Institute for Telecommunication Sciences
the research laboratory of the National Telecommunications and Information Administration

S. Voran

Abstract: We describe a 2-channel multiple-description speech coder based on the ITU-T Recommendation G.711 PCM speech coder. The new coder operates in the PCM code domain in order to exploit the companding gain of PCM. It applies a pair of 2-dimensional structured vector quantizers to each pair of PCM codes, thus exploiting the correlation between adjacent speech samples. If both quantizer outputs are received, they are combined to generate an approximation to the original pair of PCM codes. If only one quantizer output is received, a coarser approximation is still possible. When using 6 bits/sample/channel (for a total data rate of 96 kbps) the coder provides an equivalent PCM speech quality of 7.3 bits/sample when both channels are working and 6.4 bits/sample when one channel is working.

Keywords: fading; quantization; speech coding; decoding; Internet telephony; Phase change materials; propagation loss; Communication channels; pulse modulation; speech enhancement


To request a reprint of this report, contact:

Lilli Segre, Publications Officer
Institute for Telecommunication Sciences
(303) 497-3572
LSegre@ntia.gov

For technical information concerning this report, contact:

Stephen D. Voran
Institute for Telecommunication Sciences
(303) 497-3839
svoran@ntia.doc.gov


Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

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