Three kinds of speech encoding schemes, namely, Pulse Code Modulation, A law PCM and Continuous Variable Slope Delta Modulation, are discussed mainly. 主要讨论了三种语音编码方案,即线性脉冲编码调制(PCM,PulseCodeModulation)、A律PCM和连续可变斜率增量调制(CVSD,ContinuousVariableSlopeDeltaModulation)。