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Proceedings Paper

Interference peak detection based on FPGA for real-time absolute distance ranging with dual-comb lasers
Author(s): Kai Ni; Hao Dong; Qian Zhou; Mingfei Xu; Xinghui Li; Guanhao Wu
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Paper Abstract

Absolute distance measurement using dual femtosecond comb lasers can achieve higher accuracy and faster measurement speed, which makes it more and more attractive. The data processing flow consists of four steps: interference peak detection, fast Fourier transform (FFT), phase fitting and compensation of index of refraction. A realtime data processing system based on Field-Programmable Gate Array (FPGA) for dual-comb ranging has been newly developed. The design and implementation of the interference peak detection algorithm by FPGA and Verilog language is introduced in this paper, which is viewed as the most complicated part and an important guarantee for system precision and reliability. An adaptive sliding window for scanning is used to detect peaks. In the process of detection, the algorithm stores 16 sample data as a detection unit and calculates the average of each unit. The average result is used to determine the vertical center height of the sliding window. The algorithm estimates the noise intensity of each detection unit, and then calculates the average of the noise strength of successive 128 units. The noise average is used to calculate the signal to noise ratio of the current working environment, which is used to adjust the height of the sliding window. This adaptive sliding window helps to eliminate fake peaks caused by noise. The whole design is based on the way of pipeline, which can improves the real-time throughput of the overall peak detection module. Its execution speed is up to 140MHz in the FPGA, and the peak can be detected in 16 clock cycle when it appears.

Paper Details

Date Published: 7 August 2015
PDF: 7 pages
Proc. SPIE 9623, 2015 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems, 96231G (7 August 2015); doi: 10.1117/12.2193746
Show Author Affiliations
Kai Ni, Graduate School at Shenzhen, Tsinghua Univ. (China)
Hao Dong, Graduate School at Shenzhen, Tsinghua Univ. (China)
Qian Zhou, Graduate School at Shenzhen, Tsinghua Univ. (China)
Mingfei Xu, Graduate School at Shenzhen, Tsinghua Univ. (China)
Xinghui Li, Graduate School at Shenzhen, Tsinghua Univ. (China)
Guanhao Wu, Tsinghua Univ. (China)


Published in SPIE Proceedings Vol. 9623:
2015 International Conference on Optical Instruments and Technology: Optoelectronic Measurement Technology and Systems
Jigui Zhu; Hwa-Yaw Tam; Kexin Xu; Hai Xiao; Sen Han, Editor(s)

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