Development of a 16-kb/s speech codec for telephone applications

This paper describes the development of a new approach to hardware implementation of speech compression algorithms. In considering the hardware architecture much consideration was given to future integration into the public telephone system or other multiuser systems. We propose a multichannel multiprocessor system placed at the central office rather than the traditionally considered single channel DSP-chip system. Dedicated processors and distributed and parallel processing are basic elements in the system architecture. The proposed approach was used to develop an experimental real-time processor for 16-kb/s compression, implementing the adaptive subbands excited transform (ASET) coding algorithm [1]. A system capable of serving up to 24 channels has been successfully built and demonstrated. In addition to high-quality speech, the experimental system results in a cost per channel end that is approximately one-third the cost of a DSP-chip implementation.