Adaptive Error Correcting Techniques for use in Airborne Satellite Communications Systems.
Final rept. Apr-Dec 75,
ELECTRONIC COMMUNICATIONS INC ST PETERSBURG FLA RESEARCH AND ADVANCED DEVELOPMENT LAB
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Airborne satellite communication systems have been shown to frequently suffer severe degradation of performance due to ionospheric scintillation. This type of interference produces deep fades in received signal power resulting in long error bursts in the demodulated data stream. The objective of this study was to lay the groundwork for a quantitative evaluation of the performance improvement that can be achieved through the use of an adaptive error control technique. Specifically, the adaptive Gallager algorithm and the extended Gallager algorithm were examined to determine which of these provides the better solution ot the error control problem on this channel. The first phase of this study dealt with the heuristic analysis of these two error control techniques on the basis of binary error sequences generated from flight test records of received signal level. Phase I culminates with a recommendation as to which technique should be used. Suggestions regarding the values of important algorithm parameters are also provided. Phase II of this study was devoted to the development of a computer simulation algorithm and the design of a hardware evaluator for the recommended coding technique. The algorithm, used with the AFAL channel simulator, permits the quantitative evaluation of code performance on the simulated scintillation channel.
- Radiofrequency Wave Propagation
- Radio Communications