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GSM 06.10 Full Rate Vocoder for the TI C6000 DSP

The GSM system of mobile communications typically employs either the Full-Rate, Enhanced Full-Rate or Half-Rate voice compression algorithm to reduce the data rate required to adequately transmit voice-quality speech. The Full-Rate voice coder uses RPE/LTP (residual pulse excitation/long term prediction) coding to compress frames of 160 13-bit samples into 260 bits. The compressed frames are produced every 20 milliseconds, for a data rate of 13,000 bits per second.

I have developed a version of the GSM 06.10 Full Rate Speech vocoder hand-optimized for the Texas Instruments C6000 DSP platform. The algorithm requires just 3.20 Million Cycles per Second (Mcps) to encode and decode one channel of speech (50 20-millisecond frames). The code has been fully tested and is bit-exact with the supplied test vectors. A MATLAB model is also available allowing unprecendented observability of the internal variables to the GSM Full Rate Vocoder.

The TI C6000 family of DSPs is "Optimized for highest performance and ease-of-use in high-level language programming with fixed-point performance from 1200 to 5760 MIPS and floating-point performance from 600 to 1350 MFLOPS." The GSM 06.10 algorithm has been fully tested on a C6713 DSK platform using the ETSI provided test sequences. The code has been developed using the basic instruction set common to the entire C6000 family of processors, allowing the code to be used on any processor in the C6000 family.

With a performance rating of approximately 3.20 Mcps, the GSM 06.10 algorithm will consume just a small fraction of the CPU time per voice channel, allowing the DSP to process multiple voice channels or perform other signal processing functions.
For more information, interested parties may contact me via email at:

David de Gaston

Last Modified: December 02, 2003 at 10:12 EST

ETSI Telecom Standards
Texas Instruments C6000 DSPs
The Mathworks