TIA/EIA Standard Vocoders

IS-96-A

The algorithm implemented is the TIA/EIA recommendation IS-96-A CDMA, a dynamically variable data rate speech coder. The encoder compresses speech input data in a 16-bit uniform Pulse Code Modulated (PCM) format, at a sample rate of 8kHz to full rate at 9 600, half rate at 4 800, quarter rate at 2 400 and eighth rate at 1 200 bps using the Qualcomm Code Excited Linear Predictive (QCELP) coding technology. The recommendation also uses short-term post-filtering.

At full, half and quarter rates, the 20ms speech frames are processed by a Code Excited Linear Prediction (CELP) encoding process in which the fixed codebook employs a circular recursive codebook structure. At eighth rate, the compression mainly characterises by the energy contour.

This product has been developed and shipped by SIGNALS+SOFTWARE on a number of platforms previously, both standalone and as part of a complete solution, and would be available customized  to meet specific requirements.

For more information please contact our sales team.

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