Nonadaptive DPCM Transmission of Monochrome Pictures Over Noisy Communication Channels

The present study is a sequel to the authors´ 1972 paper [1] where the output signal-to-noise ratio SNRois obtained for nonadaptive differential pulse-code modulation (DPCM) systems with an arbitrary linear predictor operating on noisy digital channels. Important stability constraints for an arbitrary linear predictor are obtained. A complete analytical study of previous line-line-and-sample feedback systems is presented. The SNRoimprovement over previoussample feedback is found to increase from approximately 2.6 dB for error-free channels to 4.1 dB for noisy channels. Optimization of the predictor for noisy channel usage is shown to greatly reduce the sensitivity of SNRoto variations in message and channel parameters, while use of the resulting predictor on error-free channels yields SNRovalues which are almost as good as those obtained when the predictor is optimized for error-free channels. Reduction of the effects of digital channel errors on SNRousing various methods, including periodic or pseudorandom resetting are considered briefly. Hardcopy results from computer-simulated DPCM monochrome image transmission systems corroborate our analytical results.