An optimised version of CCITT ADPCM and echo canceller for VSAT network

Tremendous interest is currently devoted to the development of VSAT (Very Small Aperture Terminal) network architectures providing voice communications in addition to data. In order to provide good voice communication, an efficient and cost effective voice interface becomes necessary. A DSP implementation often provides a desired solution of realising a low bit rate voice coder and an echo canceller effectively. This paper describes an effective implementation of CCITT G726 voice coder with optimisations (specific to the ISD-16^* VSAT Network) and an echo canceller on a single DSP. Chip TMS320C25. The speech coder is an ADPCM coder and the echo canceller uses NLMS (normalised least mean squared algorithm with block update)