Title :
A robust low rate voice codec for wireless communications
Author :
Swaminathan, K. ; Nandkumar, S. ; Bhaskar, U. ; Kowalski, N. ; Patel, S. ; Zakaria, G. ; Li, J. ; Prasad, V.
Author_Institution :
Hughes Network Syst. Inc., Germantown, MD, USA
Abstract :
The design, implementation and performance of a high quality low bit rate speech codec for wireless communication is presented. The codec is based on the CELP model. Generalized analysis-by-synthesis, algebraic fixed codebooks, and multistage LSF techniques are used, resulting in robustness to transmission errors and high quality across changing speech levels and background noise conditions. The bit allocations for the quantization of LSF, pitch and the excitation are chosen in a mode specific manner based on a robust mode classification scheme. A 4.8 kb/s version has been implemented and subjective tests show speech quality that is equivalent to or better than most cellular standard codecs. Performance is also consistent across speech levels and transmission errors
Keywords :
cellular radio; digital signal processing chips; floating point arithmetic; land mobile radio; linear predictive coding; quantisation (signal); spectral analysis; speech codecs; speech intelligibility; speech processing; speech synthesis; CELP model; LSF quantization; Texas Instruments TMS320C30; algebraic fixed codebooks; background noise conditions; bit allocations; cellular standard codecs; floating point DSP; generalized analysis-by-synthesis; high speech quality; multistage LSF techniques; performance; robust low rate voice codec; robust mode classification; speech codec design; speech levels; subjective tests; transmission errors robustness; wireless communication; wireless communications; Background noise; Bit rate; Code standards; Noise robustness; Quantization; Speech analysis; Speech codecs; Speech enhancement; Testing; Wireless communication;
Conference_Titel :
Speech Coding For Telecommunications Proceeding, 1997, 1997 IEEE Workshop on
Conference_Location :
Pocono Manor, PA
Print_ISBN :
0-7803-4073-6
DOI :
10.1109/SCFT.1997.623903
