A Delta Modulation Filter for Speech-Type Signals

This paper considers the realization of an all-digital system for direct filtering of a delta modulation (DM) encoded signal. We have shown [1] that this system can be realized fairly easily for any type of filter function when the signals are encoded with a linear DM. We now address the problem of digitally filtering an adaptive DM (ADM) encoded signal. We show that we can again realize any type of filter function and our system will operate directly on the ADM bit stream. In addition, we present a circuit realization that does not require complex digital hardware. Performance has been tested via simulation on a digital computer, using a variety of test signals; both temporal and spectral results are presented.