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Proceedings Paper

Coherent effects and aperture averaging in retroreflected light
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Paper Abstract

An experimental study has been made on the contribution to the effective scintillation index due to two retroreflectors, as a function of retroreflector spacing. For closely spaced retroreflectors the effect of coherent interference at the receiver is seen to increase the effective variance of the received signal, whereas spatial averaging is apparent for more widely spaced retroreflectors. The scintillation index, probability density functions, power spectral densities and fade rates are all affected by the interference. The range, under which these experiments were conducted, was typically 500 - 800m over mixed water/land terrains. The interrogator used a monostatic, 1550nm laser probe beam with a divergence of 0.4 mrad and had a 50mm diameter receiver aperture. Data sets of received power were recorded for durations of 10s each, using a photodiode with a bandwidth of 100kHz. For comparison, the received power from a single retroreflector at various radial positions in the probe beam was recorded. Knowledge of the fade rates and fade durations is of practical importance in considerations regarding the optimal transmission of data packets.

Paper Details

Date Published: 1 September 2006
PDF: 11 pages
Proc. SPIE 6304, Free-Space Laser Communications VI, 63041Y (1 September 2006); doi: 10.1117/12.691317
Show Author Affiliations
Rita Mahon, L-3 Titan Corp. (United States)
William S. Rabinovich, Naval Research Lab. (United States)
Harris R. Burris, Research Support Instruments, Inc. (United States)
Mike S. Ferraro, Sachs Freeman Associates, Inc. (United States)
Wade Freeman, SmartLogic, Inc. (United States)
Christopher Moore, Naval Research Lab. (United States)
James Murphy, Naval Research Lab. (United States)
Michelle Suite, Naval Research Lab. (United States)
Linda Wasiczko, Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 6304:
Free-Space Laser Communications VI
Arun K. Majumdar; Christopher C. Davis, Editor(s)

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