APPLICATION OF DELTA MODULATION TO ANALOG-TO-PCM ENCODING

This paper describes a pulse code modulation (PCM) encoder that employs a delta modulator as the analog‐to‐digital converter. A tapped binary shift register and an up‐down counter cause delta modulation signals to be converted to a uniformly quantized PCM format. When tap weights are optimized with respect to a minimum mean square error criterion, the number of shift register stages necessary to obtain a fixed level of output quantizing noise varies inversely with delta modulation sampling rate. Because the tap weights may be rounded to a modest number of binary places, the arithmetic operations are simple to implement. A significant portion of the delta modulation‐to‐PCM converter may be time shared among several signals. © 1969 The Bell System Technical Journal