Differential PCM for Speech and Data Signals

The performance of differential PCM encoders used for both speech and data signals is investigated. Primarily concerned with data signals, this paper shows how differential PCM systems designed for speech perform with differential-phase-modulation, single sideband and partial response data signals operating at data rates of 1200-9600 bits/s. The seven signals considered in this study are shown in Table I. Also discussed are compromise differential PCM systems, which operate well for either speech or data but which are not optimum for either. These results show the advantages and limitations of using differential PCM on switched telecommunication networks carrying speech and data. This paper contains results generated by theoretical studies, computer simulation, and experiments with hardware encoders and modems.