An Adaptive Pulse Code Modulator for Speech Signals

摘要

The report describes a pulse code modulator for digital coding of speech signals, in which the coding thresholds are not fixed, but vary to follow the envelope variations of the input signal. At the decoder, the levels used to reconstruct the signal are made to vary in the same way. By this means the dynamic range of the system is greatly increased. A speech quality which is adequate for many purposes can be obtained with a transmission rate of 9600 bits/second, using hardware which is simple and cheap. An original analysis of the adaptive operation is presented, together with sujective test results. (Author)