Pulse-code modulation - An overview

Pulse-code-modulation (PCM) encoding of digital audio signals has had a long and successful history in the era of the Compact Disc (CD). This brief survey paper argues that it forms the logical way to extend either the bandwidth or the signal-to-noise ratio of a digital audio system, or both, to encompass even higher resolution. Underpinning its operation there are the iron-clad theorems that govern both the sampling-and-reconstruction and the dithered-quantizing processes that lie at its heart. It is adaptable enough to allow fully distortion-free noise shaping to be used if wordlength reduction is necessary, provided that the wordlength is not reduced so far as to cause quantizer overload when using proper dithering.