A Postfiltered DPCM Scheme

Quantization noise constitutes the limiting factor on DPCM performance. For a low number of levels in the quantizer, this noise is also correlated. In this correspondence we present a technique for improving the performance of the DPCM system at a very modest cost. The technique involves the use of an adaptive transversal filter at the receiver output to reduce the effects of quantization noise. The filter is trained at the transmitter and periodic updates sent to the receiver.