Use of a single chip fixed-point DSP for multiple speech channel vocoders

In this paper, the use of an advanced digital signal processor (DSP) makes possible the parallel real-time implementation of more than one speech coder on a single-chip DSP. Thus, many speech channels can share a single digital communications channel at low cost. Besides the hardware requirements, the algorithms' implementation is considered for multi-channel single-pitch excited LPC vocoders. The Motorola DSP56000/DSP56001 is selected and the execution times are presented. A variable length coding scheme for reduced bit-rate is also described. Up to 10 vocoders are simultaneously implemented on a single DSP and the algorithms can be used as the basis for the implementation of more sophisticated speech coders.