Design and Evaluation of a Convolutional Codec in Additive White Gaussian Noise, Sinusoidal Interference, and Intersymbol Interference Environment

Abstract

An integrated view of the performance of a rage 3/4, forwardacting, error-correcting convolutional codec, as used on the Intelsat single channel per carrier (SCPC) satellite communication system, is presented with respect to various transmission problems. The available literature does not indicate clearly whether such a codec would have acceptable performance in an environment involving detrimental factors such as sinusoidal interference (SI) or intersymbol interference (ISI). Experimental performance evaluations are given for the cases of an additive white Gaussian noise (AWGN) environment, a pure sinusoidal interference signal, AWGN combined with SI, and finally for AWGN in an ISI environment. The results confirm that this type of codec is designed to combat random errors effectively, and not burst-type errors such as those generated by SL Further observations indicate that it is preferable to measure a codec performance in terms of bit error rate (BER) reduction for a given signal-to-noise (S/N) ratio rather than SIN reduction for a given BER since this latter method is too susceptible to the operating conditions to which the codec is submitted.