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Proceedings Paper

Extended Communication Path Length Scintillation Measurements And Model: A Discussion Of Results
Author(s): Robert J. Feldmann
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Paper Abstract

Successful design of an atmospheric laser communications terminal requires an understanding of atmospheric turbulence induced scintillation of the optical signal. Laser beam scintillation is small scale interference within the beam cross section due to turbulence induced fluctuations of the refractive index of the atmosphere, causing variations in the spatial power density at the receiver. The variations in the spatial power density at the receiver manifest themselves as fades and surges of the detected optical signal. By understanding the statistics and power spectrum of the fades and surges, communication terminals can be designed to achieve needed levels of performance by employing optimized choices of increased link margin and error coding. As part of the HAVE LACE (Laser Airborne Communications Experiment) program, amplitude scintillation data was collected and analyzed for extended propagation path lengths. The analysis included the determination of the statistics and temporal power spectrum of the scintillation and the effect on communications performance. Since the HAVE LACE terminals used direct detection of pulsed laser energy, the random variations in the received signal strength was used to evaluate only the atmospheric turbulence induced amplitude scintillations. The collected data has been reduced and compared with a model for extended path length channels. The objective of this comparison was to verify the performance of the model against the collected data. The results from the comparison show a reasonable degree of correlation between the data and the model which warrants further investigation of this approach. This analysis is presented in a form which is consistent with an understanding of the implications of the effect of the communications channel on system performance.

Paper Details

Date Published: 11 October 1989
PDF: 10 pages
Proc. SPIE 1115, Propagation Engineering, (11 October 1989); doi: 10.1117/12.960858
Show Author Affiliations
Robert J. Feldmann, Wright Research and Development Center (United States)

Published in SPIE Proceedings Vol. 1115:
Propagation Engineering
Norman S. Kopeika; Walter B. Miller, Editor(s)

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