a kind of cascade connection serial parallel
hybrid acquisition synchronization method is given for the DS-FHSS system. The synchronization consists of two stages.
The synchronization of FH communication is adopted at the first stage, and the serial parallel hybrid structure is adopted
for the DS PN code synchronization at the secondary stage. Through calculating the detect probability of the FH
synchronization acquisition and the acquisition time of DS code chip synchronization, the contribution to the
synchronization capability of system by this method in this paper is analyzed. Finally, through simulating on computer,
the performance estimate about this cascade connection serial parallel hybrid acquisition synchronization method is
given.
Bluetooth-based wireless sensor networks
Author(s):
Ke You;
Rui Qiang Liu
Show Abstract
In this work a Bluetooth-based wireless sensor network is proposed. In this bluetooth-based wireless sensor networks,
information-driven star topology and energy-saved mode are used, through which a blue master node can control more
than seven slave node, the energy of each sensor node is reduced and secure management of each sensor node is
improved.
Piecewise linear control allocation for flying wing UAV
Author(s):
Peng Wang;
Zhou Zhou
Show Abstract
A piecewise linear control allocation approach was presented for the solution of the non-linear control allocation
problem for flying wing Unmanned Aerial Vehicle (UAV). The presented approach utilizes the piecewise linear
assumption for the control effector moment data. This assumption allows the non-linear control allocation problem to be
cast as a piecewise linear program. In order to solve the piecewise linear program, it was re-formulated as a mixed-integer
linear program. The discussed mixed-integer linear programs were implemented in a nonlinear Simulink
simulation of a flying wing UAV landing phase. The analysis of the simulation results showed that the piecewise linear
program approach results in improved tracking performance when compared to a more traditional control allocation
approach that uses a linear approximation of the control moments, especially when the aircraft is subjected to control
effector failures.
Neural networks filter for hybrid navigation of formation flying spacecraft in deep space
Author(s):
Hui Li;
Qinyu Zhang;
Naitong Zhang
Show Abstract
Autonomous navigation of spacecrafts is of a difficulty task, however which is a must in future deep space exploration.
With multiple spacecrafts flying in space, this aim can be achieved by formation flying spacecrafts utilizing ITDOA and
IDD methods, which can locate the position of earth-station from one-way uplink signals in the FFS coordinate, and by
way of conversion of coordinates, the position of FFS is achieved in ECEF coordinate. The ability of neural network
filter in navigation to extract position of spacecrafts from random measuring noise of signal arrival time and Doppler
shift is studied with different radius of FFS and surveying parameters. The NN filter used by spacecraft group is new
way of unidirectional autonomous navigation and is of highly precision of hybrid navigation.
UNB modulation in high speed space communications
Author(s):
Lenan Wu
Show Abstract
Radio spectra in space are close-packed more and more, so its impact of frequency as a valuable resource is increasingly
prominent. Based on reviews of those classical methods a communication engineer accustomed to, this paper will
interpret the theoretic foundation and key technology of the Ultra Narrow Band (UNB) modulation and demodulation,
and gives a system scheme for UNB transmissions. This UNB scheme includes a unitive expression for extending of
binary phase modulations, a realization of its modulator and demodulator (MODEM), and especially an important UNB
filter. Applications to space communication of the proposed high data rate UNB MODEM are discussed.
Conformance testing to space communication network
Author(s):
Lei Xie;
Jiaolong Wei;
Guangxi Zhu
Show Abstract
Space Internet technology is the Internet that refers to technology which is widely used in the terrestrial network,
improved under the space communications feature, thus using the improved Internet protocols and technology, to meet
the needs of future space mission technology. In protocol engineering area, conformance testing is a very important step.
The purpose of conformance testing is to determine to what extent a single implementation of a particular standard
conforms to the individual requirements of that standard. Conformance testing can increase the confidence level of
implementation complying with the protocol specification, and enhance the probability of interoperability between
different implementation. The ISO/IEC9646 standard described by ISO is the maturest theory in protocol conformance
testing theories. Space communication network test framework is proposed, in which the test architecture is defined for
conformance testing to space communication network. In this paper, the ISO9646 standard is improved, in order to meet
the requirements of conformance testing of space communication network. The contribution of this paper is the
proposition of a complete method to the design of conformance testing against space communication network. The
simulation results have shown that the method has better test results, to meet the space communications network testing
needs. With the testing of the space communications network protocol implementation, we discovered the problems of
the protocol implementation. It has verified the theory and method.
Pseudo-random dynamic address configuration (PRDAC) algorithm for mobile ad hoc networks
Author(s):
Shaochuan Wu;
Xuezhi Tan
Show Abstract
By analyzing all kinds of address configuration algorithms, this paper provides a new pseudo-random dynamic address
configuration (PRDAC) algorithm for mobile ad hoc networks. Based on PRDAC, the first node that initials this network
randomly chooses a nonlinear shift register that can generates an m-sequence. When another node joins this network, the
initial node will act as an IP address configuration sever to compute an IP address according to this nonlinear shift
register, and then allocates this address and tell the generator polynomial of this shift register to this new node. By this
means, when other node joins this network, any node that has obtained an IP address can act as a server to allocate
address to this new node. PRDAC can also efficiently avoid IP conflicts and deal with network partition and merge as
same as prophet address (PA) allocation and dynamic configuration and distribution protocol (DCDP). Furthermore,
PRDAC has less algorithm complexity, less computational complexity and more sufficient assumption than PA. In
addition, PRDAC radically avoids address conflicts and maximizes the utilization rate of IP addresses. Analysis and
simulation results show that PRDAC has rapid convergence, low overhead and immune from topological structures.
Advanced routing in interplanetary backbone network
Author(s):
Ge Xu;
Min Sheng;
Chengke Wu
Show Abstract
Interplanetary (IPN) Internet is a communication infrastructure providing communication services for scientific data
delivery and navigation services for the explorer spacecrafts and orbiters of the future deep space missions. The
interplanetary backbone network has the unique characteristics hence routing through the backbone network present
many challenges that are not presented in traditional networks. Some routing algorithms have been proposed, in which,
LPDB integrates the shortest path algorithm and the directional broadcast method to guarantee fast and reliable message
delivery. Through this mutipath routing strategy, unpredictable link failures is addressed, but additional network
overhead is introduced. In this paper, we propose an improvement of the LPDB named ALPDB in which the source
could adaptively decide the next-hop nodes according to the link condition, hence reduce the network overhead. We
model this algorithm on the network simulation platform of OPNET and compare it with other applicable algorithms in
data passing ratio, data delay and network overhead. The result indicates that the ALPDB algorithm could not only
guarantee reliable message delivery, but also decrease the cost significantly.
A lightweight secure routing algorithm for ad hoc networks with free-space optics
Author(s):
Zhong Xu;
Guanzhong Dai;
Guoqing Zhang;
Xue Liu;
Deming Yang
Show Abstract
Nowadays, there are some works with free-space laser communication system, but security issues of this network are
always neglected. We present an efficient online/offline routing based on identity-based signature for ad hoc networks
with Free-Space-Optics (FSO). The protocol is especially suitable for ad hoc networks with FSO because the major
computational overhead is shifted to the offline phase, whereas the online phase requires only a very low computational
overhead to achieve a full scale of authentication. In addition, since the signature scheme uses an identity-based
cryptosystem, it does not need to maintain a public key directory and to exchange any certificate. The effectiveness of
our protocol is simulated using QualNet tools.
On the approximate model of scattering radiance for cloudless sky
Author(s):
ChunPing Yang;
Jian Wu;
Yong Han;
XiuLan He;
Jie Leng
Show Abstract
Effect factors on sky radiance were analyzed based on the transfer theory of light in the random medium. In fact, these
factors mainly include: 1) absorbed and scattered extinction of solar radiance by atmosphere; 2) single scattering process
of solar radiance by atmosphere along viewing direction; 3) multiple scattering process of solar radiance by atmosphere
along viewing direction; 4) thermal radiation of atmosphere. The latter three ones among these factors increase sky
radiance. After this analysis, derivative process of the Radiative Transfer Equation was studied thoroughly from the law
of conservation of energy and the transmission of solar radiance in the earth-atmosphere system, and some methods of
dealing with the multiple scattering are analyzed and used in calculating sky radiation. Finally, an approximate model
was developed for sky radiance of sunshiny and cloudless sky to make full use of the RTE, an analytical express of sky
radiance is gave out for single scattering and quasi-multiple scattering effects. Sky spectral radiance was calculated for
some representative case of clear sky, and results have been compared with those of MODTRAN. The results show that
the present model is efficient under the sunny and cloudless condition.
Channel aware HARQ scheme based on LDPC codes for land mobile satellite communication system
Author(s):
Yongli Yang;
Guangxi Zhu;
Desheng Wang;
Lifen Wu
Show Abstract
In this paper, a channel aware HARQ (CA-HARQ) scheme based on data punctured rate compatible LDPC (DP-LDPC)
codes, which might satisfy the demand for bandwidth and rate in land mobile communication system, is proposed. The
scheme is based on type II HARQ technique cooperated with a DP- LDPC code. In the proposed scheme, the effective
rate of the LDPC code is adapted according to the channel quality information (CQI) estimated at the receiver, so as to
decrease the redundancy when the channel is good and vice versa, the retransmitted blocks are combined with the
previous information transmitted to achieve high probability of successful decoding. In this paper, we use a 2-bit CQI
feedback scheme. Simulation results, which based on a land mobile satellite channel, show that the proposed channel
aware H-ARQ scheme based on DP-LDPC codes improved the throughput by 0.4dB at low SNR compared to a pure DP-LDPC
type II HARQ, and it can also be an effective solution to compensate rain attenuation and multipath fading in land
mobile satellite systems.
Doppler shift estimation in DS/SS receiver using correlation-peak waveform fitting
Author(s):
Tingyan Yao;
Weigang Zhao;
Qishan Zhang;
Yanhong Kou
Show Abstract
We consider the estimation of Doppler shift of the data-modulated signal in the direct sequence spread spectrum (DS/SS)
communication system. A new open-loop Doppler shift estimation algorithm is developed by taking advantage of the
priori knowledge that correlation peak is Sinc-function of Doppler shift in the DS/SS receiver. The proposed algorithm
samples correlation peaks on different Doppler shifts and fits these samples to the correlation peak curve using a
nonlinear least squares method. Performance of the proposed method is demonstrated by statistical analysis and
numerical simulation. And a comparison with the four-quadrant frequency discriminator algorithm (FQFD) is given.
Feature extraction algorithm for space targets based on fractal theory
Author(s):
Balin Tian;
Jianping Yuan;
Xiaokui Yue;
Xin Ning
Show Abstract
In order to offer a potential for extending the life of satellites and reducing the launch and operating costs, satellite
servicing including conducting repairs, upgrading and refueling spacecraft on-orbit become much more frequently.
Future space operations can be more economically and reliably executed using machine vision systems, which can meet
real time and tracking reliability requirements for image tracking of space surveillance system.
Machine vision was applied to the research of relative pose for spacecrafts, the feature extraction algorithm was the basis
of relative pose. In this paper fractal geometry based edge extraction algorithm which can be used in determining and
tracking the relative pose of an observed satellite during proximity operations in machine vision system was presented.
The method gets the gray-level image distributed by fractal dimension used the Differential Box-Counting (DBC)
approach of the fractal theory to restrain the noise. After this, we detect the consecutive edge using Mathematical
Morphology.
The validity of the proposed method is examined by processing and analyzing images of space targets. The edge
extraction method not only extracts the outline of the target, but also keeps the inner details. Meanwhile, edge extraction
is only processed in moving area to reduce computation greatly. Simulation results compared edge detection using the
method which presented by us with other detection methods. The results indicate that the presented algorithm is a valid
method to solve the problems of relative pose for spacecrafts.
Study on image compression coding based on ESPIHT in the free space laser communication
Author(s):
Jingfeng Zang;
Xuhua Zhai;
Fu Sun;
Yan Piao;
Xiaoyuan Yan;
Fuchang Yin
Show Abstract
Free-space laser communication is a research direction in wireless communication domain. The image transmission,
compression coding and storage are ones of most important techniques in the free space laser communication. In order to
improve error resilient capability and transmission efficiency for image transmission over noisy and varying channels in
the free space laser communication (FLSC) , we contrive a joint source and channel coding (JSCC) scheme, in which
extended set partitioning in hierarchical trees (ESPIHT) and rate compatible punctured convolutional code (RCPC) are
used. Specifically, ESPIHT segments an image into different sizes of blocks whilst determining different levels of source
significance; RCPC code is then used to provide unequal error protection for individual blocks. Various simulations
show that this scheme can support robust and efficient image transmission in a very effective way.
Experiments demonstrate that the proposed method can obviously improve the image quality compared to that of the
classical approach of separate source and channel coding. The peak SNR for reconstruction image also has some
improvement. It is an effective fast image compression method.
Application of IP multicast of network speech in satellite TT&C ground station
Author(s):
Tao Zhang;
Li Zhou;
Yongsheng Gui;
Weitao Tie
Show Abstract
After analyzing the existing problems in real-time mission scheduling of satellite TT&C ground station, the live
communication function of real-time scheduling speech fit for mission scheduling system in ground station is developed, using the IP multicast technology and multimedia speech processing technology, then the reliability of multicast is
improved, and a network simulation test is made.
Modeling ad hoc network based on 802.11 DCF by queuing network analyzer
Author(s):
Wenbin Zhang;
Zhongzhao Zhang
Show Abstract
In this paper, we present an analytic model for evaluating the average end-to-end delay and per-node throughput in an
IEEE802.11MAC DCF based wireless network. By virtue of QNA and probability generation function, we model ad hoc
network as open M/G/1 queuing networks and obtain the closed form expressions for average end-to-end delay.
Simulations based on NS2 validate the accuracy of our model.
Design of on-board Bluetooth wireless network system based on fault-tolerant technology
Author(s):
Zheng You;
Xiangqi Zhang;
Shijie Yu;
Hexiang Tian
Show Abstract
In this paper, the Bluetooth wireless data transmission technology is applied in on-board computer system, to realize
wireless data transmission between peripherals of the micro-satellite integrating electronic system, and in view of the
high demand of reliability of a micro-satellite, a design of Bluetooth wireless network based on fault-tolerant technology
is introduced. The reliability of two fault-tolerant systems is estimated firstly using Markov model, then the structural
design of this fault-tolerant system is introduced; several protocols are established to make the system operate correctly,
some related problems are listed and analyzed, with emphasis on Fault Auto-diagnosis System, Active-standby switch
design and Data-Integrity process.
Nonlinear geometric feature equalizers based on minimum bit error rate criterion for EBPSK communications
Author(s):
Renxiang Zhu;
Lenan Wu
Show Abstract
A novel nonlinear geometric feature equalizer based on minimum bit error rate is proposed in this paper for the filtering
of noise and interference whose frequency band overlaps with the desired signal in extended binary phase shifting keying
communications. Considering that the desired signal and the interference have different stochastic characters in feature
space, the proposed equalization algorithm recovers the desired signal by neural network. Simulation results show that
when extended binary phase shifting keying signals are contaminated by relatively strong interference, geometric feature
equalizers can provide very low bit error rate. This will provide an alternate filter used for extended binary phase shifting
keying communications and also for deep-space communications etc.
Resource planning and scheduling of payload for satellite with particle swarm optimization
Author(s):
Jian Li;
Cheng Wang
Show Abstract
The resource planning and scheduling technology of payload is a key technology to realize an automated control for
earth observing satellite with limited resources on satellite, which is implemented to arrange the works states of various
payloads to carry out missions by optimizing the scheme of the resources. The scheduling task is a difficult constraint
optimization problem with various and mutative requests and constraints. Based on the analysis of the satellite's
functions and the payload's resource constraints, a proactive planning and scheduling strategy based on the availability
of consumable and replenishable resources in time-order is introduced along with dividing the planning and scheduling
period to several pieces. A particle swarm optimization algorithm is proposed to address the problem with an adaptive
mutation operator selection, where the swarm is divided into groups with different probabilities to employ various
mutation operators viz., differential evolution, Gaussian and random mutation operators. The probabilities are adjusted
adaptively by comparing the effectiveness of the groups to select a proper operator. The simulation results have shown
the feasibility and effectiveness of the method.
An integrated image fusion method based on multi-resolution analysis and directional gradient
Author(s):
Shichun Peng;
Ying Huang
Show Abstract
The images obtained by different sensors differ from each other in terms of resolution and spectrum. Image fusion is a
very useful technique which focuses on forming a new image by combining the unique and complementary information
provided by different images. A new image fusion method based on multi-resolution analysis and directional gradient is
described in this paper. The key idea is to use different fusion strategies along different directions, in order to take into
account the anisotropy of the images. The directional gradient is used in describing directional property. Experimental
results show that the proposed method is effective and promising to enhance visualization in the fused image.
Path loss characteristics for UWB signal long-distance transmission
Author(s):
Yang Wang;
Qinyu Zhang;
Naitong Zhang;
Jie Zhang
Show Abstract
Impulse systems do not undergo the multipath destructive interference that manifests itself as Rayleigh fading prevalent
in continuous wave systems, but rather show up as delayed replicants of the direct impulse. In this paper, the path loss
characteristics for impulse signals propagation over a plane earth are proposed. The condition for direct pulse and its
replicant overlapping with each other is investigated. The polarization of the transmission signals, which was always
neglected by previous approaches, is taken into account here. Moreover, a new time domain reflection coefficient, which
is simple and accurate in comparing with conventional results, is adopted in developing the reflected pulsed field. The
simulation result shows that the path loss can be characterized as 3 zones with different path loss exponent as distance
between transmitter and receiver (T-R) increasing.
Ricker wavelet LS-SVM and its parameters setting for seismic prospecting signals denoising
Author(s):
Xiaoying Deng;
Yue Li;
Baojun Yang
Show Abstract
LS-SVM (Least Squares-Support Vector Machines) are applied to seismic prospecting signals denoising so as to
suppress the stochastic noise in this paper. Firstly, we propose and prove a new admissible support vector kernel-Ricker wavelet kernel, which is superior to the popular RBF (radial basis function) kernel in terms of the waveform
retrieved and SNR (Signal to Noise Ratio) gained when applied to the noise reduction of seismic prospecting signals.
LS-SVM embed two tuning parameters which may diminish the overall performance of LS-SVM if not well chosen, so
we investigate the selection of LS-SVM parameters including kernel parameter and regularization parameter,
respectively. We can conclude that Ricker wavelet kernel parameter should be set as the predominant frequency of
seismic signal and regularization parameter γ can be accepted in a wide range. Our denoising experimental results show
that the performance of Ricker wavelet LS-SVM using the aforementioned parameters setting outperforms Wiener
filtering, median filtering and LS-SVM based on RBF kernel in terms of the definition of seismic prospecting event
retrieved and SNR gained.
Research on power-law acoustic transient signal detection based on wavelet transform
Author(s):
Jian-hui Han;
Ri-jie Yang;
Wei Wang
Show Abstract
Aiming at the characteristics of acoustic transient signal emitted from antisubmarine weapon which is being dropped into
water (torpedo, aerial sonobuoy and rocket assisted depth charge etc.), such as short duration, low SNR, abruptness and
instability, based on traditional power-law detector, a new method to detect acoustic transient signal is proposed. Firstly
wavelet transform is used to de-noise signal, removes random spectrum components and improves SNR. Then Power-
Law detector is adopted to detect transient signal. The simulation results show the method can effectively extract envelop
characteristic of transient signal on the condition of low SNR. The performance of WT-Power-Law markedly outgoes
that of traditional Power-Law detection method.
Feedback-based multipath routing for mobile ad hoc networks
Author(s):
Yuanhui Ning;
Guangxi Zhu;
Gang Su;
Li Tan
Show Abstract
A mobile ad hoc network is characterized by multi-hop wireless links, absence of a fixed infrastructure, and frequent
host mobility. The instability of the topology in this type of networks makes multipath routing difficult for the available
alternative paths are inherently unreliable. So far, much of the effort of multipath routing has been focused on using the
predefined alternate path when a relay on the primary path has failed despite the alternate path is out of use. Accordingly,
this reactive route handoff can decrease the overall network performance with increasing routing overhead. In this paper,
we propose a feedback-based multiple paths route scheme and provide its analytical evaluation. Our scheme is based on
utilizing an alternative path as a feedback channel to carry path state information for primary path. In this regard, it can
proactively give up the primary path and use the current candidate path as primary path before it breaks. In this paper, we
consider the problem of routing data over multiple disjoint paths via an analytic modeling framework to determine the
frequency of routing discovery procedure. The results show that a significantly better performance than the single path
routing and traditional multipath routing can be achieved.
Analysis of coupled-cavity slow-wave structures for space TWT
Author(s):
Zelun Li;
Guoqiang Lv;
Shanxi Deng;
Youjun Huang;
Jun Yang;
Guangsheng Deng
Show Abstract
Cold-test characteristics including dispersion and coupling impedance of a coupled-cavity slow-wave structure for space
TWT working in millimeter band have been simulated by self-designed software. The slow-wave structure has been
modeled and cold-test characteristics data were obtained. The interaction between electromagnetic wave and electron
beam has also been analyzed qualitatively. The study in the paper can provide some references for the design of coupled-cavity
slow-wave structure for space TWT.
The programming realization of image compression algorithm in satellite data compression equipment
Author(s):
Jidong Wang;
Wusheng Luo;
Qin Lu;
Xuemin Xiao
Show Abstract
Satellite remote sensing image compression system is expected high compressing rate, real time dealing and high
fidelity. Based on lapped biorthogonal transform (LBT) and its integer algorithm, this paper describes a fixed-point
lapped transform algorithm using approximation to trigonometric function, studies the structure of LBT coefficients and
presents a modified zerotree coding algorithm. Also, this paper studies the implementation in TMS320C6000 DSP of the
algorithm, the processing speed is improved through task combining, complier options, software pipelining, loop
unrolling and complex instruction. This algorithm has been used in a prototype of data compression equipment. Image
coding experiments show that the algorithm's memory requirement is low and its coding performance is very
competitive with SPIHT when its complexity is far lower than SHIHT.
A measurement study of peer-to-peer applications
Author(s):
Bin Liu;
Zhitang Li;
Hao Tu
Show Abstract
P2P applications for file-sharing and video streaming have become tremendously popular in recent years, and it is now
accounting for a significant share of the total network traffic. As P2P applications nowadays tend to use arbitrary ports to
camouflage their communications, traditional methods like port-based identification have become highly inaccurate. In
this paper, we propose a measurement system to detect and measure the real-time P2P traffic more reliably. The
measurement methodology is based on using application level signatures implemented by netfilter extension as well as
packet classifier. We further present the results from a P2P traffic analysis at a campus network, which show that this
P2P traffic measurement system can provide the performance and scalability required for practical applications.
A background rejection method based on star-point matching in star-background image
Author(s):
Zunyan Liu;
Danpei Zhao;
Zhiguo Jiang
Show Abstract
This paper addresses the problem of rejecting fixed star background in star-background image. For most sensors with a
fine spatial resolution, phenomenological effects, such as background, and system effects, such as noise, contribute
significant numbers of spurious points to each frame. In star-background images, fixed stars are uppermost source of
spurious points. Since background and noise do not behave like targets, a good tracking algorithm would eventually
reject the spurious points as non-targets. However, the computation required to consider which points appearing in a
frame are from the target grows geometrically with the number of points to be considered. Simply considering each of
these points as a candidate target point unnecessarily burdens the tracking algorithm and in many cases would require
computational resources that cannot be provided to the mission. In this paper, we proposed a new method for rejecting
fixed stars based on star-point matching in star-background image. We decide the fixed stars using point matching
between points in actual image and points in ideal image which relies on the catalog. This work extends applied domain
of Hausdorff Distance (HD) which is one of commonly used measures for object matching. In our experiments, Least
Trimmed Square HD (LTS-HD) was used in point matching, and the result is effective.
Visualization of large scale geologically related data in virtual 3D scenes with OpenGL
Author(s):
Dewen Seng;
Xi Liang;
Hongxia Wang;
Guoying Yue
Show Abstract
This paper demonstrates a method for three-dimensional (3D) reconstruction and visualization of large scale
multidimensional surficial, geological and mine planning data with the programmable visualization environment
OpenGL. A simulation system developed by the authors is presented for importing, filtering and visualizing of
multidimensional geologically related data. The approach for the visual simulation of complicated mining engineering
environment implemented in the system is described in detail. Aspects like presentations of multidimensional data with
spatial dependence, navigation in the surficial and geological frame of reference and in time, interaction techniques are
presented. The system supports real 3D landscape representations. Furthermore, the system provides many visualization
methods for rendering multidimensional data within virtual 3D scenes and combines them with several navigation
techniques. Real data derived from an iron mine in Wuhan City of China demonstrates the effectiveness and efficiency
of the system. A case study with the results and benefits achieved by using real 3D representations and navigations of the
system is given.
Methods of RVD object pose estimation and experiments
Author(s):
Yang Shang;
Yan He;
Weihua Wang;
Qifeng Yu
Show Abstract
Methods of measuring a RVD (rendezvous and docking) cooperative object's pose from monocular and binocular
images respectively are presented. The methods solve the initial values first and optimize the object pose parameters by
bundle adjustment. In the disturbance-rejecting binocular method, chosen measurement system parameters of one
camera's exterior parameters are modified simultaneously. The methods need three or more cooperative target points to
measure the object's pose accurately. Experimental data show that the methods converge quickly and stably, provide
accurate results and do not need accurate initial values. Even when the chosen measurement system parameters are
subjected to some amount of disturbance, the binocular method manages to provide fairly accurate results.
The design of highly reliable on-board data handling software for micro-satellite
Author(s):
Ping Wang
Show Abstract
The thesis introduces the on-board computer (OBC) software of Chuangxin-1 micro-satellite which developed by
shanghai micro-satellite engineering department of Chinese Academy of Science, and illustrates the reliable design for
on-board data handling (OBDH) software. The OBDH software adopted some new techniques to improve the reliability.
The micro-satellite employed dual-computer, and the standby OBC will take over the management of micro-satellite as
soon as the host is failure. The OBC is the core of micro-satellite, and all sub-system of satellite and payload are
managed by OBC. To ensure the reliability of OBC, there are some special methods for OBDH software. For standby
OBC can take over control of micro-satellite smoothly and resume normal running when the host is failure, some
important on-orbit running information of satellite is transferred to standby OBC. These measurements assured the
micro-satellite can be resumed to normal running.
Feature extraction of attributed scattering centers on high resolution SAR imagery
Author(s):
Jin Yang;
Dong-mei Yan;
Chao Wang;
Hong Zhang
Show Abstract
The attributed scattering center model is based on the solutions from both physical optics and the geometric theory of
diffraction. In this paper, the attributed scattering center model and the method of extracting the feature of attributed
scattering centers from high resolution SAR image are discussed. The method includes four steps: image segmentation,
the selection of the model type, the estimate of initial value and the parameter optimization. Seven parameters of one
scattering center can be obtained through the above four steps. Then we can get the parameters of all the scattering
centers in the imagery by the recurrence procession. The validity of this method can be proved by the results of
simulation.
Scannerless range imaging laser radar for on-orbit surveillance of space objects
Author(s):
Wenjin Yang;
Xiaoping Du;
Jiguang Zhao
Show Abstract
The purpose of this paper is to introduce the application of scannerless range imaging (SRI) laser radar in the dynamic
and real-time surveillance for cooperative and uncooperative space objects. Scannerless range imaging technique enables
the capture of a full scene 3D range image in one acquisition with faster image acquisition speed. Small size, lighter
weight, reduced mechanically complex and faster acquisition speed make it more fit for space borne scenario. Laser
radar is based on frequency-modulated (FM) ranging principle that belongs to the time-of-flight (TOF) measurement
category. In this case, the time-of-flight is converted to a beat frequency proportional to the range to be measured. This
conversion is realized with intensity modulation of the laser power by a linear FM continuous wave. A summary of FM
ranging theory and its application in range imaging are introduced. The system architecture and theory of operation are
described. The key technologies of this type of scannerless range imaging laser radar in the application of surveillance
for space objects are discussed.
A study of carrier phase recovery and tracking for high dynamic GPS signal
Author(s):
Yan Yang;
Zhangdui Zhong
Show Abstract
This paper presents a technology to deals with the tracking performance of a timing recovery loop for dynamic
circumstance GPS receiver. Based on Lagrange interpolation theory authors propose a data interpolation control method
suitable for software radio. In our scheme, traditional code fast acquisition algorithm was employed to estimate timing
error which has high estimate accuracy. The timing correction is performed by the interpolating filter, which is derived
from the timing error detector. The carrier phase tracking can be adjusted precisely by selecting interpolating filter orders
such as linear or non-linear. The simulation shows that the timing error recovery has high tracking precision, fast
acquisition and keep track performance under high dynamic circumstance.
Research of signal tracking technology in FSO communication
Author(s):
Kai Peng;
Tianping Deng;
Yimin Lu;
Gang Lu
Show Abstract
In the decade of information, with the increment of the data rate and capacity in communication, free space optical
communication (FSO) has been paid much attention by many countries since it integrates the advantages of fiber
communication and other traditional wireless communication technologies, such as large capacity, low cost, convenient
deployment and flexibility. This paper concerns with the research on the signal tracking technology of FSO. Considering
that suppressing vibration is a difficulty of FSO, so suppressing methods are discussed in the paper. As a base, the ATP
(Acquisition, Tracking, Pointing) technology of FSO communication system is analyzed in this paper. And a new signal
tracking system for FSO communication is described. The main structure, integral parts and detailed work process of this
signal tracking system are introduced in detail.
A real-time publication system of massive marine remote sensing data
Author(s):
Jie Huang;
Renyi Liu;
Nan Liu;
Changfeng Jing;
Na Wang
Show Abstract
At present, owing to the advanced remote sensing technology, a great lot of marine raster data has been acquired. With
the marine data's keep-rising, it turns out more and more necessary to be organized, managed and displayed data
effectively so as to serve people's daily life and production. The current methods are difficult to storage and management
of the massive data efficient. And there are lots of problems with the raster data publication on the network because of its
features such as massiveness, real-time and variety. In this paper, after analyzing the related technologies of raster spatial
database engine, WebGIS and J2EE, a three-tier-structured real-time publication system of massive marine remote
sensing data is put forward. This system has been made available to users to browse, query, analyze, download, and
manage of marine remote sensing data efficiently. It was used throughout the marine water quality real-time inspecting
project on Zhejiang Province of China.
Simulation of precise orbit determination of COSMIC from onboard GPS zero-difference phase data with kinematic method
Author(s):
Jinyun Guo;
Cheinway Hwang;
Zipang Tseng;
Xiaotao Chang
Show Abstract
COSMIC is a constellation mission to study the climate, ionosphere and geodesy. The main geodetic mission of
COSMIC is to determine the global gravity field model and its temporal variations, which need the precise geometric
orbit of COSMIC. GPS observations onboard COSMIC are simulated using the GPS precise final orbit and high-rate
clock of CODE, the designed orbit of COSMIC and the GPS antennae for precise orbit determination (POD). The precise
geometric orbits of COSMIC are determined with the kinematic method from the space-borne simulated observations to
test the POD capability of GPS antennae. There are two POD GPS antennae onboard COSMIC, named as POD +X and
-X. The orbit from POD -X antenna has the approximately same precision as that from POD +X antenna, and the errors
of both are greater than the given random error while simulating GPS data. The main reason is that the designed
positions of POD antennae are not good. There are the different angels between the boresight vector and zenith direction
of two antennae. Another reason is that POD +X antenna is in the flying direction and POD -X antenna is in the inverse
direction. In order to get the high precision of POD, a virtual antenna is constructed from POD +X and -X, whose center
is the center of mass of COSMIC. Observations from POD +X and -X then are reduced to the virtual antenna.
Comparing with the referenced orbit and the kinematic orbit from the virtual antenna, the precision of orbit is consistent
to the given random error when simulating GPS data, up to centimeter level.
A digital mileage calculating program for electronic toll collection by using vehicle positioning system
Author(s):
Chi-Chung Tao;
Ching-Jung Tsai
Show Abstract
One of the fairest mechanisms of Electronic Toll Collection (ETC) would be distance-based charging, where vehicles
would pay fees at a pre-specified rate per kilometer throughout the trip. The vehicle positioning system (VPS) based on
GPS (Global Positioning System) has become the main ETC technology worldwide recently. One of the key algorithms
for VPS is how to provide accurate distance calculation data. Therefore, a digital mileage calculating program utilizing
the position information from a commercial GPS receiver to filter out noises should be developed to accumulate the total
distance of a voyage incrementally. Due to environmental climates and built-up in a metropolitan area such as high
buildings, bridges, radio stations, tunnels and traffic subways, signals of GPS satellites are easily susceptible to noises
or even totally blocked. In such cases, the GPS position information loses fidelity. This paper presents a procedural
program, incorporating an algorithmic software filter adaptive to different situations, is an answer to the above problems
and is capable of providing the mileage of a voyage in real-time base with high accuracy compared to a mechanic
mileage meter.
A single-channel SAR-GMTI algorithm based on sub-apertures and FrFT
Author(s):
Shujun Liu;
Yunneng Yuan;
Jun Wei;
Shiyi Mao
Show Abstract
This paper investigates sub-image cancellation for ground moving target indication (GMTI) with a single-antenna
airborne synthetic aperture radar (SAR). First the paper points out how to choose the sub-image from the whole image.
After the generation of the sub-image, the imaging difference of stationary object and moving object in the sub-image
based on the frequency division is analyzed. Once the detection is completed, the moving target is still dispersed and the
FrFT(Fractional Fourier Transformation) algorithm is chosen to focus it. Using FrFT algorithm, the doppler modulation
rate can be obtained so that the azimuth velocity of the moving target is estimated in this way. The theoretical analysis
and simulation results demonstrate that the method is effective and can not only detect the moving targets but also
estimate their motion parameters precisely.
Area information confrontation system based on NSV
Author(s):
Gang Wang;
Jing He;
Weimin Li;
Jiuyi Wang;
Song Li
Show Abstract
The function of Near Space Vehicle (NSV) in aerospace information system is analyzed in this paper firstly. Then the
architecture of area information confrontation system based on NSV is presented aiming at achieving superiority in area
information confrontation and the possible information confrontation mode is discussed. Finally the design of NSV
information confrontation simulation system is put forward. This paper is of guiding significance for the effective utilize
of near space as well as the development of NSV and its payload.
D-InSAR to inspect the active fault of Kunlun Mountains on Qinghai-Tibet Plateau
Author(s):
Fang Miao;
Chengming Ye;
Xiaojia Bi;
Zhenhan Wu;
Xiangsheng Kong;
Rui Liu;
Mingxing Yan
Show Abstract
Differential Interferometric Synthetic Aperture Radar (D-InSAR) is a new technology which is capable of detecting the
tiny ground deformation and extracting Digital Elevation Model (DEM). This paper introduces the basic principle of
D-InSAR. Using of two pass model and SRTM DEM, acquired Kunlun Mountains region surface deformation of Ms8.1
in 2001. The result provides an important reference for Qinghai-Tibet Railway Disaster Prevention.
Expanding the usage of the star sensor in spacecraft
Author(s):
Hua Zhang;
Hongshi Sang;
Xubang Shen
Show Abstract
Star sensors and computer vision systems are generally used for spacecraft navigation in deep space, both of which make
use of image sensors. To mitigate the payload of the spacecraft, a new star sensor prototype with extending use as a
rendezvous and docking positioning system is described in this paper. An adaptive processing element is used to control
the process of image acquiring, image pre-processing and image recognition, which makes the sharing of the image
sensor feasible. The software is discussed about how to realize the two applications. The earth based experiments verify
the feasibility and validity of the design, which may make a little contribution on the deep space explorations.
Modular simulation architecture of spaceborne/airborne hybrid bi-static SAR
Author(s):
Peng Zhou;
Yiming Pi
Show Abstract
In recent years, spaceborne/airborne hybrid bi-static synthetic aperture radar (SA-BSAR) has been proposed as a new
kind of microwave remote sensor. The SA-BSAR system combines the invulnerability of the spaceborne SAR with high
resolution and flexibility of the airborne SAR. To decrease the cost for developing a new system, a suitable flexible and
powerful simulation tool is essential. Nevertheless, the currently available SAR simulators, which were developed for
other SAR constellation, are not sufficient for SA-BSAR. This paper presents a new simulation architecture. To improve
the flexibility and the suitability of the architecture, both the requirement of SA-BSAR and the requirements of other
kinds of bi- and multi-static SAR are all fulfilled in designing the architecture. Modular configuration is the key for the
flexibility. The requirements, the framework and the steps in performing the simulator are discussed in detail.
Bistatic spaceborne SAR data processing based on LBF
Author(s):
Xia Bai;
Jinping Sun;
Fei Gao
Show Abstract
Bistatic configuration is an attractive concept for synthetic aperture radar (SAR) missions, which benefit from use of
separated transmitter and receiver flying on different platforms. The processing of radar data stands out as a fundamental
issue to facilitate bistatic SAR research and application in remote sensing. A bistatic processing algorithm based on
Loffeld's bistatic formula (LBF) is proposed. The approach involved bistatic term compensation and quasi monostatic
processing, and the latter part derived from a chirp z transform algorithm for monostatic case. As steps to a bistatic SAR
processor for space configuration, this paper presents an approximation of transmitter/receiver slat range depending on
individual incidence angle, and modifies range CZT parameter and azimuth compression operator. First results of this
algorithm on simulated raw data are included.
Modeling and predicting the extents of moving spatial objects
Author(s):
Haoran Chen;
Peiquan Jin;
Lihua Yue
Show Abstract
Recently many applications like fire simulation and tsunami monitoring bring more interests in the extents of moving
objects. Present research usually focuses on the positions of moving objects. As a result, tracking the continuously
changing extents of spatial objects is becoming increasingly necessary. This paper proposes a novel model to represent
the irregular shape of moving objects that may have parts and support the querying of the predicated near future extents.
The method is capable of representing objects evolving in one-, two- and three-dimensional space. We also provide user-defined
precision level to decide the quality of modeling. Our experimental results performed on stimulation dataset show that
the model is effective for representing and querying the extents of moving spatial objects.
A simplified method for electromagnetic scattering from periodic surface of lossy media
Author(s):
Ping Chen;
Xing Cai;
Jianxin Han;
Tianlin Dong
Show Abstract
A simplified method is presented for the problem of electromagnetic scattering of a time-harmonic plane wave from a
non-planar sinusoidal periodic surface of lossy media. Assume that the heights of the rough surface are much smaller
than the wavelength of the incidence and the space periodic of rough surface. The diffraction of the incidence can be
described by using the elementary Huygens principle. The reflected and the transmitted field approximated by a linear
combination of plane waves having different wave vectors. Based the method, we can deduce the simple formulation of
the reflected field at far suitable for engineering application.
Geospatial data and services semantic share based on ebXML registry
Author(s):
Xu Chen;
Xinyan Zhu;
Xia Zhang;
Daosheng Du
Show Abstract
Nowadays, huge volumes of geospatial data and services are available and accessible to people all over the world.
However, they are searched mostly based on keyword, which is inherently restricted by the ambiguities of natural
language, which can lead to low precision and recall. In this paper, semantic share of geospatial data and services are
studied based on ebXML registry. But ebXML registry specification doesn't take into account the registration of the
semantic information. So we define how OWL DL constructs are mapped to ebXML registry information model
(ebRIM) constructs without causing any changes in the core ebXML registry specification. After that, predefined stored
procedures are provided in the ebXML registry for semantic search, which provide necessary means to exploit the
enhanced semantics stored in the Registry. Then, geospatial ontologies in change detection application of remote sensing
based on Global Change Master Directory, ISO19119 and ISO19115 are established. Finally, a prototype system is
developed based on an open source-ebxmlrr to demonstrate the proposed model and approach.
Study on image motion compensation technology for Chinese geostationary meterological satellite remote sensing
Author(s):
Yinchao Chen;
Zhigang Wang
Show Abstract
The new generation Chinese Geostationary Meteorological Satellite (CGMS) adopts three-axis stabilized attitude control
mode, using many payloads, such as spaceborne imaging radiometer and atmospheric vertical sounder, etc, implements
all weather and real-time observation to the atmospheric environment of the Earth. The deviation of the orbit results in
the optical axis of the payloads to deviate its normal direction and then the image quality becomes lower. To acquire high
quality image, an algorithm of image motion compensation (IMC) is designed. Simulation results demonstrate that the
proposed algorithm can effectively compensate the deviation of the optical axis from the motion of the satellite orbit.
Automatic digital modulation recognition of satellite signals
Author(s):
Yingying Chen;
Yanjun Zhang;
Xin Jia
Show Abstract
This paper presents a digital modulation recognition algorithm for classifying digital signals. The algorithm is based on
high order cumulants, signal square spectrum and spectrum envelope. The advantages of this methods lies on no need for
prior knowledge of the signal. We can even estimate its code rate and SNR. Simulation results demonstrate the efficiency
of this method.
A new algorithm of gravity matching aided navigation
Author(s):
Li Yan;
Chenfeng Cui
Show Abstract
Up to now, TERCOM hasn't been used in the gravity matching aided navigation, because of its disability in precise
positioning. So does ICCP, which needs precise initial values, whereas the initial values provided by INS are not
accurate enough. This paper starts from the introduction of the basic principles of TERCOM and ICCP, and compares
their advantages and disadvantages, then incorporates these two methods into a new algorithm in which TERCOM
provides the initial position and ICCP does the precise positioning. At last simulation data is used in the experiments,
with the purpose to shed light on the effect of this new algorithm in gravity matching aided navigation. It is proved that
the new method is precise and needs no initial values. It is very fit for gravity matching aided navigation.
Organization and management of mass remotely sensed data for content-based retrieval
Author(s):
Qimin Cheng;
Guangxi Zhu
Show Abstract
Nowadays increasing attention has been paid to reasonable organization and effective management of vast amounts of
remotely sensed data for the goal of quick browse, convenient query and Retrieval-on-Demand service.
In this paper, in order to reach compromise among precision, efficiency and storage and to realize ROI coding, data
partition based on Nona-tree data structure and data compression based on JPEG2000 are adopted to organize and
manage original remotely sensed images. Afterwards, a prototype system in three-tier B/S mode is developed to test the
validity of our data organization and management strategy for content-based retrieval mentioned above. In this system,
texture-based and shape-based feature extraction algorithms based on wavelet transformation, math morphology and
other relative theory are applied. Corresponding feature descriptor and similarity calculation are also given. At last,
experimental results are given to show that the strategy proposed in this paper is valid, followed by brief conclusions and
future directions. The work of this paper is useful to push the development of geo-spatial information services and
promote content-based retrieval of remotely sensed images from experimentation to practicality.
Study on spacecraft motion compensation technology for Chinese geostationary meteorological satellite remote sensing image
Author(s):
Yankai Cui;
Zhigang Wang
Show Abstract
Because the satellite comes under influences from all kinds of disturbance and some of them can not be absorbed by
flywheel control system during the circulation, attitude of satellite is disturbed, which results in pixel excursion of the
scan mirror image, and image quality is affected. It is necessary to be compensated. Spacecraft motion compensation
means that the influences of attitude disturbance are eliminated through producing scan mirror motion control
compensation signal according to compensation arithmetic. It can be realized by using real-time compensation method
and model predictor method. This paper studies real-time spacecraft motion compensation method. The valid arithmetic
of spacecraft motion compensation and practicable technology project are proved through simulation. The research
provides theoretical principles and practicable references to develop the new generation Chinese geostationary
meteorological satellite.
A methodology for fusion LIDAR and digital images
Author(s):
Fei Deng;
Shuiming Li;
Guozhong Su
Show Abstract
This paper describes an algorithm framework for fusion airborne based laser scanning data (LIDAR) and optical images.
A efficient and reliable intensity-based registration framework has been used to determining the spatial transform form
LIDAR to optical images. On the basis of segmented airborne images, the paper raises the arithmetic and process of
merging multi-data sources to carry through classification by using multi-echo, point's space discrete characteristics, and
the statistic spectrum characteristics. In addition to the theoretical method, the paper presents a experimental analysis the
sensitivity and robustness of this approach to assess effectiveness the proposed arithmetic.
An adaptive algorithm of relative radiometric normalization based on feature corner
Author(s):
Xiaolian Deng;
Changyao Wang;
Mingguo Wei
Show Abstract
An adaptive algorithm of relative radiometric normalization for multi-temporal remote sensing images based on feature
corner was introduced in this paper. The main purpose of this research was to explore an automatic and robust algorithm
of relative radiometric normalization to minimize imaging differences of multi-temporal satellite images. The main idea
was to construct statistical regression model of relative radiometric normalization by extracting steady ground point
correspondences. The algorithm's detailed processes were as follows: First, a method of image matching was applied to
recognize steady ground point correspondences of multi-temporal remote sensing images. Second, a statistical regression
model of relative radiometric normalization was constructed to calibrate imaging difference of multi-temporal remote
sensing images. By the experiments, we could see that the total RSME of reference image and corrected image was
reduced apparently in comparison with the total RSME of reference image and uncalibrated image, and the hue of
corrected image was looked more like that of reference image. We could conclude that this modified algorithm was more
accurate and efficient than traditional algorithm, its adaptive characteristic made it easy to be integrated, and it had more
feasibility and applicable value.
Research on the method of sensor grid modeling based on graph theory
Author(s):
Yong Deng;
Xiaohui Hu;
Zhongzhao Zhang
Show Abstract
This paper discusses the problem of modeling sensor grid (SG). Firstly, the SG's structure is analyzed, and the
interconnection and interoperation relationships of sensors are described. Secondly, the definition of SG's directed graph
is presented and a SG's modeling method based on graph theory is proposed. Finally, as an example, the STSS system is
analyzed based on directed graph model.
A new GMTI detector based on spaceborne single channel SAR
Author(s):
Fei Gao;
Jinping Sun;
Xia Bai;
Zhenming Yu
Show Abstract
This paper examines moving targets detection using single channel Synthetic aperture radar (SAR) in spaceborne
platform. Building on previous work moving targets can be retrieved from multi-look images via magnitude subtraction
or phase interferometry. A more effective method is proposed which mainly consists of signal subspace processing-
based data equilibrium and change detection in multi-look covariance matrix. Also different baseline is checked and
weak targets may be found. Test results show that precise calibration of multi-look images are essential and short
baseline is preferred when the interesting targets are weak. Therefore, the proposed method leads to improved detection
performance and provides ways of GMTI in single channel SAR.
Characters and development of laser ranging technology on small-satellite relative position measurement
Author(s):
Peng Gao;
Zheng You
Show Abstract
Now, more and more technology innovation and evolution have been used on the small satellite for remote measurement,
target searching and tracking missions being performed in space. To achieve the formation flying relative navigation, and
the formation flying relative control intelligently, or to implement some important missions, the inter-satellite relative
position must be known. In this paper, the measurement procedures of small satellite relative position are given. To get
precise result of inter-satellite relative position under general conditions and some specific conditions, laser ranging
method is one of the most valuable methods which should be considered. Although the laser ranging method is well
known, its application on small satellites in space is challenge to the typical conception. Through discussion of the
principles of laser ranging and characters in different conditions, the relations of the measurement reliability, the
measurement precision and the measurement condition are presented. The difference of the measurement in space and
that in general condition is mentioned. Because of the laser ranging specific characters in small satellites
formation-flying, some conclusion of laser ranging method will not be suitable for usage in space. The details of the
causation are discussed. The use of near frequencies scale to resolve distance measurement, which is widely used in
most project applications, is the major causation of that some conclusion of laser ranging method will not be suitable for
usage in space. And use of separate frequencies scale to resolve distance measurement in space still has its own
restriction. Then the modified laser ranging method using code modulation is designed. The parts of this method and the
solve arithmetic are presented. While, this laser ranging method may require help of other means to achieve the
continuous measurement of relative position in some specific missions. Finally, the outlook of the inter-satellite relative
position measurement technologies and the applications of inter-satellite relative position measurement are represented.
2D torus inter-chip network on EOPCB for locally intensive communication
Author(s):
Yonghua Feng;
Fengguang Luo;
Jing Yuan
Show Abstract
A star-based two-dimensional (2-D) torus inter-chip network on electro-optical printed circuit board (EOPCB) is
proposed to provide a simple and effective interconnection solution for such a real-time distributed parallel systems as
satellite image processing, which is characterized with locally intensive communication. The proposed hybrid
interconnection network has a hierarchical structure where the higher level is a 2-D torus network of 8×8 optical cross-connects
(OXCs) and the lower level is a cluster of processors connected in star topology using4×4OXCs. EOPCB is
used to eliminate the electrical bottleneck of high speed interconnection on board. OXCs are used to eliminate the
expensive E/O/E conversion of electrical routers and provide a transparent optical channel between processors. A new
approach based on combination network is proposed to construct 4×4 and 8×8OXCs with 2×2optical crossbars.
Method for moving point target detection in image sequences based on directional cumulation
Author(s):
Shan Gao;
Penglang Shui
Show Abstract
A new algorithm based on directional cumulation is presented to detect the trajectory of moving point target from image
sequences in low SNR environments. First, single frame detection is performed, and then the logical "or" operation of
multiple frames are used to obtain a binary planar projective image. With that based on the continuity of the moving
trajectory of the point target, the second detection using directional cumulation is performed to acquire the trajectory of
the target and its parameters. The result of experiments shows that the proposed method is effective to detect and track
targets moving along linear or curvilinear trajectory with unrestricted velocity in low SNR, and it is of low complexity.
Study on landmark-based qualitative positional representation
Author(s):
Zhenji Gao;
Xiaoming Wang;
Guanghong Zeng
Show Abstract
A new method named Landmark-based Qualitative Reference System (LBQRS) is introduced to express qualitative
positional information in this paper. LBQRS provides a dynamical positional framework. Under LBQRS, Qualitative
Coordinates (QC) is defined based on cardinal directional relations between target objects and one or several landmarks
adjacent to it. Formal model of LBQRS based on cognitive view of landmark position are presented. Formal description
and representation method are provided.
A new approach to geomagnetic matching navigation
Author(s):
Zhi-lei Ge;
Jun Zhou
Show Abstract
A new method of global optimal matching theory based on linear drawing of geomagnetic filed is proposed and
researched. Navigation system based on the geomagnetic field has no accumulated error, and it is not influenced by
weather, terrain and other factors as it is passive. Thus, geomagnetic navigation has good potentials to be an assistant
method for other navigation systems such as inertial navigation system. The matching navigation method avoids the
disadvantages of Kalman filter because it makes use of a set of relative information. In the literatures, the forming
principle of linear drawing is discussed. A necessary global optimal matching technique is researched because matching
a linear drawing with a standard planar chart results in infinite instances and the previous mismatch will affect the
following process. Correlation method is applied in the matching process for its simpleness. Genetic simulated annealing
algorithm is applied in the optimal researching process for its rapid convergence and global optimization. Mathematical
simulations are carried out to verify the correctness and efficiency of the new solution. The results are listed in the end,
which prove the rightness of the methods proposed in this paper.
Research and evaluation of Beijing-1 image fusion based on Imagesharp algorithm
Author(s):
Jianming Gong;
Xiaomei Yang;
Dong Han;
Dandan Zhang;
Hai Jin;
Zhenyu Gao
Show Abstract
Beijing-1 small satellite carries a 4m panchromatic sensor and a 32m multi-spectral sensor, with both the features of the
high resolution of SPOT and the multi-spectrum of Landsat. However, its resolution and the wavelength range of the
corresponding band are significantly different from the existing satellites. Meanwhile, the difference of the wavelength
ranges between the panchromatic image and the multi-spectral image is rather large, especially in the NIR band where
the difference reaches 80%. Thus, low correlation means that the traditional image fusion methods are not ideal to date.
Aimed at the spectral features of Beijing-1 small satellite high-resolution imagery and multi-spectral imagery, the paper
proposes an image fusion method based on Imagesharp. First, linear functions are used to fit the low-resolution image
into the high-resolution image, and then the fitted high-resolution multi-spectral image and the high-resolution
panchromatic image are fused, which can improve the spatial resolution and keep the original multi-spectral information
well at the same time. At last, in comparison to the traditional HIS and Brovey fusion method, Imagesharp method can
maintain the color saturation and the spectral information better. A large amount of experiments prove that Imagesharp
algorithm is suitable for the Beijing-1 image fusion and it is already specially applied in the Beijing-1 small satellite data
deep processing software.
Feature separability analysis for SAR ATR using data description method
Author(s):
Weiwei Guo;
Xiaoyong Du;
WeiDong Hu;
Wenxian Yu
Show Abstract
Feature extraction and selection play an important role in radar target recognition. This paper focuses on evaluating
feature separability for SAR ATR and selecting the best subset of features. In details, fifteen features extracted from T72,
BTR70 and BMP2 in MSTAR standard public dataset are examined, which are divided into seven categories: standard
deviation, fractal dimension, weighted-rank fill ratio, size-related features, contrast-based features, count feature,
projection feature, and moment features. Since the number of samples is small, a new separability criterion based on the
overlap degree of each two class regions is proposed to assess the separability of these features. Here the class region is
described by support vector data description (SVDD) method for good generalization. Based on the proposed criterion, a
forward feature selection method is adopted to choose the best subset of features. Because of the strong variability of the
feature against aspect, the features are analyzed under different aspect sectors within 360°angle range stepped by 15°, 30
°, and 60°, respectively. Experiments using MSTAR dataset validate the criterion, and the best subset of features is
determined.
On the performance of multicarrier direct sequence spread spectrum with band-limited Gaussian interference and multipath fading
Author(s):
Zezhou Luo;
Bin Ye;
Lier Bao
Show Abstract
Multicarrier spread spectrum (MC-SS) system employs frequency diversity, hence obtains the ability combating
band-limited interference. In this paper, we consider a multicarrier direct sequence spread spectrum (MC-DS-SS) system,
in which every sub-channel is spread by a pseudo number (PN) code respectively, making each sub-channel's bandwidth
larger than jammer's. The system has the advantages of large processing gain, low interception probability, and
robustness against partial band interference. We analyze bit-error ratio (BER) properties of MC-DS-SS system under
partial band interference, and compare it with single carrier DS system. It is shown by the comparisons that whenever the
diversity gain is observed, MC-DS-SS system always outperforms single carrier DS system under the same interference
environment. When jammer spreads its bandwidth over the entire frequency range of desired signal, MC-DS-SS still
outperforms single carrier DS-SS.
Propagation studying in cat-eye system for the beam affected by atmospheric turbulence
Author(s):
Yong Han;
Jian Wu;
Chunping Yang;
Wuguang He;
Guangyong Xu
Show Abstract
Cat-eye effect of opto-electric system plays a important role in the active detection, which was studied by many
researchers based on the geometric methods. But in practical application of it on the war field, the laser beam must be
affected by the atmospheric turbulence, which make the conventional method invalid. The main subject of this paper is
to study the properties of the laser beam propagation through the atmospheric turbulence and cat-eye system. A
procedure is outlined to numerically simulate the propagation of beam through them. The effects of cat-eye system on
the wave field disturbed by the atmospheric turbulence are analyzed.
Ranging error analysis in LFM radar under influence of Doppler frequency
Author(s):
Hongjun Hu;
Run Ni;
Hongbing Deng;
Dong Xu
Show Abstract
This paper, starting with the time and spectrum domain characteristics of the LFM pulse and its matched filter, analyzes
the ranging error generated by the Doppler frequency shift in the received signal, and presents a range error correction
model for the LFM pulse compression radar, which is proved applicable through further computer simulation and
tracking data analysis. Cautions are also proposed as to the practical engineering application of the correction equation.
The semantic description for Earth observation task of satellite
Author(s):
Shuguang Li;
Jianping Yuan;
Jianjun Luo;
Qiyu Wang
Show Abstract
This paper utilizes ontology to define and organize the information objects, data elements and their relations in the
domain of earth observation task of satellite. In this paper, we proposes a new method for building domain ontology of
earth observation task, it includes five steps: task definition, task disassembly, relation analysis, describing ontology and
ontology instantiation. The ontology-based method is effective and reliable for standardization and semantization of
earth observation task.
Analysis of intrasystem and intersystem interference of navigation systems with interplex modulation in the L1 band
Author(s):
Xufang Huang;
Xiulin Hu;
Zuping Tang
Show Abstract
The modernization of GPS and the Galileo system adopt the Interplex modulation to transmit multiple signals on one
carrier, Interplex modulation is a particular constant envelope phase modulation through induce the intermodulation (IM)
term. The main objective of this paper is to analyze the IM term effect degrees of interference that GPS and Galileo
signals are expected to have in the L1 band. This paper extends the interference assessing methodologies to be applicable
in the situation that accounting for IM term effects, and applies to analyze the impacts of Galileo IM term and the
impacts of three versions IM term signal of GPS. Numerical results show that different nonlinear mechanism of Interplex
modulation induce different degrees of interference, and the desired signals having different modulation models exhibit
different degrees of sensitivities to the IM term interference effects.
The study of high precision assistant navigation system with micro-magnetic sensors
Author(s):
Xuegong Huang;
Jiancheng Fang;
Lei Guo;
Yanwei Jiang
Show Abstract
Low-cost MEMS sensors often suffer from inaccuracy and are influenced greatly by temperature variation, and the
orientation error is cumulate with time. The GPS can provide long term stability with high accuracy, but it has its
insufficiencies, such as disturbed easy, lower data updating rate and so on, it is hard to meet the demand of real-time
measuring. The micro-magnetic sensors, an independence precision tool, can offer real-time yaw attitude angle, and this
can correct the orientation cumulate error, and it increase the independence in flight of the UAV. Based on analyzing the
selection principles of testing sensor, comparing 3 kinds micro-magnetic sensors, the GMI magnetic sensor is best to test
geomagnetic field. The Regional model of geomagnetic field is built, and a GMI-magnetic sensor navigation method is
put forward. Three-axis magnetic sensor measure the geomagnetic field, and it is matching with the geomagnetic map,
then the geomagnetic elements on currently position are knew, combining with the information of accelerometer, the
position information can be gotten by matching algorithm.
Research on automatic generalization methods of geographical spatial data based on semantic scale
Author(s):
Yongqi Huang;
Zhui Zhao;
Mengquan Wu;
Xiaochun Wu
Show Abstract
Scale is an important factor when people acquire laws of geographical phenomena and processes. Generalized scale
includes not only spatial scale and time scale but also semantic scale in geographic information science. Semantic scale
describes semantic change amplitude and hierarchy of attribute contents of geographic entities. Semantic change
amplitude represents attribute character changes in the unit time, the while hierarchy means classification and rank of
attribute description. Scale is in inverse proportion to detailed degree of geographic entities when GIS displays
multi-scale geographical spatial data. It is difficult that existing GIS display features of different semantic scale. As for
the classified or ranked geographical spatial data the optimal solution is the hierarchy or rank of geographic entities
displayed is higher when scale becomes small, so the generalization degree of detailed feature is higher.
Ontology is a kind of modeling tool of concept model that is able to represent information system at the semantics and
knowledge level. Geoontology is a kind of domain ontology and offers glossaries and relationships among concepts in
the geographic spatial information domain. As far as the geographical hierarchy and classification system is concerned
the relationships among the geographical concepts is hierarchy relationship, namely the relationship between the parent
concepts and the child concepts or between hypernyms and hyponyms. Geoontology can represent formally this
hierarchy relationship. A geographical concept can be navigated to its parent concept or child concept, and implements
the automatic generalization of geographic spatial data by merging the features in the geographical feature classes
corresponding to all child concepts of the some geographical concept in geoontology. However the automatic
generalization method based on the geoontology cannot smooth the linear features and the boundary of polygon features,
which should be implemented by resorting to other automatic generalization algorithms.
Quasi-dynamic electromagnetic scattering characteristic simulation and analysis of space satellite targets
Author(s):
Chaoying Huo;
Zhihe Xiao;
Hongmei Ren;
Hongcheng Yin
Show Abstract
The quasi-dynamic wide-band scattering characteristic modeling method of space object in orbit is given in this paper,
the dynamic wide-band electromagnetic scattering characteristic of a satellite is simulated significantly and we acquire
procedural image of scattering centers by accumulating high-resolution range profiles of satellite in flight. And we have
an idea that we can judge the structural information of satellite by the procedural image of scattering centers which
formed in flight. The simulation result show that the procedural image of scattering centers of satellite target is
connected with target's structure and it can be used to extract the structural information of satellite targets.
Missile geo-location using missile-borne SAR
Author(s):
Yu Liang Qin;
Bin Deng;
Hong Qiang Wang;
Xiang Li
Show Abstract
Missile borne Synthetic Aperture Radar can effectively improve the guidance accuracy of the Inertial Guidance System
of long-range missile. The basic principle of the missile geo-location is described at first. According to the range
equations and Doppler equations, the analytical mathematical expressions of the missile's position are deduced without
complicated and unstable iterations, and the detailed flow of the missile position solving is described. Based on
simulation, the effects of digital image matching, altitude and velocity errors on the geo-location accuracy are compared.
Image's concentric circle character matching based on lateral inhibition mechanism and application on scene matching
Author(s):
Fang Zi;
Yanjun Li;
Ke Zhang;
Dawei Zhao
Show Abstract
The lateral inhibition mechanism of biologic vision is introduced and applied on edge extraction of images. With the
method, the image's original characters are unchanged. Furthermore, the edge extraction and image enhancement can be
done effectively when the gray changes caused by varying illumination. For increasing the matching ability of resistance
to geometric distortion, a new matching algorithm is established. The edges of the real-time and reference maps are
extracted with the above-mentioned method based on lateral inhibition. Then the concentric circle characteristic vector of
image is defined and the method of vector extraction is proposed. The concentric circle characteristic vectors of the real-time
and reference maps are extracted. Finally they are matched according to the vectors. The resistance of geometric
distortion is improved. A map of roadway in a city obtained by satellite is simulated. The results show that the influence
of gray and geometric distortion on scene matching is effectively overcome. The algorithm is easily implemented with
hardware. The operation speed of the algorithm is also fast. It's worth for the design of real-time scene matching system.
Autonomous navigation based on x-ray pulsar timing
Author(s):
Dongsheng La;
Na Wang
Show Abstract
Celestial navigation is one kind of autonomous navigation technology which is suitable for navigation of deep space
rovers. Autonomous navigation technology based on X-ray pulsars is under development. It could provide an essential
backup navigation capability for missions that normally rely on GPS but have a need for continuity of operations in the
event of loss or denial of GPS. Radiation from X-ray pulsars is relatively easy to be detected and recognized. X-ray
pulsars provide with the potential to define a new time scale and frequency standard, they are nature reference
constellation for deep space navigation.
This paper introduces the principle of navigation based on X-ray pulsar timing. We also discuss the prospect of
navigation application using China radio telescopes.
Study on object recognition for satellite image
Author(s):
Xiaoping Chen;
Shengsheng Yu;
Zhilong Ma
Show Abstract
This paper presents the difference between object recognition for satellite image and general object recognition. To
overcome the difficulties of object recognition for satellite image, two methods are proposed in this paper. First, it is
shown that traditional moment invariants are no longer invariant while object shape is distorted or contour is blurry. This
paper proposes an improved invariable moment algorithm, which reconstructs seven invariants moment formulas, and
weakens the sensitivity on distorted border. Moreover, a 3D model database including all interested target's 3D model
can be established. When starting to recognize the target in satellite image, several 2D projection images can be retrieved
from the model database, using these images as recognition templates will be more accurate than using a single target
image. Experimental results show that the methods presented in this paper are effective on satellite image recognition.
An algorithm to generate DEM in rural areas from Lidar data
Author(s):
Xudong Lai;
Youchuan Wan
Show Abstract
According to the character of Lidar data in rural area, this paper presents a new algorithm to generate DEM in rural area.
The algorithm has fusion the distance information and intensity information to deal with the Lidar points. This paper
comes to a conclusion that it is theoretical and practical significant that this method is used to generate the DEM from the
Lidar data in rural area.
The algebraic solution of the double-system navigation equations
Author(s):
Hongwei Li;
Xiaolin Zhang
Show Abstract
One new method was brought forward to solve the algebraic solution to the double-system satellite navigation equations.
We established two binary quadratic equations about two satellite-station reference ranges and the matrix equations
about these ranges and receiver position, where two ranges were chosen from two systems respectively. Thus the original
problem is replaced by an approximate problem and for it two binary quadratic equations are obtained. Geometric and
clock information is used to discard the unwanted solutions. The reference ranges, system time biases and receiver
position were produced by solving these equations. Simulation indicates that our solution can solve the problem of initial
position when receiver cold starts in the situations of earth-bounded and deep space. Especially in deep space where the
conventional algorithm, which performs based on range-direction-cosine matrix, will probably converge to the wrong
solution, our solution is still correct. In earth-bounded situation, our solution has the same precision as the conventional.
Robot vision navigation based on a fly's compound eyes
Author(s):
Jiatai Li;
Ke Zhang;
Yanjun Li
Show Abstract
Method for navigation control of mobile robots under unknown environment is a important field of robotics. As few
transcendental knowledge is known, navigation control of mobile robots has many problem to be solved. In this paper,
we introduce the mechanism of a fly's vision and analyze the possibility of apply to robots navigation control. Then a
navigation method based on compound eyes is given. In the end, we give expectation and advices for future research.
Extended target detection based on generalized compound model in high resolution SAR images
Author(s):
Jiangyuan Li;
Jianguo Wang
Show Abstract
In high-resolution synthetic aperture radar (SAR) images, the target size may be much larger than the resolution of SAR
and the background clutter statistics are generally not Gaussian-distributed. But traditional constant false alarm rate
(CFAR) detection algorithm, which based on the Gaussian-distributed model, performs only one test cell at a time and
ignores the mutuality information with other cells in the target, so the performance of the CFAR detection algorithm can
be substantially degraded. In the paper, an extend target detection method based on the generalized compound model is
proposed. Unlike traditional CFAR detection method which distinguish test cell from the background only on the basis
of energy contrast, the extend target detection is sensitive to both the contrast and the distribution of the target. We
demonstrate the improved performance using the extend target detection method in the real high-resolution SAR images.
Information war countermeasures based on near space vehicles
Author(s):
Song Li;
Tong Xu;
Gang Wang;
Jiuyi Wang;
Weimin Li
Show Abstract
Analyzing air attacking environment countermeasures is the base of constructing near space vehicle information
platform. The study is significative to the development and application of near space vehicle information platform. The
main content of this paper is on information war measures and feasibility using near space vehicle.
Measuring error analysis of space Brillouin scattering based on edge detecting technology
Author(s):
Hong Lin;
Tianlin Dong;
Yong Ma;
Lin Jing;
Mengfan Liang
Show Abstract
Nowadays, the edge detecting technology based on Brillouin scattering signal has became the most advanced research of
lidar. This technology is widely applied to the areas of detecting atmosphere wind, space environment, and space objects
and so on. In this lidar system based on edge detecting technology, it is important to analyze measuring error. In order to
research measuring error, the space atmosphere channels are analyzed and the measuring error formula of detecting
Brillouin scattering frequency shift is educed. At the same time, Brillouin scattering echo signal received by the edge
detecting technology is estimated. A program is designed to simulate measuring error of detecting Brillouin scattering
frequency shift at different altitudes and with different Brillouin scattering frequency shift. From the simulation results,
we can find that in the ideal atmosphere conditions, the measuring error of Brillouin scattering frequency shift is less
than 20MHz at 100km height and less than 5MHz at 30km height in the atmosphere. Based on the results above, we can
draw a final conclusion: the edge detecting technology holds high signal-to-noise ratio and small measuring error.
Height corrected location algorithm analysis for emitter on Earth
Author(s):
Tingjun Li;
Xinjv Cai;
Shangao Li;
Guowei Wang;
Xiuli Zhao
Show Abstract
When three satellites for passive location are used, if the height of terrain where the target locate changes greatly and the
height is assumed constant the height error will be increased. So the Least-square estimation method is presented, at the
same time in the process of algorithm iteration the target height can be inquired in the geography information system and
be corrected continuously, and the localization error is analyzed and simulated, the result indicates that the corrected
height error can improve the height precision, then improve the level precision, the improved the level precision will
improve the height precision, then the integral localization precision can be improved.
A new method of cluster optimization design for scanned pattern interferometric radar
Author(s):
Tingwei Li;
Jubo Zhu;
Diannong Liang
Show Abstract
To deal with the contravention between the reversibility of the point spread function of scanned pattern interferometric
radar and the improvement of the azimuth resolution of the radar system, the paper presents a new method of cluster
optimization design. The method bases on the variability of the maximum spatial frequency number of the theoretical
formula of the array factor. By selecting an appropriate maximum spatial frequency number, we get a new aperture array.
The array designed by this method not only can get the desirable azimuth resolution but also can guarantee the
reversibility of the point spread function. Simulations validate the correctness of the method. At last, we also discuss the
applicability of the method.
A new fault detection and identification method for integrated navigation systems
Author(s):
Kun Liang;
Bin Wang;
Huli Shi
Show Abstract
At present, integrated navigation systems are frequently used for the navigation in the space. Compared with single
navigation, integrated navigation is improved in the functions, but the sensors in the system are more, the scale of the
system is enlarged, and the probability of failure in the system is increased. Once the fault appears, the loss is more or
less. So to ensure the liability of the system, some necessary effective steps are made for fault toleration. In other words,
the fault toleration scheme is very important for high precision and liability of the navigation system. Fault detection and
identification is the premise of fault toleration. Therefore a new integrated navigation system with a new fault detection
and identification method called GPS(Global Positioning System)/3DR system is proposed in the paper.
In terms of the characteristics and the most familiar fault types of navigation sensors, data of sensors at normal and fault
are simulated in the paper. Based on the traditional navigation system, a new integrated navigation with a new fault
detection and identification method is designed, and the system is verified by simulation. Finally by the comparison of
the typical integrated navigation system and the new integrated navigation system, the conclusion that the new integrated
navigation system is better than the typical one in three sides is achieved.
Improved frequency and time of arrival estimation methods in search and rescue system based on MEO satellites
Author(s):
Mo Lin;
Rui Li;
Jilin Li
Show Abstract
This paper deals with several key points including parameter estimation such as frequency of arrival (FOA), time of
arrival (TOA) estimation algorithm and signal processing techniques in Medium-altitude Earth Orbit Local User
Terminals (MEOLUT) based on Cospas-Sarsat Medium-altitude Earth Orbit Search and Rescue system (MEOSAR).
Based on an analytical description of distress beacon, improved TOA and FOA estimation methods have been proposed.
An improved FOA estimation method which integrates bi-FOA measurement, FFT method, Rife algorithm and Gaussian
window is proposed to improve the accuracy of FOA estimation. In addition, TPD algorithm and signal correlation
techniques are used to achieve a high performance of TOA estimation. Parameter estimation problems are solved by
proposed FOA/TOA methods under quite poor Carrier-to-Noise (C/N0). A number of simulations are done to show the
improvements. FOA and TOA estimation error are lower than 0.1Hz and 11μs respectively which is very high system
requirement for MEOSAR system MEOLUT.
Research on positioning mode of LADAR aided navigation system over plain area
Author(s):
Yi Lin;
Lei Yan;
Qingxi Tong
Show Abstract
Laser Radar (LADAR) achieves more applications on aerial aided-navigation in mountainous areas for its good
performance. But plain areas encounter terrain elevation's slow variation and occasional unavailability of Digital Feature
Analysis Database (DFAD), which as necessary reference. Looking for replaceable map source and extracting common
characters for matching, are the fundamental circles of imaging LADAR aided navigation research. In this paper aerial
high-resolution remote sensing (RS) images are applied as substitute for DFAD, and the edge factor is chosen out by
synthetically analyzing RS images' and imaging LADAR point cloud'scharacters. Then edge extraction algorithm based
on multi-scale wavelet is explored to reflect their common features, and weighted Hausdorff distance method is applied
to match for positioning. At last the high-resolution RS images and imaging LADAR data of the same area are assumed
for simulation experiment, which testifies the validity of the methods proposed above.
Fast image matching for localization in deep-sea based on the simplified SIFT (scale invariant feature transform) algorithm
Author(s):
Li Liu;
Fuyuan Peng;
Yan Tian;
Yiping Xu;
Kun Zhao
Show Abstract
Image matching is one of the most important issues in object localization algorithms, while stable feature detection and
representation is a fundamental component of many image matching algorithms. SIFT algorithm has been identified as
the most resistant feature extraction method to common image deformations. In this paper, we use SSIFT (Simplified
Scale Invariant Feature Transform) to solve the problem of image matching in non-structured underwater environments.
Like SIFT, we construct a Gaussian pyramid and search for local peaks in a series of difference-of-Gaussian (DOG)
images; however, instead of using local square image patch to assign orientation and build 128-element vector, we apply
local circle image region and build only 12-element vector for each keypoint. The experiments have shown that SSIFT
are more robust to image rotation, and more compact than the standard SIFT representation. We also present fast
matching results using such descriptors for non-structured underwater objects.
Study of quick orbital transfer technology for improving viability of remote sensing satellites
Author(s):
Qisheng Lu;
Zhigang Wang
Show Abstract
Non-coplanar circular orbital transfers based on the invariability of descending nodical local time is studied in this paper.
Based on minimum principle, both of the thrust direction and magnitude are optimized, regarding minimum total impulse
and final position and velocity constraints as the performance index on the assumption of fixed transfer time and
continuous thrust. The optimal transfer orbit is then obtained using conjugate gradient method. As transfer time is given,
a special initial condition for orbital transfers is determined, which ensures the invariability of descending nodical local
time. The validity of orbital transfer strategy adopted has been verified by simulation results.
Landform skeleton reconstruction from unorganized points
Author(s):
Mingliang Luo;
Guoan Tang;
Xuejun Liu;
Lu Bian
Show Abstract
Landform skeleton are lines that indicate significant topographic features of the terrain. It is widely used in mapping and
surveying, hydrology simulation, topography representation and engineering designing. In order to derive the landform
skeleton, many kinds of data source have been used, including digitized contour lines, Grid-DEMs and TIN. As time
goes by, more and more unorganized points have been acquired, created, maintained and disseminated in many fields.
Those unorganized points are the most original and important information which is vital for mapping and surveying.
How to extract the feature lines from unorganized points has been the hot-pot in computer design and reverse-engineering.
Methods used to extract landform features in existence have shown dependence on data types and
thresholds more or less. In the paper, the view sheds principle used to extract the feature points has been put forward and
then those points have been organized into feature lines according to related rules. The result has shown that the view
sheds principle can extract the features and give the levels of feature points.
Pure rotational Raman lidar based on wavelength division multiplexing technique for temperature profiling of the troposphere
Author(s):
Jiandong Mao;
Dengxin Hua;
Liaolin Hu;
Fei Gao;
Min Wu
Show Abstract
A new high-accuracy pure rotational Raman (PRR) lidar system at a laser wavelength of 532.25 nm, based on a
technique of wavelength division multiplexing (WDM), has been designed for profiling the atmospheric temperature of
the low troposphere. A special WDM, which was usually used in fiber communication field, is designed to separate two
PRR signals of N2 and O2 for temperature retrieval, and to simultaneously block Mie- and Rayleigh-scattering signals
with a rejection rate of large than 107. A numerical calculation is simulated to verify the feasibility of the lidar system,
and the results showed that the PRR lidar based on spectroscopic characteristic of the WDM is capable of measuring the
atmospheric temperature vertical profiles in the low troposphere, and a statistical temperature error less then 1K was
achieved up to a height of 3.3 km and 5 km for daytime and nighttime measurement, respectively, under conditions of
300 mJ laser energy, 25-cm-diameter telescope, 10 min observation time, solar radiance of 3×108 Wm-2sr-1nm-1 and
atmospheric backscattering ratio less then 3.4.
Evaluating operational effectiveness of electro-optical imaging reconnaissance satellite
Author(s):
Xin Ning;
Jianping Yuan;
Xiaokui Yue;
Balin Tian
Show Abstract
As an important part of operational effectiveness analysis of space-based system, the research on operational
effectiveness of electro-optical imaging reconnaissance satellite has great academic and realistic significance. In this
paper, we consider a certain scenario, in which a missile aided with an electro-optical imaging reconnaissance satellite
attacks a ground-based target. The operational effectiveness analysis and evaluating model of electro-optical imaging
reconnaissance satellite is built. The results of simulation demonstrate that operational effectiveness analysis and
evaluating model of electro-optical imaging reconnaissance satellite is feasible and reasonable. The models can be used
to analysis design, evaluating and development of space-based.
The algorithm and simulation for satellite navigation using x-ray pulsars
Author(s):
Li Qiao;
Jianye Liu;
Guanglou Zheng;
Liang He;
Zhi Xiong
Show Abstract
The X-ray pulsar is a special celestial source which possesses of the lighthouse effect in space. And its unique, stable and
predictable pulse can be utilized for satellite navigation and attitude determination. In this paper, the pulsar description is
presented to explain the properties conducive to satellite navigation. With the pulse phases detected at the satellite and
predicted at the initial reference location, the range measurements about the satellite can be generated. The Kalman filter
technology is used to combine the satellite dynamics and the range measurements. The simulation is provided to
demonstrate the expected performance of the satellite position and velocity determination using the observed phase
message within the Kalman filter.
ICA based blind multi-user detection method in CDMA navigation system
Author(s):
Junna Shang;
Zhijin Zhao;
Xiaorong Wang
Show Abstract
In this paper, the schemes which perform blind MUD, also called blind interference suppression, based on independent
component analysis (ICA) is proposed to be applied to GPS receivers. The ICA model is utilized mainly in blind
separation of unknown source signals from their linear mixtures. In CDMA navigation application only the source
signals which correspond to the coefficients of the ICA expansion are of interest. Simulation shows the method is more
effective than those usually used in GPS/Galileo and, thus, it has the potential of increasing the acquisition speed.
Confidence interval for space debris population estimation based on radar beam fence
Author(s):
Zhengxin Song;
Weidong Hu;
Yong Tao;
Wenxian Yu
Show Abstract
Estimating debris population is of great significance for assessing impact risk to spacecrafts, predicting the long-term growth potential and validating space debris models. A method of estimating the confidence interval for debris population using radar beam fence is proposed. The problem whether a debris object that may cross the beam fence, i.e. has large enough inclination and radar cross section, is actually detected is modeled as a (0-1) distribution. Using orbital altitudes measured, the average probability of crossing the beam fence is obtained. The confidence interval for debris population is estimated by the Central Limitation Theorem. Experimental results show the validity of the method.
A new subaperture chirp scaling imaging algorithm for spaceborne spotlight SAR
Author(s):
Jinping Sun;
Zhifeng Yang;
Wen Hong;
Shiyi Mao
Show Abstract
In order to overcome the azimuth spectrum folding occurrence in the spotlight imaging mode of the high resolution
spaceborne Synthetic Aperture Radar (SAR), we presented a new subaperture chirp scaling algorithm (CSA) in this
paper. Several phase functions of the extended CSA were modified according to the properties of subaperture processing.
These modifications make the new algorithm realize the precise recombination of the phase history data of each
subaperture without any additional computation load, making the subaperture overlapping and azimuth time extension
unnecessary. The validity of this new algorithm is proved through point target simulations by adopting TerraSAR-X
system parameters in the spotlight mode with 1m resolution and a swath of 10Km both in the range and azimuth.
LS-SVM based dim and small infrared target dualband fusion detection
Author(s):
Yuqiu Sun;
Shalan Li;
Jinwen Tian;
Jian Liu
Show Abstract
Aiming at the characters of weak and small targets in infrared images, an algorithm based on Least Squares Support
Vector Machines (LS-SVM) is presented to fuse long-wave and mid-wave infrared images and detect targets. Image
intensity surfaces for the neighborhood of every pixel of the original long-wave infrared image and mid-wave infrared
are well-fitted by mapped LS-SVM respectively. And long-wave and mid-wave infrared image gradient images are
obtained by LS-SVM based on radial basis kernels function. Fusion rule is set up according to the features of gradient
images. At last, segment fused image and targets can be detected with contrast threshold. Compared with wavelet fusion
detection algorithm and morphological fusion detection algorithm, when a target is affected by baits, the experimental
results demonstrate that the proposed approach in the paper based on LS-SVM to fuse and detect weak and small target
is reliable and efficient.
Autonomous navigation algorithm for spacecrafts based on dual quaternion
Author(s):
Kezhao Li;
Jianping Yuan;
Xiaokui Yue;
Qun Fang
Show Abstract
Celestial Navigation System (CNS), Inertial Navigation System (INS), Global Navigation Satellite System (GNSS), such
as GPS, GLONASS, GALILEO and Compass etc, and the integrations of them are some methods of autonomous
navigation for space. But these methods must be depended on the high speed links of the communications network.
Moreover, the precision of CNS is always worse, and can not meet the rigorous requirement of the space activities. INS
can not be used for long-term space navigation applications for its errors being accumulated. High accuracy can be met
by Carrier Differential Global Positioning System (CDGPS), but it is difficult to calculate the ambiguities of CDGPS.
Fortunately, autonomous relative navigation based on machine vision is a direction all over the world currently, and is
very suitable for autonomous spacecraft navigation because it has some advantages, such as low-cost, high precision,
autonomous ability, easy practicality etc. In this paper, on the basis of the attitude dynamics of spacecrafts and the theory
of machine vision, an autonomous relative navigation algorithm for spacecrafts based on dual quaternion and EKF is
proposed. The basis transform unit of this algorithm is feature line. Moreover, this algorithm is used to calculate both
relative position and attitude organically, and the disadvantages of those algorithms, in which, relative position and
attitude must be deal with separately, are overcome. Finally, the simulations show that this algorithm is an accurate valid
method for space navigation applications.
A method of land use/land cover change detection from remote sensing image based on support vector machines
Author(s):
Jiakui Tang;
Yincui Hu;
Xiuwan Chen;
Guangxia Li
Show Abstract
Land cover/land use has become one of the crucial but basic tasks in carrying out a series of important work. With the
development of remote sensing techniques and Geo analysis model, using remotely sensed data to monitor the status and
dynamical change of land cover/land use has become one of the most rapid, credible and effectual approaches. To
improve the accuracy of change detection from remote sensing image, this paper introduces a new method of change
detection from remote sensing image based on support vector machine (SVM), using multi-spectral remote sensing data.
We choose Hengshui city in China as a typical studying sample. The result shows that it is competitive with other
recently developed methods for change detection when applied to the same data sets and yield good performance with
very limited training data.
A novel analysis on code tracking performance of navigation receivers
Author(s):
Zuping Tang;
Xiulin Hu;
Xufang Huang;
Wei Hu
Show Abstract
This paper presents a precise expression to describe the RMS code tracking error of navigation receivers, which is
deduced under the following assumptions: the receiver code discriminator use coherent early-late algorithm or early-late
power algorithm; the additive noise with arbitrary spectrum is gauss distributed and is independent of signal; the code
tracking error is small enough to use the linear model. The theory is not restricted by bandwidth or ripple of receiver
front end. The simplified expressions are also presented in case of white noise only. Comparison between theoretically
predicted RMS code tracking error and simulation results are illustrated and validate the theoretical analysis result.
A study of instrument landing system on decimeter-wave
Author(s):
Lijian Shi;
Yongsheng Wang;
Dewei Wu;
Xiubin Zhao
Show Abstract
This paper puts forward a new type of landing system based on decimeter wave, in-depth analysis on the forming of
navigation information under this system, indicates the characteristics of the landing system, and defines the main
technologies; provides the approach to realize the landing system with the application of decimeter wave instruments,
puts forward the methods and the simulation of the generation of navigation signal and the establishment of antenna
array radiation pattern, providing the theoretical gist for the development of decimeter wave instruments landing system.
Fast reconstruction of instantaneous ISAR image based on FTFDS
Author(s):
Zenghui Li;
Feng He;
Jubo Zhu;
Diannong Liang
Show Abstract
Time-Frequency Distribution Series (TFDS), which achieves an effective balance between the time-frequency resolution
and the cross-term interference, can effectively reconstruct complicated maneuver targets' instantaneous ISAR images.
However, original algorithm is quite inefficient, and the approach to fast computation proposed in some literature cannot
be directly applied to engineering. In this correspondence, a straightforward realizable two-dimensional filter is derived.
Meanwhile, FTFDS, as the fast implementation of TFDS, is proposed based on the formula, and computational burden of
FTFDS is analyzed theoretically and experimentally in detail. The analysis of FTFDS indicates that FTFDS makes a
great advance of efficiency. As FTFDS fits parallel process, time-frequency analysis by FTFDS can be approximately
carried out in real-time. Simulated data processing has shown that FTFDS is practical and valid in fast reconstruction of
instantaneous ISAR imaging.
Automatic identification of earthquake-caused building harm based on image fusion
Author(s):
Haihui Wang;
Hui Du;
Minjiang Chen;
Aiping Cai
Show Abstract
This paper is to take the advantage of the imagery produced from QuickBird for damage identification in urban areas.
The buildings collapsed following the Bam earthquake. We present our study results in remote sensing image fusion of
identification of earthquake-caused building harm with HIS transform and intensity modulation. Commencing with the
inventory of buildings as objects within high resolution QuickBird satellite imagery captured before the event. The
number of collapsed buildings is computed based on the unique statistical characteristics of these buildings within the
'after' scene. The promising results from this analysis prove that improving spatial detail and spectral information could
be used as a potential methodology for automated identification of building damage.
Strapdown relative inertial navigation system design for a lunar rover
Author(s):
Liduan Wang;
Xingqun Zhan;
Yanhua Zhang;
Hongliang Xu
Show Abstract
To satisfy navigation demands for lunar rover operation in rough, unstructured terrain of lunar surface, a new strapdown
relative inertial navigation system (SRINS) is proposed in the paper. Inertial measurements data are generated based on
true trajectory of lunar rover and error models of inertial sensors (gyro and accelerometer), which are used to perform
high-fidelity simulations to validate the performance of SRINS and conventional SINS (strapdown inertial navigation
system) algorithms. Simulation results indicate that SRINS possesses the advantages like better accuracy, more simplicity and feasibility than the latter for lunar navigation. Moreover, the effects of inertial sensors' measurement errors on SINS precision are evaluated.
Studies on ship discrimination in polarimetric SAR images
Author(s):
Wenguang Wang;
Jun Wang;
Weiguang Chang
Show Abstract
Ship detection is an important application of SAR imagery. In this paper, a new discrimination method based on
morphological filter and the co-pol phase difference of the plarimetric SAR is provided. The parameter of co-pol phase
difference does not only indicate targets mechanism, but also can be extracted easily from HH channel and VV channel
of plarimetric SAR. The application based on the AIRSAR data shows that the new method is effective to discriminate
the false alarms in ship detection.
Scan mirror motion compensation technology for high accuracy satellite remote sensor
Author(s):
Zhigang Wang;
Shilu Chen;
Qing Li
Show Abstract
To acquire high quality image, the control system of the new generation Geostationary Meteorological Satellite in China
(GMSC) must have high pointing precision and degree of attitude stability, besides image navigation and registration
(INR) must be proceeded. This paper studies scan mirror motion compensation in image registration by using model
predictor method. In the study of model predictor method, the total technical case of scan mirror motion compensation is
designed; the analysis of the scan mirror motion disturbances is proceeded; and the compensated objects are ensured
through analysis of simulation; the model predictor mathematical model in scan mirror motion compensation model is
founded; the model predictor method compensated arithmetic is designed; the valid arithmetic of model predictor
method is proved through simulation. The research provides theoretical principles and practicable references to develop
the new generation GMSC.
Study on the model for wheat yield based on the electromagnetism information sources of ground objects and environments
Author(s):
Yan Tian;
Xin Zhan
Show Abstract
By analysis the model for wheat yield, the information sources of the wheat yield were obtained. Based on the discussion
for the relationship between electromagnetism information sources and yield factors of wheat, the methods to calculate
each yield factor of wheat are given and then provided the implementation and calculating procedures of yield model for
wheat. The most contribution of this paper is to present a novel theory---matter Electromagnetism Information Source
which has widely applications in both theory and practice.
A new multi-channel SAR-GMTI algorithm based on frequency STAP and FrFT
Author(s):
Jun Wei;
Yunneng Yuan;
Jingping Sun;
Shujun Liu;
Shiyi Mao
Show Abstract
A SAR-GMTI algorithm based on space-time adaptive processing (STAP) in frequency domain by multi-channel SAR is
proposed. The paper deduces the theoretical formula of the clutter suppression in-depth based on frequency STAP and
finds that the output is a chirp signal and similar to the input signal of the moving targets before suppressed, so FrFT is
chosen to detect them and estimate their moving parameters. The analyses in theory and simulator results show that our
new algorithm is effective.
Research on Fourier-Mellin transform for image matching aided navigation system
Author(s):
Hualing Wu;
Li Yan
Show Abstract
Image matching algorithm is the core of image matching aided navigation system. This paper has given a quick and
effective image matching algorithm based on Fourier-Mellin transform. It solves relative translation of two images by
calculating their peak value's position coordinates through inverse Fourier transform of power spectrum. A great deal of
experiments indicates that this matching algorithm has high precision and strong robustness. At last, a proposal was
advanced to image matching aided navigation system.
A new large-scale terrain real-time simplification algorithm based on Delaunay triangulation
Author(s):
Xianfeng Li;
Huixin Wu;
Huifeng Xue
Show Abstract
During the flyover of large-scale terrain, in order to eliminate the popping effect of switching among levels of detail and
to increase the frame rates with high image quality, a new bottom-up modeling strategy is put forward, which constructs
simplified terrain triangle mesh globally and updates mesh nodes dynamically. Hybrid culling technique based on blocks
and triangle faces and simplified computing method for screen-space errors are employed to select appropriate terrain
nodes rapidly. Then the Delaunay terrain mesh is updated by adding nodes, deleting nodes and modifying locally. At the
same time self-adaptive control for screen-space error tolerance is achieved during the terrain flyover. Results of
simulation experiments demonstrate that the algorithm eliminates popping effect effectively, and has a higher frame rate
compared with other algorithms. So it is particularly suitable for close-distance flyover simulation of large-scale terrain.
Design of integrated electronic chart pocket navigator system (PNS) and application for passage ship auto-track
Author(s):
Haigang Sui;
Jinghuan Xiao;
Anming Zhang;
Jie Luo
Show Abstract
With the development of hydrographical work and information techniques, digital charts are more and more popular in
maritime applications, and an embedded product--PDA (personal digital assistant) is widely used in navigation for its
smallness and portability. However, there is lack of PDA-based product which can provide integrated data management,
real-time alternate display and ship auto-track application based on traditional paper chart and s-57 ENC. Aiming at this,
some new techniques and algorithms including integrated spatial data management and display mode for ENC and paper
chart, multi-scale data organization, embedded chart navigation method based on GPS are presented. And the integrated
electronic chart pocket navigator system (PNS) based on PDA was developed.
Ship formation recognition based on information fusion of spaceborne IMINT and ELINT
Author(s):
Changfang Zhang;
Hongwen Yang;
Weidong Hu;
Wenxian Yu
Show Abstract
A method of ship formation recognition is proposed based on the information fusion of spaceborne IMINT (image
intelligence) and ELINT (electronic intelligence) in this paper. Firstly, the composition and the battle array of the
observed ship formation are derived from the spaceborne IMINT information of each individual ship. The beliefs about
the composition and the battle array of the observed formation are calculated separately. A synthetic evaluation method
is used to get the BPAF (basic probability assignment function) from IMINT information using the aforementioned two
beliefs. Secondly, by computing the matching measure between the observed emitter set and that of the typical formation
entity, the BPAF based on ELINT information is obtained. Thirdly, the two BPAFs based on the information of
spaceborne IMINT and ELINT are combined with DS (Dempster-Shafer) evidence theory. Finally, a decision is made
according to the combined BPAF. The experiment indicates that our proposed methods to obtain the BPAFs are
practicable and the formation recognition accuracy is greatly improved compared to the results which use only one of the
two sources.
The synchronization method for distributed small satellite SAR
Author(s):
Lei Xing;
Xiaochun Gong;
Wenxun Qiu;
Zhaowei Sun
Show Abstract
One of critical requirement for distributed small satellite SAR is the trigger time precision when all satellites turning on
radar loads. This trigger operation is controlled by a dedicated communication tool or GPS system. In this paper a
hardware platform is proposed which has integrated navigation, attitude control, and data handling system together.
Based on it, a probabilistic synchronization method is proposed for SAR time precision requirement with ring
architecture. To simplify design of transceiver, half-duplex communication way is used in this method. Research shows
that time precision is relevant to relative frequency drift rate, satellite number, retry times, read error and round delay
length. Installed with crystal oscillator short-term stability 10-11 magnitude, this platform can achieve and maintain nanosecond order time error with a typical three satellites formation experiment during whole operating process.
Technology progress in microelectronics promote on-board imaging of spaceborne SAR
Author(s):
Xinfeng Xu
Show Abstract
The realization of spaceborne SAR imaging on-board is a necessary trend for digital avionics in speedily advancing SAR
remote sensors. Powerful and efficient application-specific instruction-set processors (ASIPs) play a leading role in this
solution to keep data processing system functioning real-time. A few improving methodologies, technologies and
advanced EDA tools in microelectronics make it possible to design such a SAR imaging processor easier and faster.
Some evident and important delegates of them, including system-level modeling and simulation for SAR imaging
algorithm, available IP library designed by experts, ideas of designing domain-specific SoC with multiple processors and
the microelectronic ways to ruggedize avionics applied in space radiation-active environment, are presented heuristically
in this paper.
Classification based on the EMD of hyperspectral curve
Author(s):
Yiping Xu;
Kaoning Hu;
Jianxin Han
Show Abstract
Hyperspectral remote sensing, as a new remote sensing technology, provides a powerful measure to object identification
and classification accurately due to its acuminous ability of spectrum detection. This paper addresses the problem of the
classification of hyperspectral remote-sensing images, and studies a novel spectral matching method based on the
popular Empirical Mode Decomposition (EMD) technique. EMD is a new data analysis method by which any
complicated signal can be decomposed into a set of Intrinsic Mode Functions (IMFs). The IMFs express the tendency of
signals at different scales. In this method, spectral curves are decomposed with EMD, the IMFs are extracted and taken
as the comparing features for spectral matching and the minimum distance classifier is used to classify ground-objects.
The reason to take the IMFs as the comparing components is that the IMFs represent the intrinsic and stable component
of a signal. On the other hand, using IMF as comparing element is helpful to remove the effect of noise. Furthermore, to
improve the classification accuracy efficiently, similarity measure method and band selection scheme are introduced. The
experimental analysis has been carried out by using hyperspectral image acquired by the AVIRIS sensor on the
Washington DC Mall. The obtained results confirm the effectiveness of EMD in hyperspectral image classification with
respect to conventional classifications.
Ionosphere-isolating method for ground-based augmentation system
Author(s):
Rui Xue;
Jun Zhang;
Bing Du
Show Abstract
This paper describes a new method utilizing dual-frequency GPS data to improve the accuracy of Ground-based
Augmentation System (GBAS). With this so called ionosphere-isolating method, two dual frequency carrier-smoothing
filters are used to estimate differential correction and ionosphere refraction separately. By dual frequency filtering, the
filter in ground and airborne can be decoupled. By utilizing both of the two estimations, dual-frequency airborne user can
eliminate residual differential correction error imposed by ionosphere spatial gradient. A new GBAS architecture that
exploits ionosphere-isolating method to improve the accuracy of code differential systems is presented.
Realization of TV guidance gyro stabilized platform and research of control algorithm
Author(s):
Pu Yang;
Qi Li
Show Abstract
According to the special performance requirements of optoelectronic tracking equipments, a high-precision three-axis TV guidance gyro stabilized platform was designed and realized. The main techniques, including system construction, mechanical resonance and software and hardware implementation, were discussed and analyzed in details. Two hard cores of the system, the TV tracker and the servo controller, were investigated concretely. For the TV tracker, an improved correlation tracking algorithm was proposed and a fast search method based on image multiple resolutions was adopted, by which total computation time of the image processing system was decreased and the capability of target identification was enhanced. For the servo controller, a multiple closed-loops control structure was founded. To the problem of system nonlinear disturbances, some main disturbance-producing causes in the system were explored and a grey sliding mode control algorithm was proposed. With the control algorithm, the anti-disturbance capability of the system was increased effectively and the dynamic performance of the control system was ameliorated. The operating results of the platform show that the whole design of the system is appropriate and the control algorithms adopted are feasible and computationally efficient.
Binocular vision-based relative position and attitude measuring method between spacecrafts
Author(s):
Bin Ye;
Yuanyao Wang;
Qiuting Wang
Show Abstract
This paper introduces binocular vision measure principle, deduces the measure formulas of relative position and attitude
between spacecrafts, models binocular vision measurement system, and presents a novel kind of measuring method of
the relative position and attitude between spacecrafts. According to the variance model analysis of relative position and
relative attitude, under condition of camera calibration, the location matching error of feature points is the major reason
that arouses location measure error. Relative attitude is determined through the space location of feature points, therefore
attitude error also ascribe eventually the location matching error of feature points. The simulation results show that the
method can reach the need of measurement accuracy of the relative position and attitude for spacecraft, it is more
suitable in on-board real-time computation.
Navigation studies based on the ubiquitous positioning technologies
Author(s):
Lei Ye;
Weijie Mi;
Defeng Wang
Show Abstract
This paper summarized the nowadays positioning technologies, such as absolute positioning methods and relative
positioning methods, indoor positioning and outdoor positioning, active positioning and passive positioning. Global
Navigation Satellite System (GNSS) technologies were introduced as the omnipresent out-door positioning technologies,
including GPS, GLONASS, Galileo and BD-1/2. After analysis of the shortcomings of GNSS, indoor positioning
technologies were discussed and compared, including A-GPS, Cellular network, Infrared, Electromagnetism, Computer
Vision Cognition, Embedded Pressure Sensor, Ultrasonic, RFID (Radio Frequency IDentification), Bluetooth, WLAN
etc.. Then the concept and characteristics of Ubiquitous Positioning was proposed. After the ubiquitous positioning
technologies contrast and selection followed by system engineering methodology, a navigation system model based on
Incorporate Indoor-Outdoor Positioning Solution was proposed. And this model was simulated in the Galileo
Demonstration for World Expo Shanghai project. In the conclusion, the prospects of ubiquitous positioning based
navigation were shown, especially to satisfy the public location information acquiring requirement.
Approach of virtual observations generation of a multi-reference GPS station network
Author(s):
Guorong Yu
Show Abstract
The generation of virtual reference station observations to relay the corrections to the rover receiver for use with standard
RTK software is one of important architectures of reference station networks RTK positioning. The approach of virtual
observations generation based on a multi-reference GPS station network is presented in this paper. Ambiguities for the
baselines in the reference network are determined firstly. The inter-reference-station differential spatially-correlated
errors are estimated using highly accurate coordinates of the reference stations and resolved ambiguities. These
spatially-correlated errors are interpolated among the network region as corrections. These network-generated
corrections are used to correct the zero-differential observables of one reference station, which is usually the closest one
to the rover (the so-called primary reference station). These corrected zero-differential observables, named virtual
observations, are processed using conventional single reference station differential GPS algorithms. A test conducted
using regional reference networks in Jiangsu(China) demonstrates the effectiveness of the approach to reduce the time to
integer ambiguity resolution, and to increase the distance over which centimeter level accuracies can be achieved.
A knowledge-based segmentation technology for remote sensing optical images
Author(s):
Xiao Yuan;
Hongwen Yang
Show Abstract
In this paper, we propose a whole scheme of remote sensing image segmentation process, from fast detection to accurate
edge location. As we know, more structure information is acquired in high resolution remote sensing images. However,
traditional image processing algorithms will produce meaningless results without priori knowledge. We aim at solving
the problem in which regions may be distinguishable in intensity but belong to the same target by the ground truth. This
is done by multi-threshold segmentation. What's more, In order to get a more regular shape, we use random field model
to introduce spatial constraint at a small scale, and active contour model to smooth the whole edge at a larger scale.
Simulation results demonstrate the effectiveness of our method in extracting ships from the satellite images. This paper
also introduces the potential of integrating the image segmentation and subsequent image analysis tasks.
Development of flood routing simulation system of digital Qingjiang based on integrated spatial information technology
Author(s):
Yanbin Yuan;
You Zhou;
Yaqiong Zhu;
Xiaohui Yuan;
N. R. Sælthun
Show Abstract
Based on digital technology, flood routing simulation system development is an important component of "digital
catchment". Taking QingJiang catchment as a pilot case, in-depth analysis on informatization of Qingjiang catchment
management being the basis, aiming at catchment data's multi-source, - dimension, -element, -subject, -layer and -class
feature, the study brings the design thought and method of "subject-point-source database" (SPSD) to design system
structure in order to realize the unified management of catchments data in great quantity. Using the thought of integrated
spatial information technology for reference, integrating hierarchical structure development model of digital catchment is
established. The model is general framework of the flood routing simulation system analysis, design and realization. In
order to satisfy the demands of flood routing three-dimensional simulation system, the object-oriented spatial data model
are designed. We can analyze space-time self-adapting relation between flood routing and catchments topography,
express grid data of terrain by using non-directed graph, apply breadth first search arithmetic, set up search method for
the purpose of dynamically searching stream channel on the basis of simulated three-dimensional terrain. The system
prototype is therefore realized. Simulation results have demonstrated that the proposed approach is feasible and effective
in the application.
An image alignment based framework for ground vehicle tracking from an air-borne platform
Author(s):
Hong Zhang;
Fei Yuan
Show Abstract
Ground vehicle tracking is an important component of Aerial Video Surveillance System (AVS), which has important
military and civilian uses. This paper presents an image alignment based framework for ground vehicle tracking from an
air-borne platform, which can precisely track a pointed out vehicle and get back it when it reappear. We track a set of
point features of the selected vehicle by the technique of image alignment. An edge feature-based outlier rejection
criterion, a Kalman filter and a reappearance verification program are used to make the proposed tracking system
perform excellently under complicated conditions. Experimental results on real aerial images show that the proposed
framework is rational and robust.
Research on optical-odometer application in vehicle navigation system
Author(s):
Jinhong Zhang;
Xun Sun;
Suilao Li
Show Abstract
To get an accurate scale factor of optical odometer, a method aided by DGPS is proposed, and the error compensation for
the longitudinal position of optical odometer in vehicle navigation system is further studied. First, the tested data are
preprocessed. Although the resolution of optical odometer is less than 2mm, the output noise affected by vehicle shaking
attains to 2cm. Because of this, data is reconstructed based on kinematics analysis. The tested data are replaced with
reconstructed data if the difference is larger than a threshold. The results show that by this method, the precision of
ranging and speed can be improved efficiently, which is less than 0.002m and 0.04m/s respectively. If the output pulse
number of odometer and the travel mileage are known, the scale factor can be calculated. The error is obtained through
comparing the position data recorded by DGPS with the product of pulse number and the scale factor. It is shown that the
linear correlation is remarkable between the data of error and velocity. Therefore the first order model and second order
model are established. The compensated results indicate that the longitudinal positioning error can be controlled under 0.2m.
A quick route planning algorithm in vehicle navigation system
Author(s):
Ying Song;
Yanling Zhao;
Jing Zhang
Show Abstract
A quick route planning algorithm is proposed in the paper to improve searching efficiency and shorten calculating time.
In order to reduce the data of computing and storage, the road network is divided into several small road networks called
division road networks at first. The division road network is connected by boundary nodes and boundary edges. The start
point and the end point are belonging to different division road networks. Then, the shortest path among the start point,
the end point and boundary nodes is searched, the shortest path from the beginning point to the end point can be found
by combining these shortest paths. By dividing the road network, searching space is reduced and searching time is
shortened. Moreover, due to the shortest paths between boundary nodes are calculated and saved in computer in advance,
so the computing time is shortened a lot. In the end of the paper, a practical application example of the algorithm in realtime
vehicle navigation systems is given. The experimental results show that it's a good and efficiency way of
calculating the shortest path between two arbitrary points within the road network.
Design and realization of the baseband processor in satellite navigation and positioning receiver
Author(s):
Dawei Zhang;
Xiulin Hu;
Chen Li
Show Abstract
The content of this paper is focused on the Design and realization of the baseband processor in satellite navigation and
positioning receiver. Baseband processor is the most important part of the satellite positioning receiver. The design
covers baseband processor's main functions include multi-channel digital signal DDC, acquisition, code tracking, carrier
tracking, demodulation, etc. The realization is based on an Altera's FPGA device, that makes the system can be
improved and upgraded without modifying the hardware. It embodies the theory of software defined radio (SDR), and
puts the theory of the spread spectrum into practice. This paper puts emphasis on the realization of baseband processor in
FPGA. In the order of choosing chips, design entry, debugging and synthesis, the flow is presented detailedly.
Additionally the paper detailed realization of Digital PLL in order to explain a method of reducing the consumption of
FPGA. Finally, the paper presents the result of Synthesis. This design has been used in BD-1, BD-2 and GPS.
A study on the performance of partial correlation method under noise environment
Author(s):
Lu Zhang;
Qingjun Zhang
Show Abstract
The partial correlation acquisition for medium-long PN code is a fast acquisition method under high dynamic
circumstance. This article analyzes the performance of partial correlation method based on FFT to estimate the Doppler
frequency in the case of Gaussian noise environment, In this paper we take GPS civil signal L5 which has length of
10230 chips and a transmission rate of 10.23 MHz for example, deduce the formulas of the probability of false alarm and
probability of detection of this method and give the best subsection method at different Doppler frequency range through
simulation and theoretical analysis, with the simulation results in accord with theoretical analysis.
Landscape dynamics analysis of the Yongding River watershed (Mentougou section) by multi-temporal Landsat imagery
Author(s):
Yuhu Zhang;
Changqing Yu;
Jiaguo Qi;
Zili Zhang;
Qinshan Shi
Show Abstract
The problem of efficient use of multi-temporal remotely sensed data for land-cover and landscape pattern dynamics has
already considerable attention in landscape ecology and some other disciplines. This research develops and tests a
methodological approach to monitor and analysis landscape dynamics change of Yongding river watershed (Mentougou
section) as study area from 1988 to 2005, The result shows that the OIF is the best method of optimal bands selection in
Landsat TM remote sensing data, TM3, 4, 5 bands is optimal band combination ;the Mentougou Reach of Yongding
river watershed landscape changed significantly in terms of its composition over the period 1988-2005, The total
landscape patches of study area in 2005 are more those in 1988,2001, Mean patch size(MPS)decreased sharply, Number
of patches(NP) increased sharply, The landscape pattern takes on the fragmentation trends under the effect on the human
activity. The forest (woodland and shrubland)are the main landscape matrix. with a significant decrease in croplands and
a increase in built-up (residential, urban land) and industrial minerals mining land(coal, open-pit)over the 17 years, And
the underlying socio-economic and other drivers of landscape change in study area are discussed.
Hyperspectral RS image classification based on fractal and rough set
Author(s):
Yunjun Zhan;
Guangdao Hu;
Yanbin Yuan
Show Abstract
The multisperctral trait of hyperspectral RS is a new technology for RS image recognition and classification, on the other
hand, it is difficult to image processing owing to trait of data redundancy. This paper propose new method for
hyperspectral RS image classification. In order to reduce dimension, utilizing the hyperspectral RS's refined spectral
characteristic, we extract every pixel's spectral characteristic curve, and compute the fractal dimension of the curve. By
studying the relation between object and spectral characteristic curve and fractal dimension, the paper indicates that the
dilation fractal dimension is equal or close to same target wherever it locates, and different from different target. Then
based on every pixel's fractal dimension that interval is from 1 to 2, we stretch linearly the interval from 0 to 255, and
construct a new gray image. Lastly, we apply the approximate classing of rough set theory class to the new image, the result of classing is namely the result of hyperspectral RS image classification.
Clutter mitigation for space based radar by appropriate choices of array aspect ratio and radar PRF
Author(s):
Zenghui Zhang;
Lihua Liu;
Weidong Hu;
Wenxian Yu
Show Abstract
Different from the airborne scenario, space time adaptive processing (STAP) for space based radar (SBR) is a full system
design task whose performance is significantly determined by radar system parameters such as array aspect ratio and
PRF. To mitigate clutter, the two parameters should be appropriately designed. The suppression of mainbeam clutter is
discussed while taking the earth's rotation and high range foldovers into consideration. Clutter rank is derived by
modeling it as an equivalent two-dimensional spatially band-limited process and it is shown to be a function of array
aspect ratio and radar PRF. Relationships between clutter rank and the two parameters are analyzed. Optimal array
aspect ratio and radar PRF are obtained by minimizing clutter rank with the tradeoff of minimum discernable velocity
(MDV). A high fidelity modeling of SBR is given to illustrate the effectiveness of the method.
A high performance spatial modeling and simulation environment based on grid
Author(s):
Zimin Zhang;
Qi Li;
Xi Mao
Show Abstract
Multidisciplinary and multi-scale researches demand integrating different models usually created by different approaches
into an application. This gives a new challenge for spatial modeling and simulation, and promotes researches on
integrated modeling and simulation. Multi-paradigm modeling and modeling framework are two main categories of these
researches. The former implements integrated modeling in methodology level, and the latter in component level. This
paper presents a spatial modeling and simulation toolkit named SMSE that combines system dynamics and geoprocess to
provide an integrated modeling environment. The environment embeds ESMF, a widely used modeling framework, and
provides a graphical interface, which makes modeling much easily. To solve the time-consuming problem of spatial
simulation, a parallel processing environment is built on person computers under the support of grid technique, which
gives SMSE little hardware limits and better applicability.
Design and implementation of distributed virtual geographic environment system based on MAS
Author(s):
Jun Zhu;
Kaiping Zhang;
Xiaoxia Yang
Show Abstract
The use of distributed virtual geographic environments (DVGE) is one of the most promising uses of virtual reality in
geographic field. Multi-Agent Systems (MAS) is flexible and adaptive enough to resolve highly complex distributed
computing problems. This paper aims to discuss how to apply MAS technology to improve the efficiency of
collaborative work among multi-user. We firstly design the three-layer system architecture and multi agent system of the
DVGE. Then dynamic cooperative group algorithm is also addressed. Finally, we built a collaborative virtual
environment and implemented prototype system in silt dams system planning on a case study area, Jiu-Yuan-Gou
watershed of Loess Plateau, China. Experiment results prove that the scheme addressed in this paper is efficient and feasible.
Error floor behavior study of LDPC codes for concatenated codes design
Author(s):
Weigang Chen;
Liuguo Yin;
Jianhua Lu
Show Abstract
Error floor behavior of low-density parity-check (LDPC) codes using quantized decoding algorithms is statistically
studied with experimental results on a hardware evaluation platform. The results present the distribution of the residual
errors after decoding failure and reveal that the number of residual error bits in a codeword is usually very small using
quantized sum-product (SP) algorithm. Therefore, LDPC code may serve as the inner code in a concatenated coding
system with a high code rate outer code and thus an ultra low error floor can be achieved. This conclusion is also verified
by the experimental results.
Interference on the deep space Earth station systems from EESS satellites operating at the 8025-8400 MHz band
Author(s):
Shengbo Hu;
Xin Meng
Show Abstract
According to the ITU Radio Regulations and CCSDS Recommendation about radio frequency, the 8400-8450 MHz band
is allocated for Space Research Service (SRS) (category B) space-to-earth, and the 8400-8450 MHz deep space band is
critical to the success of deep space missions. Since the 8025-8400MHz Earth Exploration Satellite Service (EESS) band
is allocated for the downlinks of earth exploration satellites, the unwanted adjacent band emission may exceed the
protection criterion established by the ITU-R for the protection of the deep space earth stations by a large amount and
results in harmful interference to the deep space earth station systems. This paper first introduces a conceptual future
scenario with frequency bands. Secondly, the paper discusses the characteristics that are unique to the deep space
downlinks and then presents the characteristics of the EESS out-of-band interference to the deep space downlink X-band.
Finally, the paper describes the effects of the interference on the deep space earth station systems.
Software simulation platform for housekeeping of satellite
Author(s):
Meng Li;
Meng Yang;
Dong Liu;
Peng Li
Show Abstract
To design the simulation system of satellite housekeeping, and also to inject the robustness of unconventionality test
program for which realize the test of the validation and reliability of function of housekeeping software. Housekeeping
simulation system is based on instruction interpreter to complete interpretability of program. To be finished simulation
scheduling of external device interface module by Bus management. It is provided GUI integrated development
environment for debugging, and equipped with complete test data base and test tool chain. Significantly increase the
reliability of the satellite housekeeping software, shorten the cycle and costs of research and development.
Study on implementing delay tolerant networking for deep-space communication
Author(s):
Lixin Li;
Huisheng Zhang;
Guanzhong Dai
Show Abstract
Network applications must communicate with counterparts across disparate networking environments characterized by
significantly different sets of physical and operational constraints; wide variations in transmission latency are particularly
troublesome. The proposed Deep-Space Communication, which must encompass both terrestrial and interplanetary links,
is an extreme case. The Internet protocols are ill suited for this purpose. This article discusses the current research
challenges in the Deep-Space Communication, and identifies the fundamental principles that would underlie a delaytolerant
networking (DTN) architecture and describe the main structural elements of that architecture.
CVN software correlator applications in deep-space exploration
Author(s):
Weimin Zheng;
Fengchun Shu;
Dong Zhang
Show Abstract
Being able to achieve very high angular resolution, the Very Long Baseline Interferometry (VLBI) synthetic telescope is
widely used in the deep-space tracking. The software correlator is a novel VLBI data processing technique, which is very
suitable for deep-space exploration. This paper introduces the first 10-station software correlator of the Chinese VLBI
Network (CVN) and its applications. Based on the commercial symmetric multiple processor server, the CVN software
correlator can work in the near real-time and the post processing modes. Besides the normal VLBI data correlation
function, it has the abilities of fast fringe search, multi-channel phase calibration abstraction, high frequency resolution
which are especially useful in space craft tracking. It was successfully used in the European circumlunar explorer joint
tracking experiment and other space craft observations. More than one year operation indicated its characteristic of
flexible structure, reliability, scalability. It will be used in the Chinese lunar and other deep-space exploration projects.
Feasibility analysis on entanglement distribution in quantum repeater-based space quantum communication
Author(s):
Yu Liu;
Yue Li;
Fan Huang
Show Abstract
We give a feasibility analysis on entanglement distribution in quantum repeater-based space quantum communication.
After a quick review of the Quantum Repeater techniques, two typical communication scenarios are provided as
examples and a further feasibility analysis for entanglement distribution in general deep space quantum communication
on link requirements, transmission attenuations and terminal requirements are documented.
Equilibrium points in Earth-Moon system for continuous communication with far-side station and lunar orbiter
Author(s):
Hui Li;
Qinyu Zhang;
Naitong Zhang
Show Abstract
In order to continuous communication with lunar orbiter and even far side station at the back of Moon, Lagrange points
L1, L2, L4 and L5 is considered to be candidates for relay satellites or orbiters in the Earth-Moon restricted three body
system. Positions of Lagrange points in solar system including Earth-Moon system were calculated and missions before
and future around these points, especially Sun-Earth L1 and L2 were listed. Lagrange points satellites, orbiters and local
networks on the ground of a celestial body will constitute a planetary networks connected by an interplanetary backbone
in the whole architecture of Inter PlaNetary Internet.
Robust 2D fringe search algorithm for radio interferometry of very weak downlink signals of deep space probes
Author(s):
Fengchun Shu;
Xiuzhong Zhang
Show Abstract
The function of fringe search is to find the maximum amplitude of complex cross-correlation function and determine the
residual delay and delay rate with respective to correlator model. When the signals transmitted by deep space probes
have high SNR, the fringe search algorithm based on weighted least square estimation is very effective by tracking the
fringe phase without 2π ambiguities in the frequency and time domain respectively, but it is not suitable for very weak
signals when fringe phases include relatively large noises. According to VLBI data processing method for extra-galactic
radio sources, a robust 2D fringe search algorithm is proposed for radio interferometry of very weak downlink signals of
deep space probes. Compared with phase tracking fringe search algorithm, the proposed iterative process for searching
the maximum correlation amplitude is performed in the two dimensional delay and delay rate plane, which is insensitive
to large phase fluctuation in time and frequency domain, phase cycle ambiguities and phase outliers, so it is an optimal
algorithm and much more robust for very weak signals. It can be proved theoretically that the proposed algorithm is
equivalent to weighted least square estimation. Finally, fringe search for the VLBI observation of Mars Express is
presented by using a software program implementing the iterative algorithm.
Mobility performance analysis of an innovation lunar rover with diameter-variable wheel
Author(s):
Gang Sun;
Feng Gao;
Peng Sun;
Guoyan Xu
Show Abstract
To achieve excellent mobility performance, a four-wheel, all-wheel drive lunar rover with diameter-variable wheel was
presented, the wheel can be contracted and extended by the motor equipped in the wheel hub, accompanied with wheel
diameter varying from 200mm to 390mm. The wheel sinkage and drawbar pull force were predicated with
terramechanics formulae and lunar regolith mechanic parameters employed, furthermore, the slope traversability was
investigated through quasi-static modeling mechanic analysis, also the obstacle resistance and the maximum negotiable
obstacle height for different wheel radius were derived from the equations of static equilibrium of the rover. Analysis
results show that for the innovation lunar rover presented, it will bring much better slope traveling stability and obstacle
climbing capability than rovers with normal wheels, these will improve the rover mobility performance and stabilize the
rover's frame, smooth the motion of sensors.
Design of on-board parallel computer on nano-satellite
Author(s):
Zheng You;
Hexiang Tian;
Shijie Yu;
Li Meng
Show Abstract
This paper provides one scheme of the on-board parallel computer system designed for the Nano-satellite. Based on the
development request that the Nano-satellite should have a small volume, low weight, low power cost, and intelligence,
this scheme gets rid of the traditional one-computer system and dual-computer system with endeavor to improve the
dependability, capability and intelligence simultaneously. According to the method of integration design, it employs the
parallel computer system with shared memory as the main structure, connects the telemetric system, attitude control
system, and the payload system by the intelligent bus, designs the management which can deal with the static tasks and
dynamic task-scheduling, protect and recover the on-site status and so forth in light of the parallel algorithms, and
establishes the fault diagnosis, restoration and system restructure mechanism. It accomplishes an on-board parallel
computer system with high dependability, capability and intelligence, a flexible management on hardware resources, an
excellent software system, and a high ability in extension, which satisfies with the conception and the tendency of the
integration electronic design sufficiently.
Lunar soft landing rapid trajectory optimization using direct collocation method and nonlinear programming
Author(s):
Lianghui Tu;
Jianping Yuan;
Jianjun Luo;
Xin Ning;
Ruiwu Zhou
Show Abstract
Direct collocation method has been widely used for trajectory optimization. In this paper, the application of direct
optimization method (direct collocation method & nonlinear programming (NLP)) to lunar probe soft-landing trajectory
optimization is introduced. Firstly, the model of trajectory optimization control problem to lunar probe soft landing
trajectory is established and the equations of motion are simplified respectively based on some reasonable hypotheses.
Performance is selected to minimize the fuel consumption. The control variables are thrust attack angle and thrust of
engine. Terminal state variable constraints are velocity and altitude constraints. Then, the optimal control problem is
transformed into nonlinear programming problem using direct collocation method. The state variables and control
variables are selected as optimal parameters at all nodes and collocation nodes. Parameter optimization problem is solved
using the SNOPT software package. The simulation results demonstrate that the direct collocation method is not
sensitive to lunar soft landing initial conditions; they also show that the optimal solutions of trajectory optimization
problem are fairly good in real-time. Therefore, the direct collocation method is a viable approach to lunar probe soft
landing trajectory optimization problem.
Yesterday, today, and tomorrow of RAIM technology's development
Author(s):
Mengli Wang;
Shaowei Yong;
Feixue Wang
Show Abstract
RAIM (Receiver Autonomous Integrity Monitoring) is an autonomous integrity monitoring technology which fulfills the
fault's detection and isolation of the navigation solution in a receiver, based on the redundancies of observations. It has
been widely concerned and studied for the short warning time, the ability of detecting local user failures, and no need of
additional hardware resources and complex communication links with ground stations. The fundamental of RAIM is
introduced, and the key technologies such as methodology, availability, application and combination of RAIM with other
integrity technologies are summarized and analyzed. With the constructing of new generation GNSS systems, RAIM's
application is getting broader and broader. To improve RAIM technology and its availability, the future studies should be
concentrated on RAIM availability's augmentation, multi-failures monitoring algorithms, compatible systems' RAIM
and its availability and RAIM algorithms' extension.
3D optical interconnect mesh network for on-board parallel multiprocessor system based on EOPCB
Author(s):
Fengguang Luo;
Mingcui Cao;
Xinjun Zhou;
Jun Xu;
Zhixiang Luo;
Jing Yuan;
Liangjia Zong;
Yonghua Feng;
Chao Chen;
Conghui Zhang
Show Abstract
A three-dimensional (3-D) 4×4×4 optical interconnect Mesh network scheme for parallel multiprocessor system based
on polymer light waveguide electro-optical printed circuit board(EOPCB) is proposed in this paper. The Mesh
topological structures of light waveguide interconnects for processor element chip-to-chip on a board, and board-toboard
on backplane is constructed. The system consists of 64 processor element chips interconnected in a 3-D Mesh
network configuration. Every processor board comprises 4x4 processor element chips with Mesh interconnection.
Board-to-board Mesh interconnects are established on a backplane through light waveguide Mesh interconnect
topological structure. An additional optical layer with light waveguide structure is used in conventional PCB to construct
EOPCB. Vertical cavity surface emitting laser (VCSEL) array is used as optical transmitter array. PIN photodiode array
is used as optical receiver array. A MT-compatible direct coupling method is presented to couple light beam between
optical transmitter/receiver with light waveguide layer. The optical signals from a processor element chip on a board can
transmit to another processor element chip on another board through light waveguide interconnection in the backplane.
So 3-D optical interconnection Mesh network for parallel multiprocessor system can be reailzed by EOPCB.
Primary research on simulate proving ground design of lunar surface
Author(s):
Feng Gao;
Zhe Wang
Show Abstract
Beginning with the trials on lunar rovers' mobility, stability and trafficability, a research of simulate proving ground
programming design for lunar surface was performed. Based on the analysis of characters of lunar rovers, we put
forward a set of integrated and reasonable design of tests, which focused on over-obstruction, evade-obstruction,
distance-obstruction, as well as path planning of lunar rovers. At the same time, we provided systematic layout of
simulate proving ground, and clarified the detailed content of each sub-item. It affords basic knowledge of systematically
testing performance of lunar rovers, and it serves well for the lunar exploration.
Research on techniques for computer three-dimensional simulation of satellites and night sky
Author(s):
Guangwei Yan;
Haitao Hu
Show Abstract
To study space attack-defense technology, a simulation of satellites is needed. We design and implement a 3d simulating
system of satellites. The satellites are rendered under the Night sky background. The system structure is as follows: one
computer is used to simulate the orbital of satellites, the other computers are used to render 3d simulation scene. To get a
realistic effect, a three-channel multi-projector display system is constructed. We use MultiGen Creator to construct
satellite and star models. We use MultiGen Distributed Vega to render the three-channel scene. There are one master and
three slaves. The master controls the three slaves to render three channels separately. To get satellites' positions and
attitudes, the master communicates with the satellite orbit simulator based on TCP/IP protocol. Then it calculates the
observer's position, the satellites' position, the moon's and the sun's position and transmits the data to the slaves. To get
a smooth orbit of target satellites, an orbit prediction method is used. Because the target satellite data packets and the
attack satellite data packets cannot keep synchronization in the network, a target satellite dithering phenomenon will
occur when the scene is rendered. To resolve this problem, an anti-dithering algorithm is designed. To render Night sky
background, a file which stores stars' position and brightness data is used. According to the brightness of each star, the
stars are classified into different magnitude. The star model is scaled according to the magnitude. All the stars are
distributed on a celestial sphere. Experiments show, the whole system can run correctly, and the frame rate can reach
30Hz. The system can be used in a space attack-defense simulation field.
A carrier tracking technique based on a convex combination of two adaptive filters for EDL
Author(s):
Shengbo Hu;
Xiujuan Yao;
Na Zhao
Show Abstract
For planetary lander missions, the most challenging phase of the spacecraft-to-ground communications is during the
entry, descent, and landing (EDL). Due to the EDL events, the extreme acceleration and jerk cause extreme Doppler
dynamics on the signals received on Earth. In order to support spacecraft-to-earth communications during the EDL
phase, we develop a robust and low complexity carrier frequency estimation and tracking technique that is able to
operate under low SNR and highly non-stationary conditions, common to the adverse EDL scenario. The method
comprises two adaptive filters supervised by a convex combiner. By simulating, it is shown that the investigated convex
combination of individual adaptive predictors is able to outperform the best individual predictor.
Spacecraft's automatic landing control based on online tracing identification method of neural network
Author(s):
Jianling Zhang;
Jinwen An
Show Abstract
To improve the dynamical property and decoupling capability for a class of spacecraft system with strong coupling, a
neuron-network controller based on online tracing identification is established to meet the decoupling requirements of
multivariable system. The model with new structure and learning algorithm has significance for weight matrices and
makes training process of weights become more distinct and straightforward. The new neural network is then applied to
identification of nonlinear dynamics system, which the speed of learning and convergence is improved greatly for using
the priori input-output state knowledge. The results of simulation show that the neuron network decoupling controller
based on online tracing identification can effectively reduce the identification errors caused by the different sampling
data, and improve prominently the precision and the reliability of neural network in the system identification. The
controller has powerful self-learning and self-adaptive decouple capabilities.
A ROI-based deep space image compression algorithm
Author(s):
Cuifang Zhao;
Caicheng Shi;
Peikun He;
Yinli Zhang
Show Abstract
In order to satisfy the requirement of bandwidth and storage capacity, high efficient image compression coding method is
one of the key technologies. The general image compression methods only encode the original pixels without any
analysis. A deep space image compression algorithm based on the region of interest (ROI) is proposed in the paper. For
deep space exploration, only parts of the image are interested in depending on the application background. Some image
area such as secondary planet, star and satellite can be considered as ROI. The proposed method includes image
segmentation and different image compressions for different regions. The algorithm is characterized with higher image
signal noise ratio (ISNR) of the reconstructed image and lower computation complexity, and the image detail preserving
capability of the algorithm is better than that of JPEG2000. Because of its simplicity, fastness, and small storage, the
algorithm is easy to be realized in hardware and suitable for space borne application.
A blind watermarking algorithm based on HVS applied for covert communication
Author(s):
Fang Wei;
Jian Liu;
Hanqiang Cao;
Jun Yang
Show Abstract
There are two ways for transmitting data in a secure manner: Cryptography and steganography. Digital watermarking is a
specific branch of steganography, which can be used in various applications, including covert communication, owner
identification, authentication and copy control. In this paper, we proposed a blind adaptive watermarking algorithm
based on HVS is proper for covert communication. The secret information that can be seen as a watermarking is hidden
into a host image, which can be publicly accessed, so the transportation of the secret information will not attract the
attention of illegal receiver. With our approach, the secret information is embedded in the wavelet domain. By the
background luminance and the texture mask characters of HVS, we divide the wavelet coefficients of carrier image into
different classes. According to the classes of the wavelet coefficients the watermark image is embedded. The result of
our experimental shows that this approach is imperceptible and robust some image processing such as JPEG lossy
compression, cropping, median filtering, grads sharpening, Gaussian white noise attacks and so on.
A modification to GLRT-type SSME data rate estimation algorithm for deep space communication
Author(s):
Na Zhao;
Xin Meng;
Shengbo Hu
Show Abstract
NASA has been studying on a new technique called "autonomous radio" for radio receiver since 2004. In an autonomous
radio operation setting, one of the first parameters that we would like to estimate reliably would be the data rate of the
received signal. Knowledge of this parameter is required to carry out maximum-likelihood (ML) detection of other
parameters, such as the carrier phase or modulation type. Although ML estimation of the data rate itself is statistically
optimal, given that there is little knowledge of the incoming signal, this approach is often difficult if not impossible to do
in practice. But if one factor of data rate is mitigated for autonomous radio, the estimation of the data rate can be done
jointly with that of the SNR. NASA has presented two algorithms: SSME and GLRT-Type SSME. The GLRT-Type
SSME outperforms SSME. In this work, we make a modification to GLRT-Type SSME. By simulating, it is shown that
the modified algorithm is able to outperform the SSME and GLRT-Type SSME.
Reverse analysis and trustworthy control for operating system security
Author(s):
Wei Pan;
Weihua Li;
Gaozu Wang;
Jun Du
Show Abstract
Computing resources are susceptible to attack without guaranteeing security of operating system. It is necessary and
desirable for operating system to employ powerful safeguard to protect itself against diversified vulnerabilities. In this
paper, we present reverse analysis and trustworthy control for operating system security (RATCOSS), a novel approach
which uses reverse analysis and trustworthy control technologies to deal with security problems on the kernel level of
operating system. Our investigation aims to improve the ability to guard operating system against malicious attacks. The
proposed schemes demonstrate that our approach can effectively perform secure management of operating system.
Electromagnetic pulse bombs' defense
Author(s):
Bin Chen;
Yongbin Wang;
Juan Li;
Jianzhong Wang
Show Abstract
With the high power microwave devices development, the high power microwave electromagnetic pulse bombs (E-bombs)
have become practical abroad. The development of conventional
E-bombs devices allows their use in nonnuclear
confrontations. E-bombs are powerful enough to damage communication, radar, navigation and computer
systems. This paper discusses effects of EMP on electrical system and how to defend the EMP.
Simulation and research on security enhancement policies of space network protocols
Author(s):
Hengtai Ma;
Zhiguo Hong;
Dengke Zhu;
Gang Zheng
Show Abstract
In this paper, the state of the art of network protocols and security problems of space networks are firstly introduced.
Then, it analyzes some security protocols that can be applicable to satellite networks. To validate the effect of security
protocols in space networks, we use Stochastic Petri Nets (SPN) to model the communication process of Border Gateway
Protocol - Satellite version (BGP-S). Furthermore, by comparison and analysis, the effect of three security protocols on
average time delay is also analyzed from the SPN model with Stochastic Petri Net Package (SPNP) 6.0. What's more,
the policies on choosing security shemes are discussed. Finally, a NS-2-based simulation for BGP-S is implemented and
with the addition of security data flow test is made by comparison and analysis. Simulation results are basically in
accordance with the numerical results of the SPN model.
LMI-based H2/H∞ terminal proximity guidance algorithm for autonomous rendezvous and docking
Author(s):
Weiyue Chen;
Wuxing Jing
Show Abstract
In the terminal proximity stage of autonomous rendezvous and docking, H2 and H∞ and guidance algorithms are adopted to overcome the influence on relative guidance accuracy of the following terms, the uncertainty of the system model, the noise of the relative information measurements and thrust misalignment. First of all, a widely used glide slope scheme is introduced to plan the ideal terminal proximity trajectory. Using this assumption the ideal relative position and velocity can be determined beforehand. And then, the tracking error equations for V-bar approach are derived. So the guidance problem is transformed to synthesize a controller to eliminate the tracking error to zero. Modern control methods are applied to design the H2 / H∞ controller. The LMI (linear matrix inequalities) technology is adopted here to get the final solution for controllers. Simulation based on the solution obtained though MATLABRLMI toolbox is performed on a scenario of the rendezvous and docking final proximity stage. The simulation results verify the validity and superiority of the H∞ design method for the terminal proximity of autonomous rendezvous and docking.
Research on cooperative detection of UAV formation system based on multi-agent technology
Author(s):
Yong-jun Du;
Yong-jun Jin;
Han Li
Show Abstract
It is a reasonable and workable strategy, that multi-UAV can complement each other and cooperate closely, play fully the
comprehensive combat effectiveness of the UAV formation. The paper introduced multi-agent technology and
information fusion technology into the UAV formation system, constructed formation cooperative detection task
planning system and formation cooperative detection information fusion system, and analyzed their structure and
operating mechanism. In addition, combining responses of the UAV formation when facing unexpected threats, the paper
explored the cooperative detection strategy of the UAV formation. The research results also show some useful reference
for cooperative operations of the other multi-platform system.
Application of dead-reckoning in the single-base station location and tracking method
Author(s):
Ruyun Zhang;
Dandan Fan;
Mingyan Xu;
Ming Chen
Show Abstract
A location and tracking method utilizing Dead-Reckoning using single base station in cellular networks is proposed in
this paper. Extended Kalman Filter (EKF) and the location method utilizing the AOA and the variance ratio of AOA
are introduced to smooth the measurement error. The simulation result is illustrated to explain the location and tracking
efficiency of the proposed method.
Regional telecommunication satellite constellation design tradeoffs
Author(s):
Yujiang Zeng;
Xiulin Hu;
Xianhui Wang;
Ying Wang
Show Abstract
In this paper we proposed a new approach to design a telecommunication satellite constellation for regional coverage and
aiming at determining the best trade-off between maximal earth coverage and minimum delay of the satellite
communication. In this work, the nondominated sorting genetic algorithm 2 (NSGA-II) is used to generate sets of
constellation designs (Pareto fronts) that show the tradeoff for two pairs of conflicting metrics. A thorough parameter
analysis is performed on the NSGA-II for the constellation design problem so that the utility of the approach may be
assessed and general guidelines for use established. The results reported include the approximated Pareto fronts obtained
by the NSGA-II for the tradeoffs are discussed.
Robust control of hypersonic aircraft
Author(s):
Yong-hua Fan;
Jun Yang;
Yu-zhuo Zhang
Show Abstract
Design of a robust controller for the longitudinal dynamics of a hypersonic aircraft by using parameter space method is
present. The desirable poles are mapped to the parameter space of the controller using pole placement approach in this
method. The intersection of the parameter space is the common controller for the multiple mode system. This controller
can meet the need of the different phases of aircraft. It has been proved by simulation that the controller has highly
performance of precision and robustness for the disturbance caused by separation, cowl open, fuel on and fuel off and
perturbation caused by unknown dynamics.
A runway tracking model using Zernike moments and particle filters for a landing unmanned aerial vehicle based on vision
Author(s):
XinFeng Fan;
HongQun Wang
Show Abstract
An advanced runway tracking model for landing of Unmanned Aerial Vehicle (UAV) based on vision is proposed. This
model builds on existing work, but extends it to achieve efficiency, robustness, and address some critical situations such
as instant sun glare, instant heave fog, cloud hold back, and instant extinction of approaching marking, and so on. These
situations always have bad effects to our visual landing system of UAV. So, two different schemes containing several
approaches constitute the core of our visual system to address these situations. We use Zernike moments as a region-based
shape descriptor of runway and save the changing pattern through landing process of pretest. At the real flight
time, we use particle filter to track the change of the Zernike moments that calculated on each potential region of runway
at each frame. When this change is too big, exceed the threshold, we use the pretest data to reconstruct the shape of the
runway. The performance of the presented schemes has been assessed throuth processing several video sequences that
captured by the real landing plane. The experiment shows, this tracking model is more efficient and robust and can be
used on a vision sensor for landing equipment of UAV or for an aerial vehicle's aided system.
Survivability performance evaluation for satellite communication network based on Walker Constellation
Author(s):
Yu He;
Hongli Zhao
Show Abstract
Satellite communication plays a more and more important role in civilian communication and military communication
with the explosive growth of requirements on information. It also means that satellite communication network must have
a high survivability in order to provide satisfying services to its users. Network survivability reflects the ability of a
network to continue to function during and after failures. Now, many papers give an analysis to network survivability for
terrestrial networks and the papers studying network survivability for satellite network is few. This paper discusses the
network survivability for satellite network based on Walker Constellation. Firstly, we analyze the features of topology of
Walker constellation and the analysis method based on time segments is introduced. And then, the new survivability
measure for satellite network is defined based on topology structure and traffic capacity. At last, survivability function
for satellite network is introduced and some quantities of interest are gotten from the survivability function. Example of
survivability performance evaluation of Iridium satellite network is presented.
Security issues in satellite networks
Author(s):
Bibo Jiang;
Xiulin Hu
Show Abstract
Satellite networks have played an increasing important role in modern communication system for their flexible and
convenient feature. It is obvious that satellite communication systems tend to be hybrid networks and IP networks in the
future. They will provide data broadcasting services and Internet services. As in all other networks, security is a severe
challenge in satellite systems. In this paper, we construct a three-layer hierarchical satellite system and propose a
protocol for it. The protocol includes inter-layer security and end-to-end security. We apply asymmetric cryptography
and symmetric cryptography to provide security and efficiency as well. This protocol is also suggested to protect the
satellite network from eavesdropping, sophistication, masquerade and repudiation.
Transmission of optical signal in the plasma sheath of reentry vehicle
Author(s):
Hang Ji;
Yong Ma;
Chao Ma;
Lin Jing;
Hongyuan Wang
Show Abstract
To eliminate the communications blackout phenomenon of reentry vehicle during reentry, characters of the
communications channel of plasma sheath is studied. And based on the electron density and temperature of the sheath,
the transmission model of optical signal in plasma sheath is formed. Making use of the light transmission model in
plasma sheath to do simulation and calculation, the refraction and attenuation state can be got. It illustrates that the
influence of sheath to the transmission of optical signal is limited, and demonstrates the theoretical feasibility of light
communications in reentry communications.
A framework for space object surveillance based on the integration of space and Earth platforms
Author(s):
Peiquan Jin;
Zhigang Wu;
Shouhong Wan
Show Abstract
Space object surveillance takes a very important role in space defense and future space operation. In this paper, the state-of-
the-art of space object surveillance is first analyzed, in which the development of space object surveillance in U.S.A.,
Russia and Canada is mainly discussed. After a survey on space object surveillance in China, this paper propounds a
framework for space object surveillance based on the integration of space and Earth platforms. The intention of the
integration of space and Earth platforms is emphasized, and some key issues of the space object surveillance based on
the integration of space and Earth platforms are explored in detail.
Oil spill monitoring using MODIS data
Author(s):
Ying Li;
Yu Liu;
Long Ma;
Xijun Li
Show Abstract
Oil spills are seriously affecting the marine ecosystem. In order to implement an emergency in case of oil spills, it is
necessary to monitor oil spill using remote sensing. Spectral measurements are undertaken for several oil types in 1998
and 1999. Based on the oil spectral characteristics, this study demonstrates how MODIS (Moderate Resolution Imaging
Spectroradiometer) can monitor oil spills in an oil spill event occurred near Dalian in North China Sea. The study shows
that MODIS has possessed some hyperspectral characteristics, which improve the capability of oil spill monitoring.
A fuzzy call admission control scheme in wireless networks
Author(s):
Yufeng Ma;
Shenguang Gong;
Xiulin Hu;
Yunyu Zhang
Show Abstract
Scarcity of the spectrum resource and mobility of users make quality of service (QoS) provision a critical issue in
wireless networks. This paper presents a fuzzy call admission control scheme to meet the requirement of the QoS. A
performance measure is formed as a weighted linear function of new call and handoff call blocking probabilities.
Simulation compares the proposed fuzzy scheme with an adaptive channel reservation scheme. Simulation results show
that fuzzy scheme has a better robust performance in terms of average blocking criterion.
Modeling and simulation of micro-motion in the complex warhead target
Author(s):
Chao Ning;
Zhihe Xiao;
Chao Wang;
Hongcheng Yin
Show Abstract
The micro-motion dynamics induce the micro-Doppler effect. The rotating motion of radar targets is introduced, the
formulas of micro-Doppler for point-scatter model targets are derived, and some simulations for a warhead with a
sphere-head cone is given in the paper. After geometrical modeling and meshing, the static RCS of the sphere-cone is
calculated with PO+PTD. On the basis of the stationary modeling, a new method of quasi-dynamic electromagnetic
modeling is provided. The time domain returned signal of coning warhead could be simulated in this method, after
processing by time-frequency transform, the period of coning can be obtained. The simulation results are in agreement
with the theoretical result. The method by geometrical model is more accurate than point-scatters model.
Research on attacking strategy of many same missiles based on spatial transportation problem
Author(s):
Han Li;
Xianze Xiong;
Yongjun Du
Show Abstract
This paper researches the attacking strategy of many same missiles which are lauched from many different platforms to
many different targets by using the theory of Transportation Problem. The way how to build up the model is analysed:
the missiles are regarded as "transportation things", the launch platforms of the missiles are regarded as "production
places", the enemy's objectives are regarded as "destinations", then we can get attacking strategy. The solution
arithmetic of the model and the conditions that total transportation goods does not equal total output is simply explained.
And the common instance of the model "Assignment Problem" and it's solution is expressed.
Space target trace acquisition method of CCD serial images based on background elimination
Author(s):
Tongsheng Shen;
Chunhua Zhang;
Xuewei Wang
Show Abstract
One of the main tasks of Space Surveillance is space object detection and trace acquisition. The paper focuses on the
multi-target trace acquisition method of CCD star images, and put forward a target detection method based on
background elimination. The algorithm includes three steps. First is the pretreatment, every pixel whose gray value is
below the threshold will be set as a black pixel, the gray of which will be set as zero videlicet. Other pixels remain
invariable. Then, a frame of mask image is created based on addition of the serial images and morphologic dilation
operation. The mask can shield fixed stars and preserve the moving targets. In the following, a cross-projection method
is used in target domain determination. Finally, a target trace acquisition method is put forward. It has been proved that
the multi-target trace acquisition method can detect faint targets effectively in serial star images with high accuracy.
Development and visualization of the warning maps in the airborne multi-angle power line inspection system
Author(s):
Pengxin Wang;
Junming Liu;
Guangjuan Yan;
Kai Yan;
Wei Sun
Show Abstract
A parabola model is employed to fit high voltage power lines by using the remotely identified coordinates of the spacers
and tower corners of power lines. The shortest distance between land surface height at a pixel and heights of power lines
is defined as the warning index for indicating dangerousness of power lines. Three approaches on visualizing the
warning index map are developed and implemented in the Airborne Multi-angle Power Line Inspection System. The
visualization results show that the sliced color warning approach costs a relative low computing time, and can highlight
the dangerous warning sites, the fused color warning approach integrates land surface properties and the warning levels,
and the pseudo-color warning approach costs a relative high computing time and can be applied to visually interpret the
dangerousness by gradual color change.
A threat coefficient method for extended air defense system analysis
Author(s):
Zhihong Yin;
Naigang Cui;
Shiyi Guan
Show Abstract
The extended air defense system has been analyzed. The Particular attention is paid to the threat of the air defense
system to cruise missile. A method named Threat Coefficient Method was proposed based on the analysis of the air
defense system structure and its operations. A threat coefficient model of the air defense system was built. It is shown
that the threat coefficient will be reduced while threat-length is reduced by using the model. The threat-length has been
researched based on radar theory. The method has been verified by means of simulation. Based on the analysis, it is
found that reducing the RCS or increasing active chaff could reduce the threat coefficient.
Research of GPS integrity monitoring
Author(s):
Xia-qiong Yu;
Xu-rong Dong;
Bin Tang;
Xiao-yu Huang
Show Abstract
Integrity is one of the four basic parameters (accuracy, continuity and availability as the other three) which are used to
assess the performance of satellite navigation systems. This paper introduces the basic concept of integrity and analyses
the factors which affect the integrity of GPS. Focusing on the three main components of GPS and in terms of the object
to which integrity monitoring aims, the paper puts forward a new classification of the technology. The paper classifies
the technology into three categories, namely RAIM (Receiver Autonomous Integrity Monitoring), GIC (GPS Integrity
Channel) and SAIM (Satellite Autonomous Integrity Monitoring) and studies several typical methods of integrity
monitoring.
Using genetic algorithm to solve the parameters optimization problem of space maneuver vehicle rapidly approaching sub-orbit target
Author(s):
Qiyu Wang;
Jianping Yuan;
Zhanxia Zhu
Show Abstract
In this paper, we research a convenient method and its mathematics model of using space maneuver vehicle (SMV)
rapidly approach sub-orbit target. For minimizing the velocity impulse needs by the transfer orbit, an object function is
set up. Then we use a genetic algorithm toolbox GAOT to get the optimal result of this object function. Last, we simulate
the two situations; including the SMV's orbit parameters are known or unknown. These simulation results show that this
method can be used to find the rapidly approaching orbit which needs the minimal velocity impulse.
A new method of enhancing telecommand security: the application of GCM in TC protocol
Author(s):
Lei Zhang;
Chaojing Tang;
Quan Zhang
Show Abstract
In recent times, security has grown to a topic of major importance for the space missions. Many space agencies have
been engaged in research on the selection of proper algorithms for ensuring Telecommand security according to the
space communication environment, especially in regard to the privacy and authentication. Since space missions with
high security levels need to ensure both privacy and authentication, Authenticated Encryption with Associated Data
schemes (AEAD) be integrated into normal Telecommand protocols. This paper provides an overview of the Galois
Counter Mode (GCM) of operation, which is one of the available two-pass AEAD schemes, and some preliminary
considerations and analyses about its possible application to Telecommand frames specified by CCSDS.
A design proposal of a certain missile tactical command system based on Beidou satellite communication and GPS positioning techniques
Author(s):
Jian Ma;
Yongsheng Hao;
Jian Miao;
Jianmao Zhang
Show Abstract
This paper introduced a design proposal of tactical command system that applied to a kind of anti-tank missile carriers.
The tactical command system was made up of embedded computer system based on PC104 bus, Linux operating system,
digital military map, Beidou satellite communication equipments and GPS positioning equipments. The geographic
coordinates was measured by the GPS receiver, the positioning data, commands and information were transmitted
real-time between tactical command systems, tactical command systems and command center, by the Beidou satellite
communication systems. The Beidou satellite communication equipments and GPS positioning equipments were
integrated to an independent module, exchanging data with embedded computer through RS232 serial ports and USB
ports. The decision support system software based on information fusion, calculates positioning data, geography
information and battle field information synthetically, shows the position of allies and the position of enemy on the
military map, and assesses the various threats of different enemy objects, educes a situation assessment and threat
assessment.
An integration of GIS and virtual reality for visualization of large irrigated area spatial information
Author(s):
Cheng Wang;
Qing Jiang;
Lijun Li
Show Abstract
This paper introduces the application of geographic information systems (GIS) and virtual reality (VR) technology with
visualization of irrigated area spatial information in order to improve irrigated area information management and
presents a novel architecture for 3D irrigated area information management system. The functions of each module are
describes. Based on shule river basin informatization project, a practical application of system is introduced.
The design and implementation of geo-spatial database updating system based on digital map generalization
Author(s):
Renliang Zhao;
Jun Chen;
Donghua Wang;
Yaoling Shang;
Tinghua Ai
Show Abstract
Map generalization is very old topic, but the combination of map generalization technology with geo-spatial database
updating is relatively new. After the larger scale database is updated, the smaller scale database should be updated
correspondingly in order to keep the consistency of multi-scale geo-spatial database. In this situation, it is very
reasonable to apply map generalization technology into the process of geo-spatial database updating. This paper is
focused on the application map generalization into the updating of geo-spatial database. A method is described to update
geo-spatial database based map generalization technology in this study. The requirements of the application of map
generalization into spatial database updating are analyzed firstly. And then, the design is outlined and some key
technology details are emphasized on. Finally, the practical implementation in the national 1:50000 geo-spatial database
updating project is introduced. This study shows the method is less cost and more efficient in the multi-scale geo-spatial
database updating.
Azimuth estimate of ship with MUSIC algorithm
Author(s):
Liang Shan;
Ning Jin;
Lijun Chen
Show Abstract
A method of ship azimuth estimate with MUSIC algorithm is proposed in this paper. First of all, MUSIC algorithm is
expatiated. Then, MUSIC algorithm and Bartlett algorithm are applied to deal with underwater experimental data and
estimate the direction of arrival which can be used to figure out the azimuth of the ship. As a result, MUSIC algorithm is
a more effective method than Bartlett algorithm in estimating the azimuth of ship.
Spatial aggregation query in dynamic geosensor networks
Author(s):
Baolin Yi;
Dayang Feng;
Shisong Xiao;
Erdun Zhao
Show Abstract
Wireless sensor networks have been widely used for civilian and military applications, such as environmental monitoring
and vehicle tracking. In many of these applications, the researches mainly aim at building sensor network based systems
to leverage the sensed data to applications. However, the existing works seldom exploited spatial aggregation query
considering the dynamic characteristics of sensor networks.
In this paper, we investigate how to process spatial aggregation query over dynamic geosensor networks where both the
sink node and sensor nodes are mobile and propose several novel improvements on enabling techniques. The mobility of
sensors makes the existing routing protocol based on information of fixed framework or the neighborhood infeasible. We
present an improved location-based stateless implicit geographic forwarding (IGF) protocol for routing a query toward
the area specified by query window, a diameter-based window aggregation query (DWAQ) algorithm for query
propagation and data aggregation in the query window, finally considering the location changing of the sink node, we
present two schemes to forward the result to the sink node. Simulation results show that the proposed algorithms can
improve query latency and query accuracy.
A general stochastic regional movement model for hierarchical mobile IP and mobile satellite communication
Author(s):
Lier Bao;
Jiaolong Wei;
Zezhou Luo
Show Abstract
Combine the terrene mobile network and the mobile satellite communication to a total solution for mobile network
access. Use mobile satellite communication to cover the zone that terrene mobile network can not cover easily, and we
can treat the GSO as the GFA. Thus, we introduce a new mathematical model, which different with in PCS network, to
characterize the Boring Professor movement model for hierarchical mobile IP. The result given in this paper is very
useful for the cost analysis for location updating in mobile network.
A research on SLAM aided INS/GPS navigation system
Author(s):
Menglong Cao;
Pingyuan Cui
Show Abstract
Simultaneous Localization and Mapping (SLAM) aided INS/GPS navigation system is a landmark based terrain aided
autonomous integrated system that has the capability for online map building and simultaneously utilizing the generated
map to bind the errors in the Inertial Navigation System (INS) when GPS is not available. If GPS information is
available, the SLAM integrated system builds a landmark-based map using an INS/GPS solution. If GPS is not available,
the previously newly generated map is used to constrain the INS errors. The SLAM augmented INS/GPS system shows
two capabilities of landmark tracking and mapping using GPS information and more importantly, aiding the INS under
GPS denied situation. The validity of the proposed method is demonstrated by computer simulation.
A study on the scale of LU/LC status expression and data mining based on multi-grids
Author(s):
Yuhong Shan;
Xinyan Zhu;
Daosheng Du
Show Abstract
In the paper brings forward that complexity degree of land use structure can be used as one of quantitative indices to
define the land use/land cover (LU/LC) status expression precision scale. Then by simulating population density spatial
differences in Wuhan district, according to the value of complexity degree of land use structure, divides the experiment
area into a kind of non-uniform and multi-grid structure. Consulting one grid cells' status high or low in the multi-hierarchy
data structure, the LU/LC status expression precision scale rough or fine can be defined in a degree.
Furthermore, the outcome of simulating population density shows that the multi-grids land data structure can integrate
land use data with other social and economic statistics conveniently and neatly to complete some simple land data
mining tasks such as the data computation or analysis effectively, then can reflect the LU/LC status of some region.
Study of isoplanatic angle of dual-conjugate AO system in atmospheric turbulence
Author(s):
Xueke Ding;
Jian Rong;
Xiaochun Zhong;
Fang Li
Show Abstract
The limitation of classical AO and the basic principle of MCAO are briefly introduced. A dual-conjugate AO (tow-DM
MCAO) can offer a possibility of widening FOV characterized by the isoplanatic angle, Considering the application of
lidar, the isoplanatic angle's expressions of MCAO for uplink and downlink are deduced in this paper. And through
simulation, the conjugate height, the isoplanatic angle, the isoplanatic angle gain and the coherence length for
dual-conjugate system are thoughtfully discussed. The results show the conjugate heights play a great role in widening
the isoplanatic angle, and the isoplanatic angle retains maximum when the conjugate heights is at optimal altitudes. For
the ground lidar, the positions of optimal conjugate heights simulated are about 1 and 12 km, and the optimal detecting
height is 17 km. For the air-borne lidar, the isoplanatic angle gain is minimum at the height of 13 km, and fails to reach
an optimal detecting state, and the selection of the optimal conjugate height is relative with not only the coherence length
but also the height of air-borne system.
A movement based two tiers paging scheme for LEO mobile satellite systems
Author(s):
Yan Dong;
Jun Rao;
Xiaoyan Wang
Show Abstract
In LEO satellite mobile communication systems, location management plays an important role for the supporting of
global roaming and has great effect on the cost of mobility management. With the zooming satellite mobile users and
demands of communications, the diversity of terminal is increased and the speed range among terminals is also
proliferated. The speed of terminals is a crucial parameter for the design of location management strategy. A movement
based two tiers paging scheme for LEO mobile satellite system is proposed. Location area and paging area are defined
according to the classification of the terminal's speed respectively and one location area is divided into several paging
area for smaller quantity of location updating and shorter paging delay. The simulation is performed and the results show
the validity of the proposed paging scheme.
A new algorithm for successful ratio against command and guidance of early warning airplane
Author(s):
Ying Fu;
Rui Wang
Show Abstract
It is obvious that the function of the command guidance system for early warning airplane is a core position in the
modern war using high technique. The So the purpose of the paper is to introduce the basic concept and the algorithm
about the successful zone and the successful ratio of the command and guidance, when the space and the land are seen as
a system that obtaining controlling and using the battlefield information is effectively jointed with the automatic system
of the land command and guidance. And the applying military value is illustrated by the algorithm of the realistic example.
Analyze and research the integrated navigation technique for GPS and pseudolite
Author(s):
Gannan Yuan;
Xingli Gan;
Zhongyu Li
Show Abstract
To heighten the stability and precision of GPS positioning, the integrated navigation system for GPS and pseudolites
(GPS/PL) was set up. The nonlinear equation of pseudo-distance measurement was linearized by Taylor series expansion,
but it can't find any influencing factors of the truncation error. A new deducing method of the linear equation of
pseudo-distance measurement was put forward, and some influencing factors of the truncation error were found and the
nonlinear degree was defined. By the comparison of the nonlinear degree for GPS and pseudolites, the truncation error of
pseudolite was found much larger than that of GPS navigation during the linearization. In allusion to the stable flight
state of aircrafts, the nonlinear system equations of an integrated navigation system for GPS and pseudolites (GPS/PL)
were set up, and the unscented Kalman filter (UKF) was used to estimate the navigation parameters to solve the
nonlinear problems of PL. The simulation results showed that the maximum positioning error is 14 meters, and the mean
value is 7 meters. Thereby, the pseudolites make the enhancement for the positioning precision and system stability of
GPS navigation.
Bridging GPS outages using the optimal estimate to eliminate the position and velocity errors
Author(s):
Yichun Gao;
Jiancheng Fang;
Li Cai
Show Abstract
In this paper, a method is provided to bridge the outages of GPS with little computation load and easy application. In
order to solve the bridging problem, KF method is improved while GPS is in outage. And the bridging method is
provided based on the optimal smoothing. The simulation is given based on the fix-interval smoothing, and the results
show that the errors of position and velocity is eliminated after the method being taken. Finally, the conclusion is
discussed through an analysis between the simulation result and experienced application result.
A novel MAC protocol for mixed traffics in communication network in near space
Author(s):
Mingxiang Guan;
Qing Guo;
Lu Li
Show Abstract
A novel MAC protocol which was able to support data, voice and rt-VBR video traffics based on PRMA protocol was
proposed for communication network in near space. PRMA frame was divided into two parts, one part slots are allocated
for rt-VBR video and data traffics. The other part slots are allocated for voice traffic. The proposed MAC protocol had
good ability to support mixed traffics by means of optimized combination of slots in a frame, traffic separation and
traffic priority. Three performance parameters: voice and video packet loss probability, average delay of data packets and
channel utilization were analyzed in simulation. The simulation showed that the proposed MAC protocol had advantages
on increase of channel utilization with the guarantee of quality of service. Finally the optimized reservation time slots of
36 for rt-VBR video traffics and maximum channel utilization of 85% were given.
Application of hybrid wavelet neural network for missile fault diagnosis system
Author(s):
Jun Hu;
Guiyan Li;
Shaowen Jia
Show Abstract
In missile weapon system, exact fault prediction and diagnosis is very important for missile security, according to the
specialty and complexity of the missile fault diagnosis, a novel expert system design method based on the hybrid neural
network ensembles is proposed in this paper. To improve the limitation of applying traditional fault diagnosis method to
the diagnosis method of the diagnosis of missile fault, with large amounts of typical missile fault samples and raw
measurable parametric data available, the missile fault diagnosis system based on wavelet neural network ensembles can
be created applying general construction techniques of the wavelet neural network fault diagnosis system, including
signal binary wavelet transform, fault feature extraction/selection and network training. The back-propagation (BP)
algorithm is used to fulfill the parameter initialization and the neural network structure (WNN). By means of choosing
enough practical samples to verity the wavelet neural network (WNN) and the information representing the faults is
inputted into the trained WNN, and according to the output result the type of fault can be determined. It's proved that
through diagnosis of the missile from several different sides by use of different parameters the diagnosis result is more
reliable. The method can be generalized to other devices' fault diagnosis.
Study on reduced-dynamic orbit determination of low Earth orbiters
Author(s):
Bao-min Han
Show Abstract
Some orbit determination methods using onboard GPS Observations were discussed firstly in this paper, especially the
principle and mathematical model of reduced-dynamic Precise Orbit Determination (POD) of Low Earth Satellite (LEO)
based on undifferenced spaceborne dual-frequency GPS data. Then a weeklong (from July 28, 2003 to August 3,2003)
dual-frequency onboard GPS observation from CHAMP satellite was computed using reduced-dynamic POD. Compared
with TUM solutions, our CHAMP orbiting results of one week using reduced dynamic POD method are within 8
centimeters, which can meet the requirements of some higher precision orbit satellite orbits. In order to obtain high
precision orbiting results, the impact of different gravity models and proper interval of pseudo-stochastic-pulses on the
orbit determination accuracy were analyzed as well.
A new FOA estimation method in SAR/GALILEO system
Author(s):
Gang Liu;
Bing He;
Jilin Li
Show Abstract
The European Galileo Plan will include the Search and Rescue (SAR) transponder which will become part of the future
MEOSAR (Medium earth orbit Search and Rescue) system, the new SAR system can improve localization accuracy through measuring the frequency of arrival (FOA) and time of arrival (TOA) of beacons, the FOA estimation is one of the most important part. In this paper, we aim to find a good FOA algorithm with minimal estimation error, which must be less than 0.1Hz. We propose a new method called Kay algorithm for the SAR/GALILEO system by comparing some frequency estimation methods and current methods using in the COAPAS-SARSAT system and analyzing distress beacon in terms of signal structure, spectrum characteristic. The simulation proves that the Kay method for FOA
estimation is better.
Effect analysis of aerospace environment for the application of satellite navigation system
Author(s):
Dewei Wu;
Jing He;
Chuanjin Dai;
Kaifeng Yu
Show Abstract
With the widespread application of satellite navigation system, for aerospace vehicle guiding and navigation, the study
on application affect of satellite navigation system in aerospace is of great value to provide navigation services better and
satisfy the high accuracy navigation and guiding requirement of aerospace vehicle. This paper put emphasis on the
influence on satellite navigation system positioning performance caused by geometrical, dynamic, physical and
electromagnetic environment of aerospace. The work of this paper can provide a good idea and direction for subsequent
deep research.
A novel key distribution scheme for securing satellite IP multicast
Author(s):
Zhan Huang;
Qing Guo;
Xuemai Gu
Show Abstract
How to improve the efficiency of key distribution is one of the emphases in the research area of satellite IP multicast
networks in recent years. This paper presents a novel framework based on layered principle. This scheme divides
original monolayer multicast key distribution structure into two layer, and makes rekeying modification happen only on
its encapsulated individual group layer. A modified LKH based on member behavior activity is also proposed to
decreases the amount of key update information transmission. So, this scheme can realize rapid rekeying by decreasing
message transmission amount via satellite links and saving limited bandwidth resources, so as to provide significant
performance gain for satellite multicast system. The simulation curves indicate that, compared with monolayer LKH
mechanism in satellite multicast, our proposal is definitely advantageous in the condition of frequent join-leave,
especially when the quantity of join member and leave member are about equal. So, it is concluded that the proposed
key distribution scheme can provide scalability and high performance for large dynamic satellite multicast.
An improved method of continuous LOD based on fractal theory in terrain rendering
Author(s):
Lan Lin;
Lijun Li
Show Abstract
With the improvement of computer graphic hardware capability, the algorithm of 3D terrain rendering is going into the
hot topic of real-time visualization. In order to solve conflict between the rendering speed and reality of rendering, this
paper gives an improved method of terrain rendering which improves the traditional continuous level of detail technique
based on fractal theory. This method proposes that the program needn't to operate the memory repeatedly to obtain
different resolution terrain model, instead, obtains the fractal characteristic parameters of different region according to
the movement of the viewpoint. Experimental results show that the method guarantees the authenticity of landscape, and
increases the real-time 3D terrain rendering speed.
Study on the GPS/MM navigation method based on the vehicle kinematic model
Author(s):
Chuan-jun Li;
Qing Wang;
Zhuangsheng Zhu;
Zengshe Guan
Show Abstract
By using the vehicle kinematic model of "current" statistical model, based on the map-matching, the current speed and
direct of the vehicle on the road are obtained. The vehicle's next position is calculated by the dead reckoning and the
GPS data is verified. The result of the car experiment on the road shows that the precision, the real dynamic performance
and the reliability of the GPS system on the car are improved, and so are the GPS multi-path effect. It also shows that the
technology can realize the vehicle navigation system to locate in blind area of GPS. And the technology has its
practicability in some way in the case of that the simple GPS takes up the main field of the vehicle navigation system.
Applying nonlinear filter to TCM-8PSK satellite data transmission system
Author(s):
Jun Liu;
Jing Li;
Zhen Fang Liu;
Rong Jun Shen
Show Abstract
A design applying nonlinear filter to trellis coded modulation (TCM) 8PSK satellite data transmission system is
presented. The tracking performances included tracking range and tracking precision are better than the one using linear
filter.
Dynamic cross-layer bandwidth allocation scheme for broadband satellite network
Author(s):
Lu Li;
Qing Guo;
Mingxiang Guan;
Min Jia
Show Abstract
The traditional bandwidth allocation schemes are based on layered design. They solve the problem at Medium Access
Control (MAC) layer only and do not consider the variable channel state and Quality of Service (QoS) of traffic flows
which will influence the performance of bandwidth allocation scheme seriously. This paper proposes a cross-layer
bandwidth allocation scheme for the broadband satellite network which supports the transmission of voice traffic and
Internet data. This scheme combines the QoS of traffic flows at application layer and the channel state of the physical
layer with the bandwidth allocation scheme in a cross-layer optimization. The master station computes a cost function
that considers all the relevant parameters and gets the most efficient bandwidth assignments through dynamic
programming algorithm. Numerical results show that the proposed scheme can adapt to variable channel state and
increase the goodput of Internet data as much as possible without deteriorating the QoS of voice traffic.
The GPS code acquisition based on pipelined FFT processor
Author(s):
Wei Li;
Haibing Zhu;
Jun Wang;
Shaohong Li
Show Abstract
This paper describes one implementation of the long PN codes acquisition especially for GPS P(Y) code direct
acquisition. The design method is based on the parallel method using the ultra long FFT (Fast Fourier Transform) based
processing which searches over time uncertainty in parallel and frequency uncertainty serially. The FFT processor is
based on R22SDF (single-path delay feedback) pipelined FFT architecture for its least memory use. The design was
implemented with the FPGA device, and is tested and verified with the simulated GPS P code. The system can search in
less than 60 seconds over 2.5 KHz of frequency uncertainty and 1 sec of time uncertainty with the work speed higher
than 100MHz.
GIS spatial analysis applied to soil and water conservation aided planning and design
Author(s):
Xianqi Li;
Zhiyuan Zeng;
Yongchuan Zhang
Show Abstract
GIS based Soil and Water Conservation Aided Planning and Design (SWCAPD) is a crucial component for soil and
water conservation monitoring and information management system, which provides decision support for small
watershed soil and water conservation. GIS affords effective method to manage a large amount of spatial and attribute
information about a small watershed, meanwhile, it is significant to discover potential topographical information using
GIS spatial analysis. Topographical information includes elevation, slope and aspect and so on, which provides proofs
for planning measures. Land use patches layer is regard as the basic cell for planning and design, and the accuracy of
patches layer topographical information directly influences the planning result. On the basis of paper relief maps, DEM
is obtained after a series of data processing, and it will be clipped by land use patches layer. Finally patch topographical
information is acquired and stored. Aided decisions for planning measures are made after combining the acquired
topographical information to expert rules and foundation data. The function framework of SWCAPD is given in this
paper, and it is implemented aiming to a certain small watershed.
Terrain mechanical parameters online estimation for lunar rovers
Author(s):
Bing Liu;
Pingyuan Cui;
Hehua Ju
Show Abstract
This paper presents a new method for terrain mechanical parameters estimation for a wheeled lunar rover. First, after
deducing the detailed distribution expressions of normal stress and sheer stress at the wheel-terrain interface, the
force/torque balance equations of the drive wheel for computing terrain mechanical parameters is derived through
analyzing the rigid drive wheel of a lunar rover which moves with uniform speed in deformable terrain. Then a
two-points Guass-Lengendre numerical integral method is used to simplify the balance equations, after simplifying and
rearranging the resolve model are derived which are composed of three non-linear equations. Finally the iterative method
of Newton and the steepest descent method are combined to solve the non-linear equations, and the outputs of on-board
virtual sensors are used for computing terrain key mechanical parameters i.e. internal friction angle and press-sinkage
parameters. Simulation results show correctness under high noises disturbance and effectiveness with low computational
complexity, which allows a lunar rover for online terrain mechanical parameters estimation.
A new blind nulling algorithm for CDMA mobile satellite communication systems
Author(s):
Yunzhi Liu;
Huali Wang;
Zhihui Wang
Show Abstract
A new anti-jamming method is proposed combining adaptive array with direct sequence spread spectrum (DSSS)
techniques in mobile satellite communication system. Different with the conventional depreading process, the proposed
method modifies DSSS despreador, in which the output data are blindly processed. It overcomes the problem that DSSS
signal often has very lower SNR, which is difficult to be captured in constant modulus array processing, especially when
strong interference/jamming signals exist coincidentally.
Uncertainty in spatial data mining
Author(s):
Kun Mei;
Yangge Tian;
Fulin Bian
Show Abstract
Spatial data mining, i.e., mining knowledge from large amounts of spatial data, is a demanding field since huge amounts
of spatial data have been collected in various applications. The collected data far exceeds people's ability to analyze it.
Thus, new and efficient methods are needed to discover knowledge from large spatial databases. Most of the spatial data
mining methods do not take into account the uncertainty of spatial information. In our work we use objects with broad
boundaries, the concept that absorbs all the uncertainty by which spatial data is commonly affected and allows
computations in the presence of uncertainty without rough simplifications of the reality. And we propose an uncertainty
model that enables efficient analysis of such data. The study case of suitable flounder fishery search indicates the benefit
of uncertainty research in spatial data mining.
Spatial decision support system for tobacco enterprise based on spatial data mining
Author(s):
Xin Mei;
Junyi Liu;
Xuexia Zhang;
Weihong Cui
Show Abstract
Tobacco enterprise is a special enterprise, which has strong correlation to regional geography. But in the past research
and application, the combination between tobacco and GIS is limited to use digital maps to assist cigarette distribution.
How to comprehensively import 3S technique and spatial data mining (SDM) to construct spatial decision support
system (SDSS) of tobacco enterprise is the main research aspect in this paper. The paper concretely analyzes the GIS
requirements in tobacco enterprise for planning location of production, monitoring production management and product
sale at the beginning. Then holistic solution is presented and frame design for tobacco enterprise spatial decision based
on SDM is given. This paper describes how to use spatial analysis and data mining to realize the spatial decision
processing such as monitoring tobacco planted acreage, analyzing and planning the cigarette sale network and so on.
GPS based detection of pre-seismic ionospheric abnormality
Author(s):
Yang Meng;
Zemin Wang;
Dongchen E;
Jingbin Liu
Show Abstract
Ionospheric abnormality before the 26 December 2004 M9.3 Sumatra earthquake is detected by the total electron content
(TEC) of ground-based receivers of the global positioning system (GPS) in the Indian Ocean area. Higher spatiotemporal
grids of VTEC than earlier research are computed. To identify the abnormal ionospheric-seismic signals before
the earthquake, a method of statistical analysis is utilized, and the temporal solar activity and geomagnetic environment
is also considered in this paper. Results indicate that VTECs mostly decreased 4 days before earthquake happening, and
quickly come back after the tragedy. We also find that areas of ionospheric-seismic anomalies is in ±15° latitude deviate
from epicenter, and the anomalies are more obvious in the sea than the earth, so we can deduce that correlations of
ionosphere with seabed and earth are different to some extent.
Urban spatial information services based on service-oriented grid architecture
Author(s):
Naixia Mou;
Lingxian Zhang;
Bo Ai;
Wenbao Liu
Show Abstract
The need of spatial data sharing is increasing with the rapid urban expansion. However, the methods for spatial data
sharing have not been well developed so far. In this paper, we establish a tri-layer geoinformation service framework
using the Grid, SOA and web service. First, we integrated three modes that use geoinformation, which were: 1) the
simple mode of viewing spatial data, 2) the analysis mode of querying and analyzing geoinformation, and 3) the peer
mode of complex computing capabilities. Second, we designed a reasonable, flexible architecture of geoinformation
service according to the three modes and expatiated the principles of each part. Then we argued that the middleware
should be context-sensitive to provide intelligent services. We also discussed how to decide context detailedly and
illustrated the principles of context-sensitive middleware. We found that the service-oriented grid architecture could
realize data sharing and service more smoothly and accessibly.
A scalable key management scheme with minimizing rekey cost for secure multicast over satellite networks
Author(s):
Junwei Gao;
Zongkai Yang;
Haitao Xie
Show Abstract
Satellite networks are playing a more and more important role in network infrastructure. They are useful in providing
broadband connectivity to remote locations which are harder to reach through terrestrial infrastructure. Data
confidentiality and integrity are two critical issues for satellite networks. The multicast traffic should be accessible only
to subscribers, this requires security and efficient methods to generate, distribute and update the keys. Access control can
be achieved by data encryption, such as end to end security mechanisms----IPSec. Due to the high rekeying cost, most
current key management protocols do not scale well for secure multicast over satellite networks. In this article we
proposed a scalable key management scheme to provide secure communication in satellite networks with minimal key
management overhead. The principle of this approach is to break up IPSec encryption into multiple encryption zones on
a single packet and encrypts different regions of the IP packet using different keys. All of those keys are composed into
just only one multi group key tree for secure multicast over satellite networks. The proposed scheme can reduce the
communication and storage overhead significantly. In addition, the proposed key graph is scalable well.
The setting for ground based augmentation system station
Author(s):
Yude Ni;
Ruihua Liu
Show Abstract
Based on the minimum field strength requirement within the whole GBAS service volume, this paper performs nominal
link power budget for GBAS VHF data broadcast (VDB) system, and the required power transmitted from VDB system
is derived. The paper elaborates the requirement of Desired-to-Undesired (D/U) signal ratio for a specific VHF airborne
receiver to ensure the normal operation by the test, and presents the experimental method and results for acquiring the
D/U signal ratios. The minimum geographical separations among GBAS, VOR and ILS stations are calculated according
to the specifications of these three kinds of navigation systems.
Application of M-methods to satellite orbit determination
Author(s):
Xiaogang Pan;
Haiyin Zhou;
Yuanyuan Jiao;
Weinan Jiang
Show Abstract
This paper analyses concretely the theory of M-methods, establishes the model of steady Satellite Orbit Determination
(SOD) based on M-methods, which can farthest restrain gross errors so as to enhance the precision of SOD , and designs
effective iterative algorithm named ameliorative Gauss-Newton method, by researching on the application condition of
M-methods and the practical matter encountered in SOD. Finally the paper carries out simulation experiment to prove
the validity of strategy put forward above. The results of experiment show that the algorithm can strongly improve the
precision of the satellite, and markedly reduce the disadvantageous effect of gross errors. The algorithm can be realized
easily in application to engineering.
A mobile mapping system for spatial information based on DGPS/EGIS
Author(s):
Ling Pei;
Qing Wang;
Juan Gu
Show Abstract
With the rapid developments of mobile device and wireless communication, it brings a new challenge for acquiring the
spatial information. A mobile mapping system based on differential global position system (DGPS) integrated with
embedded geographic information system (EGIS) is designed. A mobile terminal adapts to various GPS differential
environments such as single base mode and network GPS mode like Virtual Reference Station (VRS) and Master-
Auxiliary Concept (MAC) by the mobile communication technology. The spatial information collected through DGPS is
organized in an EGIS running in the embedded device. A set of mobile terminal in real-time DGPS based on GPRS
adopting multithreading technique of serial port in manner of simulating overlapped I/O operating is developed, further
more, the GPS message analysis and checkout based on Strategy Pattern for various receivers are included in the process
of development. A mobile terminal accesses to the GPS network successfully by NTRIP (Networked Transport of
RTCM via Internet Protocol) compliance. Finally, the accuracy and reliability of the mobile mapping system are proved
by a lot of testing in 9 provinces all over the country.
Research on GNSS receiver for spinning projectile in trajectory correction fuze
Author(s):
Hongbing Xiao;
Qiang Shen;
Qing Zhao;
Huquan Li;
Qin Wang
Show Abstract
In trajectory correction fuze of spinning projectiles, the rotating rate experienced by fuze GNSS(Global Navigation
Satellite System) receiver causes it positioning inaccurately for the amplitude or phase of signal from them are
modulated by rotation. With multi-antenna array, this GNSS Receiver could improve signal-to-noise and anti-interference
ability of the system. In addition, the special rotation demodulation loop with three channels helped the
GNSS receiver demodulate rotation-modulated signals and thus provided correct position and attitude information.
Besides, the quick searching and parallel algorithm realization based on SDR and FPGA were given here. At last, the effect of magnitude and phase modulation and roll rates were simulated, and primary data were obtained. The results show that it can capture and track the rotating projectiles effectively.
Construction of mobile digital city based on WiMAX wireless broadband technology
Author(s):
Zhenfeng Shao;
Yuan Yao;
Qimin Cheng;
Xianqiang Zhu
Show Abstract
In this paper, the technical attribute developing from the fixed wireless broadband technology (IEEE802.16-2004) to
mobile wireless broadband technology (IEEE802.16e-2005) is discussed. A mobile WiMAX (Worldwide Interoperability for Microwave Access) network structure is designed for the special needs of mobile digital city. This paper designed and optimized the specific network structure. The function of mobile wireless video, audio, data service
and others, which can manage and service for the mobile digital city are realized based on the mobile WiMAX network.
Urban function district clustering based on GIS and self-organizing feature map network
Author(s):
Yufeng Shi;
Yan Wang;
Junru Cao
Show Abstract
Urban function partitioning is one of the important tasks of urban land utilization and management. The goal of urban
function partitioning is to make the urban land form a set of specific function units and regular spatial structures. Spatial
clustering is the key process of urban function partitioning. Based on geographical information system (GIS) and the
principle of self-organizing feature map network, this paper presents a combined -type of spatial clustering. That is to
say, the attribute features and their spatial positions are processed by a unitive spatial clustering model, and then the
isolated "islands" or the "holes" of spatial clustering outputs should be smoothed into their neighborhood. This method
fully mines the connotative spatial clustering information in spatial attribute data and spatial positions. The experiment
shows that the unitive spatial clustering method can provide a sufficient and reliable basis for urban function partitioning.
Analysis on an acquisition algorithm for weak signal GPS receiver
Author(s):
Cheng Song;
Shaowei Yong;
Feixue Wang
Show Abstract
The weak signal environment puts forward the great challenge to GPS signal acquisition algorithm. In this paper, the
signal model of GPS receiver is established, in which the Doppler compensation is considered. The segment correlation video
integration method using envelope detector is adopted, and this method is optimally designed by deriving the
optimum IF integration time and optimum segment number. In order to avoid the effect of navigation data bit-transition,
the suboptimum IF integration time is also proposed, which performs close to the optimum approach.
QFT/H∞ robust mixed sensitivity control of command tracking system for space vehicle
Author(s):
Changwei Yang;
Jinwen An
Show Abstract
This paper describes a QFT/H∞ design method which combines the Quantitative Feedback Theory (QFT) design concept
and robust H∞ optimal control technique via linear matrix inequality (LMI) convex optimization approach. The
relationship between QFT and H∞ robust control of tracking systems will be discussed. Based on our extensive
experience with both H∞ and QFT design approaches, it appears reasonable that by synthesizing both into a single design
process and enjoying the benefits offered by each approach. The complexity of the robust control system design for
space vehicle is decreased by combined QFT/H∞ design technique. Furthermore the robust controller of command
tracking system is designed by QFT/H∞ method using the advantages of the two methods for space vehicle, and the
results of design are validated through simulations.
Analysis on handover management of mobile IP protocols in satellite networks
Author(s):
Yang Song;
Xuemai Gu
Show Abstract
In this paper, an analysis on mobility approaches suitable for satellite networks handover management is presented. The
paper starting point is the well-known Mobile IP protocol in satellite networks. Although the protocol supports mobility
of mobile nodes in the Internet, it performs poorly when handovers happen while a communication session is active in
satellite networks. Mobile IP extensions, such as Fast Mobile IP (FMIP), Hierarchical Mobile IP (HMIP), and Fast
Hierarchical Mobile IP (FHMIP) which are rarely used in satellite networks have been proposed to handle the drawbacks
of Mobile IP in satellite networks in this paper. How to make these protocols suitable for satellite networks handover is
discussed here. A satellite network structure available for using these protocols is given, under which the simulations is
contributed. The different schemes are compared for the same definitions of structure, bandwidth and time delay. At last,
a conclusion that FHMIP is more suitable for satellite networks communications is drawn.
Performance analysis for LDPC-coded optical PPM communication system in weak turbulence
Author(s):
Hongxing Wang;
Yanqin Su;
Guangyi Zhang;
Tieying Zhang
Show Abstract
Atmosphere Laser Communication (ALC) has the great capability, the better quality of anti-jamming and security, so
ALC is adapt to the military application in particular. But because ALC's channel is atmosphere, ALC will be influenced
by Atmospheric fading and turbulence, which reduce communication reliability. As a result, studying the suitable
modulation and coding becomes the important problems for ALC.
From these, people has put forward plenty of modulation and coding technologies, including On-off keying (OOK),
pulse position modulation (PPM), digital pulse interval modulation (DPIM), dual-header pulse interval modulation(DHPIM)
and so on. Among these, the mean transmit power and error symbol rate of PPM are all less than the others, so
PPM has some applied advantage. People has also studied channel coding technology for PPM in ALC, George Stephen
Mecherle applied RS code to PPM and analyzed error bit performance in 1986, Jon Hamkins and Meera Srinivasan
analyzed the error bit rate of applying Turbo code to PPM through APD detecting in 1998, J. Hamkins analyzed the error
bit performance of 256-ray PPM for Turbo code in 1999, and HU Hongfei analyzed the combined mode and applying
approach of binary LDPC and multi-system PPM. But all of these have not involved the influence of atmosphere weak
turbulence.
The paper introduces LDPC as the channel code to ALC, and combines with PPM, discusses the error performance of
LDPC in weak turbulence, then compares the performance in weak turbulence, Gauss channel and uncoded system. The
emulation results indicate that the LDPC-coded performance of Gauss channel is better than that in weak turbulence
channel, and introducing LDPC can efficiently improve the error performance in Gauss channel and weak turbulence
channel, which has some applied value.
Quantitative evaluation of regional vegetation ecological environment quality by using remotely sensed data over Qingjiang, Hubei
Author(s):
Cheng Wang;
Yan Sun;
Lijun Li;
Qiuwen Zhang
Show Abstract
Vegetation cover is an important component and the best indication to the region ecological environment. The paper
adopts a new method of integrating remote sensing technology and composite index appraisal model based multiple
linear regression for quantitatively evaluating the regional vegetation ecological environment quality(VEEQ). This
method is different to the traditional ecological environment research methods. It fully utilizes the advantages of
quantitatively remote sensing technology, directly extracts the key influencing factors of VEEQ, such as vegetation
indices (RVI, NDVI, ARVI, TMG), humidity indices(NDMI, MI, TMW), soil and landform indices(NDSI, TMB,
GRABS) as the evaluating parameters from data the Landsat 5/TM remotely sensed images, and then puts these factors
mentioned above into the multiple linear regression evaluating model. Ultimately we obtain the VEEQ evaluation rank
figure of the experimental field-part of Qingjiang region. The handy multiple linear regression model, is proved to be
well fit the experimental field for the vegetation ecological environment evaluation research.
Key solutions to WEB-GIS based GPS vehicle monitoring system
Author(s):
Jian Tan;
Liang Gao;
Jian Bing Zhang;
Yingchao Ren;
Lei Wu;
Lei Sheng
Show Abstract
Using Web-GIS to implement GPS monitoring is a promising implementation mode for public service and GPS
monitoring in big organization. The critical bottle neck is the bandwidth, because both geographic maps and vehicle
positioning data in the system are mass and they need to be transmitted frequently. In this paper, we illustrate five
methods to solve this problem. The performances demonstrated in practicing application confirm the validity of these
measures. Finally, the system achieves the balance between computational efficiency and transmission speed on internet
and gains a nice user experience.
Hardware-in-the-loop simulation of the dynamic characteristics of rain fading channel for satellite-to-Earth links at Ka-band
Author(s):
Hongchao Yao;
Huali Wang
Show Abstract
Modeling of rain fading channel dynamics is essential to the real-time prediction of link availability for Ka-band satellite
communication system under rain attenuation impairment, and can validate fade mitigation techniques (FMT) such as
adaptive transmission and diversity. The mechanism of dynamic rain attenuation model based on time-series generator is
firstly concerned in this paper. We further provide a scheme and implementation of real-time simulator for dynamic rain
fading channels based on Hardware-in-the-loop (HIL) simulation method and general Field Programmable Logic Array
(FPGA) device. Finally, the impact of adaptive modulation fade countermeasures (AMFC) in the different state of rain
attenuation is evaluated with simulation results.
An efficient OFDM channel estimation method for satellite and intermediate module repeater channels in DMB system
Author(s):
Min Jia;
Xuemai Gu;
Sebin Im;
Hyungjin Choi
Show Abstract
A noise reduction channel estimation method is needed to improve the performance for digital multimedia broadcasting
(DMB) systems with intermediate module repeater (IMR). It is based on correlation channel estimation method with the
aid of the time-domain received signal and pilot signal. Channel impulse response can be derived by the output of cyclic
correlation directly. Moreover, the information contained in the received signal with the cyclic prefix is made use of in
the proposed method at the receiver. However, the errors caused by the coarse channel impulse response estimation
degrade the performance severely. The noise reduction method is processed by using the time-averaging of channel
impulse responses. The simulation results about the satellite and IMR channels show that the symbol error rate (SER)
performance of the proposed method is much better than other conventional methods.
A geocentric vertical datum for coastal geospatial data infrastructure construction
Author(s):
Shuangxi Wang;
Wenqian Huang;
Di Wu;
Min Liu
Show Abstract
Seamless data for coastal mapping and management is an essential element of coastal spatial data, especially when data
sources have different accuracy, age and quality. Many applications of geospatial data in coastal zone require the
knowledge of the near-shore topography and bathymetry. The coastal mappers are looking for the methods to merge both
topographic and bathymetric data, but the current mismatch in vertical surfaces causes difficulties. In order to obtain
accurate geospatial information for coastal geospatial data infrastructure construction, a more stable reference datum
should be established. This study introduces a seamless geocentric Vertical Datum, and then an ellipsoidal datum is
adopted as vertical reference surface. The reference ellipsoid that is most related to GPS is WGS84 and it is used in this
paper as the stable reference surface. In coastal application area, WGS-84 datum will be selected to manage data
seamlessly. This reference ellipsoidal is chosen as the fundamental vertical reference surface and transformation surface.
The geospatial data cannot be integrated without datum conversion. This paper presents a strategy to seamlessly integrate
geospatial data in coastal areas.
Combined STBC and VBLAST scheme with transmit antenna selection for downlink space distributed MIMO systems
Author(s):
Xi Cao;
Guangxi Zhu;
Gang Su;
Xuejun Liang
Show Abstract
A novel combined space-time block code (STBC) and vertical bell-labs layered space time (VBLAST) scheme is
developed in this paper for the downlinks space distributed multiple-input multiple-output (SD-MIMO) system on spatial
correlated channels. Considering the topological structure of SD-MIMO system and the characteristic of the spatial
correlated SD-MIMO channels, STBC is utilized within each distributed antenna (DA) port while VBLAST is adopted
between largely spaced DA ports. In order to decrease the computational complexity and save the total transmit power, a
transmit antenna selection scheme by the strategy of minimum propagation path loss is investigated as well. The
simulation results prove that the proposed STBC-VBLAST scheme can improve the BER performance obviously
compared with conventional VBLAST scheme and keep the BER performance robust over spatial corrected SD-MIMO
channels. Based on the results of this paper, the proposed STBC-VBLAST scheme appears to be an effective solution to
achieve a good trade off between diversity and multiplexing for downlink SD-MIMO systems.
Analysis and simulations of GDOP in the location of GPS
Author(s):
Zhipeng Wang;
Jun Zhang
Show Abstract
In this paper, the GDOP (Geometric Dilution of Precision) in the location of GPS (Global Positioning System) is studied
from three aspects: First, a new algorithm of GDOP is obtained by matrix factorization. The validity of the new
algorithm is proved by simulation comparing with the old method. Second, the measurement accuracy of stand alone
positioning with weight GDOP matrix becomes better: the 2drm decrease by 0.096m. But, measurement accuracy of
DGPS (Difference GPS) with weight GDOP matrix changes little: the 2drm only decrease by 0.012m. By analyzing the
principle of the DGPS, the conclusion is explained. Third, using a new parameter GDOPi to evaluate each satellite, and
the method could improve the positioning accuracy of DGPS and also will be helpful the surveillance of the satellite
availability.
Spatial uncertain region representation based on cloud model
Author(s):
Zuocheng Wang;
Lixia Xue;
Yunpeng Xiao
Show Abstract
The spatial region in RS image has positional and thematic values uncertainties. Based on the uncertainties and the cloud
theory, the paper studies the representation of spatial uncertain region in image and proposes a new method applied to
spatial uncertain region representation based on cloud model. In 2-dimensional universe of discourse, by the gray and gradient or other digital characters of image, we can construct object-cloud of spatial object. Uncertain spatial region can be represented by object-cloud. Edge of spatial object can be represented by half-cloud-ring. So spatial uncertain region can be represented based on cloud model properly. Experiments testify that the method is both efficient and effective. It enriches the cloud theory, and proposes a new idea for representation of fuzzy object and image comprehending and analyzing, especially remote sensing image.
A novel interference suppression scheme for narrowband interference in satellite communication systems
Author(s):
Heng Liu;
Caijie Xia;
Ronghua Zhou
Show Abstract
Narrowband interference (NBI) is familiar in satellite DS/CDMA systems. Frequency domain notch filter (FDNF) based
on FFT was popular due to its fast arithmetic and absence of convergence time and recursive algorithm. However, at low
jammer-to-signal (JSR), the bit error rate (BER) performance degrades dramatically in comparison with the matched
filter (MF) receiver of the system self. In this paper, a switching metric named compression gain (CG) was introduced to
force FDNF active only after certain interference power level and MF receiver active at lower JSR. By use of CG
switching metric, the algorithm overcomes the threshold effect of traditional FDNF. The advantages of the improved
FDNF (IFDNF) are low computational complexity and expandability due to that the decision of the domain to be used is
made before the interference suppression and the inverse transform. The IFDNF based on CG metric offers better BER
performance than original FDNF at lower JSR, and also outperforms the MF receiver at higher JSR. Numerical
simulation results show the proposed IFDNF overcomes the threshold effect flaw and also verify the validity of the CG
parameter as a switching metric.
A GIS technology based visual simulation for large irrigation district informatization
Author(s):
Bo Yang;
Lijun Li;
Shanzhen Yi
Show Abstract
The technology of Geographic Information System (GIS) and visual simulation applied in large irrigation district
informatization was explored. The paper expatiated on how to combine GIS and visual simulation, visualize and simulate
the spatial and temporal data of distributed interactive simulation system. A spatial information organization approach of
two-dimensional maps and three-dimensional scenes was researched and implemented. Based on this approach, a large
irrigation district management system was introduced.
Indoor positioning performance of Galileo signal
Author(s):
Bo Yang;
Yajun Xu;
Jianjun Luo;
Yong Bao
Show Abstract
Galileo system adopts some new characteristics such as higher transmitting power, new modulation scheme and data-less
pilot tones; from the point of view of signal processing, these new characteristics have advantages for indoor positioning.
After taking into account of these characteristics, the indoor positioning performance of Galileo signal is studied. Indoor
signal processing algorithms, both acquisition and tracking algorithms are given. Galileo signal is modeled and simulated
by Matlab, along with signal processing algorithm. Matlab simulation confirmed the theoretical results obtained by
former investigation and demonstrated Galileo signal's superior performance in indoor positioning.
The compensation methods of wide-band modulator for satellite communication
Author(s):
Jun Yang;
Bo Jiang;
Eryang Zhang
Show Abstract
Aiming at reducing the nonlinear characteristics of the wide-band satellite modulator, a model of the wide-band
modulator is proposed and the dominating reasons leading to distortions are analyzed. Base-band compensation methods
based on this model are provided to minimize the performance degradation. These methods are applied to a 500MHz
wide-band modulator. The result shows the EVM of the modulated constellation is improved from 22.5% to 12.5%.
Modeling and simulation on the non-frequency-selective land mobile satellite channel in shadowing environments
Author(s):
Mingchuan Yang;
Yicheng Jiang;
Qing Guo
Show Abstract
A two-state statistical channel model is proposed for predicting the propagation characteristics of Land Mobile Satellite
Channel (LMSC) according to propagation scattering theory. The underlying channel model takes for granted non-frequency-
selective fading but considers the effects caused by shadowing. For such a statistical channel model, a software simulation model is designed. The simulation model is based on a Random Number Generator (RNG) that generates data sets to compute fading statistics of the propagation channels. Compared with the filter method and the
Rice sum of sinusoids method, the RNG method can be realized precisely in engineering. Furthermore, the operating
frequency band of the simulation model is not restricted to any particular frequency band, for the random numbers used
in the simulation model are independent of frequency. The validity of the statistical model and its corresponding
simulation model is confirmed by comparing fading statistics from the simulation model and a classical analytical model.
The oil and gas engineering techniques based on Digital Earth Platform
Author(s):
Chengming Ye;
Fang Miao;
Xiangsheng Kong;
Xiaojia Bi;
Rui Liu
Show Abstract
The paper mainly discusses the oil and gas engineering techniques based on Digital Earth Platform (DEP), such as
exploration, development, gathering and transportation In the process of using oil and gas resources, Digital Earth
Platform can promote the engineering with the supported by spatial information. It also improves the scientificity,
accuracy, rationality of the oil and gas engineering techniques, greatly reduces cost and increases benefit.
An integrated spatial mutli-objective analysis framework for water allocation in large irrigation districts
Author(s):
Cheng Wang;
Hongmei Ye;
Shanzhen Yi;
Lijun Li
Show Abstract
With the economic development in the irrigation districts, water use conflicts have become more and more urgent,
especially in the arid and semi-arid region. Water allocation of large-scale irrigation is a complex problem which should
be economically efficient and environmentally considerable as well as socially fair, and has received considerable
attention these years. However, these objectives are in conflict with one another in their spatial locations. The integration
of spatial multi-objective analysis with GIS has a good potential in solving the spatial multi-objective problems. In this
study, a spatial framework was formulated to integrate various spatial data and attribute data, based on which, water
allocation model was developed according to the water system's characteristics and finally a user interface was
developed to couple models and GIS.
Research of the small satellite data management system
Author(s):
Xiaozhou Yu;
Fengqi Zhou;
Jun Zhou
Show Abstract
Small satellite is the integration of light weight, small volume and low launch cost. It is a promising approach to realize
the future space mission. A detailed study of the data management system has been carried out, with using new
reconfiguration method based on System On Programmable Chip (SOPC). Compared with common structure of satellite,
the Central Terminal Unit (CTU), the Remote Terminal Unit (RTU) and Serial Data Bus (SDB) of the data management
are all integrated in single chip. Thus the reliability of the satellite is greatly improved. At the same time, the data
management system has powerful performance owing to the modern FPGA processing ability.
A CSCW data mining model for spatial knowledge production
Author(s):
Liang Yu;
Yangge Tian;
Fuling Bian
Show Abstract
This paper proposes a cooperative knowledge production model CSDM (Cooperative Spatial Data Mining), which is
suitable for distributed GIS environment. It aims at two shortages of existing system, the large computational work, and
the dispersive resources in a distributed system. It's based on data-sharing, process synchronization and parallel datamining
method. Although there are many parallel algorithms for data-mining, we choose the GA (Genetic Algorithm) for
illustration. The prototype system shows the model could work effectively in a path selection problem.
Land degradation monitoring using time-series MODIS and TM data
Author(s):
Jinguo Yuan;
Zheng Niu;
Limin Long;
Jingjing Xu
Show Abstract
Land degradation is one of the serious environmental problems that can lead to poverty. North Hebei province is one part
of eco-fragile region in North China, and is a transitional zone from farming to forest and grassland. This paper
evaluated land degradation of North Hebei province from 1987 to 2001. Remote sensing data were time-series MODIS
500m 8-day surface reflectance and 16-day EVI product in 2001 and Landsat TM data in 1987 and 2000. TM and
MODIS data were processed in ERDAS and ModisTool software including projection transformation and subset.
Degradation evaluation indices, including enhanced vegetation index (EVI), land surface water index (LSWI) and
modified soil adjusted vegetation index (MSAVI) of three subregions were calculated. Results showed that the total land
degradation area was 64439km2 in 2001, of which high and severe land degradation level area were 20734km2 and
3948km2, accounting for 32.18% and 6.13%, respectively. Low land degradation level appeared in Yanshan
mountainous area; medium land degradation level mainly appeared in Bashang plateau region, where vegetation types
were cultivated land and grassland, and high land degradation level mainly appeared in Bashang plateau region and the
basin area, where grass land degradation and soil erosion were serious.
A new scheme for improving the TCP transmission efficiency in space network
Author(s):
Yingzhuang Liu;
Chengli He;
Xiaohu Ge;
Yan Dong;
Zili Li
Show Abstract
As the environment of space network is much different from that of terrestrial wired network, the application of TCP
protocol in space network may faces some special challenges, First is that the Round Trip Time (RTT) is greatly
increased by the long propagation on the space radio channel, Second is that the high packets error rate resulting from
space channel cannot be considered negligible, Both these aspects may result in the TCP transmitting efficiency
degradation. A new scheme to enhance the TCP transmitting efficiency is proposed in this paper, simulation results
show that both the throughput and time delay is greatly improved by the use of this scheme.
Using the global positioning system (GPS) to gain three-dimensional dynamic information of bridge pylon
Author(s):
Dongjie Yue;
Zhiqiang Gu;
Chang Xu
Show Abstract
Combining with the actual situation of 300m pylon of Su-tong Bridge, the feasibility that GPS technology is applied in
monitoring of the pylon is analyzed. Starting from the survey principle of GPS technology, the error source and
weakening method is analyzed; the precision of kinematical surveying is estimated. According to the pylon dynamic
characteristic, the key technique and the implementation points are proposed that GPS is applied in gaining
three-dimensional dynamic information of the pylon. Specially, the sampling frequency and the coordinates system is
analyzed in detail. According to the actual test data, the wavelet analysis technology and the spectrum analysis
technology are separately used to research the dynamic movement of the pylon such as long and short periodic change,
the frequency and amplitude of vibration, and the result is compared with the design dynamic performance, they value is
quite coincidence. The experimental analysis indicated that, GPS technology could be used to survey the dynamic characteristic of tall and erect building same as of Cable-Stayed Bridge.
Research and design on the software-based integrated receivers of GPS/Galileo
Author(s):
Z. Lei;
Jiangping Deng;
Jianyu Wang;
Ning Dai
Show Abstract
GPS is already fully operational by America in orbit about the Earth, while the Galileo is not yet operational by E.U.. But
the user receiver equipment should be able to take advantage of both systems to increase accuracy, integrity, and overall
performance with as little impact on each other as possible. This paper presents the research and design on a hybrid
software-based GPS/Galileo receiver, together with the signal acquisition and tracking processing using a GPS/Galileo
software intermediate frequency (IF) architecture.
And the software-based integrated receiver architecture eliminates the traditional baseband ASIC and performs all digital
signal processing in software. This approach completely separates the analog signal conditioning (in hardware) and the
digital signal processing (in software), resulting in significant gain. So it will become increasingly important as new
signals from modernized GPS satellites become available and as the Galileo or China's BeiDou system starts operation.
A data fusion algorithm in GPS/GIS system
Author(s):
Chuan-jun Li;
Qing Wang;
Ying-ying Tai;
Fei Li
Show Abstract
In order to updating GIS database by GPS scientifically, reasonably and esthetically, the data of GPS and GIS must
be fused effectively. A data fusion algorithm based on map matching was presented in this paper. First of all, GPS
error buffer was constructed in the scope of GPS point, the data of GPS and GIS was fused according to the nearest
distance, the most similar direction. The GPS point after fusion was added to GIS database. The topological
relationship was rebuilt and database is updated. The simulated results show the data of GPS/GIS can be fused by
this algorithm and GIS database can be updated in effect.
A new quick algorithm for GPS/Galileo/BD satellite system
Author(s):
Miaoyan Zhang;
Jun Zhang;
Yong Qin
Show Abstract
There will be 70-90 navigation satellites in the sky at the same time when GALILEO and BD reach full operation
capability, and the visible satellite number can reach 30. Then satellite selection will be very important to decrease
computing time for many applications whose processing capability and time are limited such as aviation. The classical
optimal algorithm selects a n-satellite subset from m visible satellites with the minimum GDOP. It requires a long time
for computing especially for much many satellites. This paper proposes a quickly satellite selection algorithm which is
more adaptive when the number of visible satellites is very large. The computer simulation results show that the quickly
satellite selection algorithm has much lower computation load, shortens the computation time greatly than the optimal
algorithm and the increased GDOP is less than 10%.
Quasi-real time estimation of distributed precipitation using EOS/MODIS remote sensing datasets
Author(s):
Qiuwen Zhang;
Cheng Wang;
Fumio Shinohara;
Tatsuo Yamaoka
Show Abstract
The relationships between the atmosphere products of EOS/MODIS and precipitation are analyzed. Some key
meteorological factors tightly related to precipitation are then selected. With the key meteorological factors extracted
from EOS/MODIS remote sensing datasets and the corresponding observed precipitation being the input and output layer
respectively, a Back Propagation(BP) Artificial Neural Network(ANN) is learned and trained. As the test and
application, the distributed precipitations in Qingjiang river basin located at central China are estimated with the
established model. It is concluded that the precipitations estimated by the BP ANN based on EOS/MODIS are nearly
equal to the observed ones at the rainfall stations distributed in the river basin. It is revealed that the integration of
EOS/MODIS and ANN provides a new effective way to estimate the distributed precipitation in river basin near real time.
A navigation computer system based on SINS and GPS
Author(s):
Chengdong Xu;
Xinzhuang Yang;
Huaijian Li;
Li Liu
Show Abstract
This paper provides the detail design of a navigation computer, which is designed specifically for an integrated
SINS/GPS navigation system. According to the function of the navigation computer, the design is described in three
modules: data acquisition module, signal processing module, and communication module respectively. The navigation
computer system selects TMS320VC33 as its CPU and ADS1217 as its A/D convertor. With the powerful Digital Signal
Processor and highly precise A/D convertor, it is demonstrated through experiment that the precision of data acquisition
module is 16 bits, meanwhile, the time used for completing the whole SINS algorithm is less than 1ms.
Situation assessment oriented group decision intelligent support technology
Author(s):
Hao-bin Shi;
Jian-feng Yan;
Zhu-Jun Yu;
Wei-hua Li
Show Abstract
Situation assessment in complex environment is a key technology to develop advanced decision support system. To assess situation precisely in soccer match, the author analyzed the key factors affecting situation of soccer match and put forth a new situation assessment model based on experts' experience and analysis of many cases. In this model, all robots in one soccer team formed a decision group and adoption of group intelligent decision technology enhanced
performance of these robots. The group intelligent decision showed high performance, which is proved in experiments
and many international robot soccer matches.
Precision analysis of passive BD aided pseudolites positioning system
Author(s):
Xiaoming Zhang;
Yan Zhao
Show Abstract
In recent years BD (BeiDou positioning system), an active satellite navigation system, has been widely applied in
geodetic survey, precise engineering survey and GNC (guide, navigation and control system) of weapons because of its
reliability and availability. However, it has several problems on the accuracy, anti-interference and active-positioning. A
passive BD aided pseudolites positioning system is introduced in details in this paper. The configuration and the
operating principle of system are presented. In analyzing the precision of location, one of the crucial aspects to be
studied is how to determine the arrangement of the pseudolites to get the good GDOP, which is discussed in the different
arrangements of the pseudolites in this paper. The simulation results show that the VDOP (vertical dilution of precision)
of BD is improved due to introducing the pseudolites. The experiments indicate the validity of the methods and the
improvement of the positioning precision in the BD aided pseudolite system.
On intermodulation beams of satellite DBF transmitting multibeam array antenna
Author(s):
Hongmei Zhao;
Huali Wang;
Shanxiang Mu
Show Abstract
Digital beamforming (DBF) transmitting multibeam planar array antenna with nonlinear behaviors of solid-state power
amplifiers (SSPA) is discussed. This paper investigates the intermodulation beams produced by the nonlinearity
characteristics of the SSPA with multiple carrier components. The Shimbo model is simplified to describe the nonlinear
behaviors of SSPA. The optimal SSPA input back-off (IBO) point which is given the desired the carrier and the
intermodulatin ratio (C/IM) is simulated. And the tradeoffs between linearity and efficiency of the power amplifier
which influence this IBO is also discussed, helping to selecting suitable SSPA device and reducing the dc power
consumption in satellite array antenna system.
Study on fault-tolerant SINS/GPS integrated navigation system
Author(s):
Long Zhao
Show Abstract
GPS has the advantages of globality and high precision, however its characteristics of low rate of data refreshing and
multipath effect etc. make the GPS fault signal has following three kinds of characteristics: (1) Sometimes there are no
GPS output data. (2) GPS data are outputted, but they are not updated. (3) GPS data are outputted, but they have too
large errors. In order to improve the reliability of the SINS/GPS integrated navigation system, a fault-tolerant scheme is
presented. And four kinds of GPS fault detection algorithms are studied. Fault-tolerant integrated navigation experiment
is simulated with the SINS and GPS data collected practically. The simulation results show that the fault-tolerant
integrated navigation scheme is effective.
Effects and mitigation of multipath on GPS/Galileo
Author(s):
Yi Zhao;
Qing Wang;
Shuguo Pan;
Jun He
Show Abstract
A conventional method to mitigate multipath errors in GNSS receivers is the strobe correlator, which achieves
discriminator function shaping by combining two different narrow-correlator discriminators [1] [2]. The method
performs a good performance when the difference in delays of direct and reflected signal is biggish in GPS scenario.
Nevertheless, the performance of the method is not so good for Galileo scenario. The advent of the European navigation
system Galileo has made it an exigent requirement to develop the receiver that can track Galileo signals as well as GPS
signals. So, a better way should be groped for to mitigate both GPS and Galileo multipath errors. In the paper, a novel
multipath mitigation scheme, named Early-Late Strobe Correlator (ELSC), was presented for both GPS and Galileo
signals. By the Matlab simulation to the method, multipath errors could be mitigated effectively by using ELSC,
especially to Galileo signals. The experiment results show that more excellent performances can be obtained by adopting
ELSC presented in the paper with respected to the strobe correlator, although this will result in a more complex structure
of discriminators.
Implementation of LSCMA adaptive array terminal for mobile satellite communications
Author(s):
Shun Zhou;
Huali Wang;
Zhijun Xu
Show Abstract
This paper considers the application of adaptive array antenna based on the least squares constant modulus algorithm
(LSCMA) for interference rejection in mobile SATCOM terminals. A two-element adaptive array scheme is
implemented with a combination of ADI TS201S DSP chips and Altera Stratix II FPGA device, which makes a
cooperating computation for adaptive beamforming. Its interference suppressing performance is verified via Matlab
simulations. Digital hardware system is implemented to execute the operations of LSCMA beamforming algorithm that
is represented by an algorithm flowchart. The result of simulations and test indicate that this scheme can improve the
anti-jamming performance of terminals.
An extending technique of visualization of the terrain based on LoD of fractal
Author(s):
Guangtang Zhu;
Cheng Wang
Show Abstract
To meet the special requirement in dynamic visualization of the terrain such as excavating and filling, an extending
technique of the terrain visualization based on Fractal LoD (Level of Detail) is proposed. Firstly, a dynamic triangulation
algorithm for the view-dependent and the real-time LoD model of the terrain is present, which is based on the GRID
DEM, constructs the continuous LoD with bintree structure according to the screen error criterion, and the 'crack' is
covered by building the dependent relationships of the different vertexes based on the directed acyclic graph (DAG),
which aim is to render the whole terrain with the static data. Secondly, an extending algorithm based on the fractal is
proposed, which can render more detail part of a special region. At beginning, the fractal dimension is calculated
according the flatness of the regional surface, then 'Diamond-Square' algorithm is disposed to get the extending vertexes
of the deformed region and its transitional regions according the fractal dimension and refinement degree. In order to
solute the problem of the 'crack' and 'T-junction' caused by the discontinuities between the two steps, an extensional
DAG and an extensional bintree structure based on the extensional vertexes are build according a extensional screen
error criterion which is smaller. Lastly, the complete implement method is given.
Frequency estimation algorithm for high dynamic GPS receivers based on UKF
Author(s):
Yunlong Zhu;
Zhongkan Liu;
Qishan Zhang;
Dongkai Yang
Show Abstract
Low estimation precision and high loss-of-lock threshold are the two important drawbacks of the EKF which is widely
used for high dynamic GPS frequency estimate. To resolve the problems of the EKF, a novel algorithm based on
unscented Kalman filter (UKF) is introduced to estimate frequency, and the UKF is simplified according to the linearity
of the state equation, which is the feature of the frequency estimate. The simulations indicate that the loss-of-lock
threshold of the novel algorithm is lower than that of the EKF, the estimation precision is improved compared with that
of the EKF, and the novel algorithm has similar performance as the UKF, but the computational complexity of the novel
algorithm is less than that of the UKF.
Adaptive Kalman filtering methods for tracking GPS signals in high noise/high dynamic environments
Author(s):
Qiyao Zuo;
Hong Yuan;
Baojun Lin
Show Abstract
GPS C/A signal tracking algorithms have been developed based on adaptive Kalman filtering theory. In the research, an
adaptive Kalman filter is used to substitute for standard tracking loop filters. The goal is to improve estimation accuracy
and tracking stabilization in high noise and high dynamic environments. The linear dynamics model and the measurements
model are designed to estimate code phase, carrier phase, Doppler shift, and rate of change of Doppler shift. Two
adaptive algorithms are applied to improve robustness and adaptive faculty of the tracking, one is Sage adaptive filtering
approach and the other is strong tracking method. Both the new algorithms and the conventional tracking loop have been
tested by using simulation data. In the simulation experiment, the highest jerk of the receiver is set to 10G m/s3 with the
lowest C/No 30dBHz. The results indicate that the Kalman filtering algorithms are more robust than the standard tracking
loop, and performance of tracking loop using the algorithms is satisfactory in such extremely adverse circumstances.
Adaptive RED algorithm based on minority game
Author(s):
Jiaolong Wei;
Ling Lei;
Jingjing Qian
Show Abstract
With more and more applications appearing and the technology developing in the Internet, only relying on terminal
system can not satisfy the complicated demand of QoS network. Router mechanisms must be participated into protecting
responsive flows from the non-responsive. Routers mainly use active queue management mechanism (AQM) to avoid
congestion. In the point of interaction between the routers, the paper applies minority game to describe the interaction of
the users and observes the affection on the length of average queue. The parameters α, β of ARED being hard to
confirm, adaptive RED based on minority game can depict the interactions of main body and amend the parameter α, β of ARED to the best. Adaptive RED based on minority game optimizes ARED and realizes the smoothness of
average queue length. At the same time, this paper extends the network simulator plat - NS by adding new elements.
Simulation has been implemented and the results show that new algorithm can reach the anticipative objects.
Design and implementation of high dynamic GNSS digital receiver
Author(s):
Hanmei Li;
Shengqun Geng;
Ce Wang;
Yong Xu;
Qishan Zhang
Show Abstract
The paper presents a scheme of high dynamic GNSS digital receiver using FPGA xc4vsx55 of XILINX and DSP
TMS320VC6701 of TI as core controller. Besides brief introduction of scheme design and hardware structure, the paper
comprehensively introduces design and implementation of algorithms of fast acquisition and tracking of spread spectrum
signal in high dynamic environment. Through optimized design, fast acquisition and tracking of both C code (coarse
ranging code) and P code (precision ranging code) are realized in one chip of FPGA, under the control of DSP.
Employing FFT-based fast acquisition algorithm, acquisition unit realizes the fast acquisition by duplicated using two
FFT/IFFT units with time-sharing fashion, and other optimized FFT calculation structures. Carrier tracking loop is
realized by adopting FLL+PLL method which using FLL tracking carrier Doppler shift with greater bandwidth making
loop closed rapidly and using PLL precisely tracking carrier phase so as to achieve perfect tracking effects. PN code
tracking loop is realized by using multiple non-coherent DLLs with various correlation spacing, which satisfying the
requirements of larger tracking range as well as higher tracking precision by using broad spacing accomplishing initial
tracking and narrow spacing realizing high precision tracking.
Hyperspectral sensing of forests
Author(s):
David G. Goodenough;
Andrew Dyk;
Hao Chen;
Geordie Hobart;
K. Olaf Niemann;
Ash Richardson
Show Abstract
Canada contains 10% of the world's forests covering an area of 418 million hectares. The sustainable management of
these forest resources has become increasingly complex. Hyperspectral remote sensing can provide a wealth of new and
improved information products to resource managers to make more informed decisions. Research in this area has
demonstrated that hyperspectral remote sensing can be used to create more accurate products for forest inventory, forest
health, foliar biochemistry, biomass, and aboveground carbon than are currently available. This paper surveys recent
methods and results in hyperspectral sensing of forests and describes space initiatives for hyperspectral sensing.
Data quality control in eco-environmental monitoring
Author(s):
Chunyan Lu;
Jing Wang
Show Abstract
With the development of science and technology, a number of environmental issues, such as sustainable development,
climate change, environmental pollution, and land degradation become serious. Greater attention has been attached to
environmental protection. The government gradually launched some eco--environmental construction projects. In 1999,
China begin to carry out the project of Grain-for-Green in the west, to improve the eco-environment, and it make some
good effect, but there are some questions that still can not be answered. How about the new grass or forest? Where are
they? How can we do in the future? To answer these questions, the government began to monitor the eco-environment,
based on remote sensing technology. Geography information can be attained timely, but the issue of uncertainty has
become increasingly recognized, and this uncertainty affects the reliability of applications using the data. This article
analyzed the process of eco-environment monitoring, the uncertainty of geography information, and discussed the
methods of data quality control.
The Spot5 span data and multi-spectral data in 2003(2002) were used, combined with land use survey data at the scale of
1:10,000, topography data at the scale of 1:10,000, and the local Grain-for-Green project map. Also the social and
economic data were collected. Eco-environmental monitoring is a process which consists of several steps, such as image
geometric correction, image matching, information extraction, and so on. Based on visual and automated method, land
information turned to grass and forest from cultivated land was obtained by comparing the information form remote
sensing data with the land survey data, and local Grain-for-Green project data, combined with field survey. According to
the process, the uncertainty in the process was analyzed. Positional uncertainty, attribute uncertainty, and thematic
uncertainty was obvious. Positional uncertainty mainly derived from image geometric correction, such as data resource,
the number and spatial distribution of the control points are important resource of uncertainty. Attribution uncertainty
mainly derived from the process of information extraction. Land classification system, artificial error was the main factor
induced uncertainty. Concept defined was not clear, and it reduced thematic uncertainty.
According to the resource of uncertainty, data quality control methods were put forward to improve the data quality. At
first, it is more important to choose appropriate remote sensing data and other basic data. Secondly, the accuracy of
digital orthophoto map should be controlled. Thirdly, it is necessary to check the result data according to relative data
quality criterion to guarantee GIS data quality.
A novel stereo distribution SBR with GEO illuminator
Author(s):
Junli Chen;
Jie Zhu
Show Abstract
The purpose of this paper is to present a system concept for a stereo distribution multistatic SBR using geosynchronous
illumination with various combinations of multistatic reception platforms, such as LEO satellite receivers, UAV
receivers and ground-based receivers (GBR). System operation modes will include airborne and ground moving target
detection and ground mapping functions. For each operation mode, system performance estimation method is
presented.
Improvement of modular multiplication algorithm based on sliding window
Author(s):
Jingdong Chen;
Xiangyan Fang
Show Abstract
The paper makes a conclusion that the key to increase the speed of large number modular multiplication is not only to
decrease the time of addition, but also to decrease the time of circulation shift. According to the analysis of the
principle, implement and time complexity of sliding window algorithm which is more speed, it presents a improving
method about sliding window algorithm to decrease the time of addition and circulation shift by decreasing the judgment
on carry sign and increasing the width of one circulation shift and implements the high speed calculation of modular
multiplication algorithm.
Valuation method study of satellite communication systems based on genetic algorithm
Author(s):
Zhenyu Chen;
Yan Meng;
Jingbo Mao
Show Abstract
This paper analysis some main factors about the construction and the usage in satellite communication systems.
Combining the use of satellite communications resources, a valuation method which helps to improving the utilization
efficiency of satellite communications system is proposed based on the Genetic Algorithm. And the design of evaluation
algorithm and the implement of the system are also given.
Mixed jamming method for SAR
Author(s):
Hong-feng Zhao;
Peng Zhang;
Yong-sheng Wang
Show Abstract
The mixed jamming method of synthetic aperture radar is analyzed and discussed. The methods of active noise and
deception jamming and the signal model of transmitting is described. The raw echo signal of SAR and the model of
jammed echo signal are expatiated, the characteristic of SAR and the evaluating method of jamming effect are
established. Finally, the mixed jamming imaging of SAR is simulated.
