Time-Shared Codecs for Multichannel Delta Modulation and Differential PCM

Current practice for multichannel delta modulation (DM) terminals uses one DM codec per channel-end. This paper describes methods by which one high-speed DM codec can be timeshared over a large number of channels. The methods are also applied to multichannel differential PCM (DPCM) terminals. In both cases the time-shared codecs include step-size adaptation determined by the recent past history of the coded digital signal. A method for digital conversions between multichannel linear PCM and adaptive DPCM (ADPCM) formats is also described.