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26 April 1999 Experimental comparison of coherent array detection and conventional coherent detection for laser radar and communications
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There is an upper bound on the effective size of receiving aperture for both the improvement in carrier-to-noise ratio and the reduction in signal fading of a conventional coherent detection system due to the atmospheric turbulence-induced finite transverse coherence length of the received laser field for laser radar and communications. But a coherent array detection system, which uses multiple independent apertures/receivers whose IF's are electro-optically co-phased in real time and then added, can overcome the effective aperture limitation and mitigate the signal fading. This paper presents experimental comparison of the performance of an eight-aperture coherent array detection system and the conventional coherent detection system. The field tests were conducted over two-km range (round-trip). The carrier-to-noise ratio and the fade statistics of the IF signals were investigated for both systems. The results show a gain factor of up to six on the mean carrier-to-noise ratio of the IF signal from the eight-aperture coherent array detection system compared to the conventional coherent detection system even though the two systems collected the same power of laser signal. Also shown is a factor of 100,000 reduction in probability of fade of the IF signal.
© (1999) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Jing Xu, Arnaud Delaval, R. Glenn Sellar, Ammar Al-Habash, Pete Reardon, Ronald L. Phillips, and Larry C. Andrews "Experimental comparison of coherent array detection and conventional coherent detection for laser radar and communications", Proc. SPIE 3615, Free-Space Laser Communication Technologies XI, (26 April 1999);

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