说明：  脉冲编码调制（PCM）用于在数字传输媒体上传送模拟信号，在PCM中，首先对模拟信号以高于其带宽两倍的奈奎斯特率进行采样，然后对所得样本进行量化。采用不同量化级别生成的PCM编码会影响接收器重建模拟信号的质量。
(Pulse code modulation (PCM) for the media in the digital transmission of analog signal transmission in the PCM, the first analog signal to more than the Nyquist rate of twice the bandwidth sample, and then to quantify the samples. Using different quantization level generated PCM coding receiver will affect the quality of the reconstruction of analog signals.)