Real-time implementation of a high quality CELP codec for digital mobile radio system

摘要

The authors describe a real-time implementation of a voiceband codec suitable for the GSM Half-Size Digital Mobile Radio (DMR) system at 900 MHz. This codec exploits the CELP (code excited linear prediction) algorithm running at 6.3 kbit/s in connection with a channel coding scheme, adding 5.1 kbit/s of redundancy to reach the final rate of 11.4 kbit/s for the traffic channel. A comparative evaluation between the full-rate and the half-rate source codecs is presented: the speech quality is almost the same on a wide range of experiments and different speakers.