Replacing Unencoded PCM/PSK with Convolutional Encoded PCM/PSK

Abstract

Rate 1/2 constraint length 7 convolutionally encoded PCM/QPSK techniques offer significant Bit Error Probability versus Signal to Noise Performance improvements compared to unencoded PCM/BPSK and yet require no increase in system bandwidth and little increase in hardware cost. This applications oriented paper explains the effects on those factors which determine realistic coded modem degradation e.g.: PSK carrier and PCM bit synchronization, phase ambiguity, and coding gain in the presence of noise, jitter, transition density, and offset and gain variations. Measured performance is presented, and pitfalls are identified which can lead to misinterpretation of empirical data.