Waveform Coding of Voiceband Data at 16 kb/s.

The limited ability of medium rate (16 kb/s) speech coders to accommodate voiceband data signals may ultimately limit their application in switched telecommunications networks. The problem of voiceband data compression at 16 kb/s is considered. The performance and attributes of several 16 kb/s compression algorithms (APC, ATC, CELPC, PCM, SBC and VQ) are discussed. Coders which limit the maximum excursion of the quantization error signal such as VQ and PCM are shown to be superior to the more sophisticated speech coders which seek to enhance the perceptual quality of speech by masking the quantization noise with the spectral peaks of the source.