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Proceedings Paper

Simulation of fog influence on laser beam distribution in atmosphere
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Paper Abstract

Optical fibreless data networks P2P offer fast data transmissions with big transmittance from 1- 10 Gbps on a distance of 1- 6 km. Perfections of such networks are especially flexibility, rapid creation of communications. Sensitivity to atmospheric influences, necessity of light on sight belongs to disadvantages. Transmission through atmosphere be characterized by non-stationarity, inhomogeneity, the influences have random character. It means immediately that it is possible only with difficulty to project conclusions concerning to the measurement on one line upon fiberless line in another position. Contribution tackles a question of forming of the artificial hazy atmospheres, finding the statistical parameters of artificially created foggy atmospheres that could be reproduced to real environment. This work describes created laboratory apparatus powered with fog generator, heat source and ventilating fans, which allow in a controlled way to change the optical transmission inside the bounded space. Laser diode radiation at wavelength of 850 nm is transmitted into created space like this which is scanned with optical power meter after passing of artificially created turbulent vaporous environment. Changes in intensity of the passed lights are captured; the mean value and maximum deviation from the mean value are computed. In this way it is possible to change the reached specific attenuation in dB/km. Owing to turbulences it happens to deviations from the mean value, these abnormalities are characterized by the distribution function that describes the size of turbulences in time. By the help of ergodic theorem then it is possible to deduce that the distribution function of the foggy turbulences gained at continuous time evaluation has same history like the distribution function gained behind the same conditions in the setup in other times. It holds as well that these distribution functions are the same for variety of points in experimental space, provided there are well - kept the same conditions of turbulence creations. Contribution shows the experimental values, shapes of distribution functions, their influence on attenuation of fiberless communication lines and on achieved the transmission BER. At the present time the verification of conclusions is performed from the experimental model on outdoor connecting link working upon the distance of 1,3 km at the transmission rate of 1,25 Gbps.

Paper Details

Date Published: 19 October 2012
PDF: 6 pages
Proc. SPIE 8540, Unmanned/Unattended Sensors and Sensor Networks IX, 85400Y (19 October 2012); doi: 10.1117/12.977617
Show Author Affiliations
Vladimir Vasinek, Technical Univ. of Ostrava (Czech Republic)
Jan Latal, Technical Univ. of Ostrava (Czech Republic)
Petr Koudelka, Technical Univ. of Ostrava (Czech Republic)
Jan Vitasek, Technical Univ. of Ostrava (Czech Republic)
Karel Witas, Technical Univ. of Ostrava (Czech Republic)
Stanislav Hejduk, Technical Univ. of Ostrava (Czech Republic)

Published in SPIE Proceedings Vol. 8540:
Unmanned/Unattended Sensors and Sensor Networks IX
Edward M. Carapezza; Henry J. White, Editor(s)

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