SPEECH CODER FOR PORTABLE COMMUNICATIONS
J. L. Dizon, V.K. Varma · 1989
High quality speech coding schemes for application to digital portable radio communications have received much attention in recent years. This paper presents a real-time single DSP prototype of a 16 kbps sub-band speech coder for much an application. The system architecture, coding algorithm, firmware, and hardware of this coder are addressed. Careful attention has been given to the many special design requirements for interfacing to a Time Division Multiple Acceas (TDMA) radio link. The coder ala0 employs non-linear quantiration of the spectral shape, which results in a substantial improvement in speech quality with negligible added complexity. A single board full-duplex prototype, based on a single Texas Instruments TMS320C25, has been designed and delivers good speech quality.