Title :
APC-AB codec modules operating at 16 and 8 kbit/s
Author :
Irie, Kazuki ; Tada, Yasuhiko ; Honma, Kouichi
Author_Institution :
Transmission Syst. Labs., NTT, Kanagawa, Japan
fDate :
2/1/1988 12:00:00 AM
Abstract :
High-quality speech codec modules operating at 16 and 8 kb/s have been developed using an adaptive predictive coding with adaptive bit allocation (APC-AB) scheme. An optimized APC-AB algorithm is studied that reduces processing complexity while maintaining speech quality. The coding algorithm is implemented in two digital signal processors (DSPs). The DSP chips, a framing LSI circuit, a PCM codec, and some peripheral ICs are integrated in each of two compact packages, i.e. codec modules, operating at 16 or 8 kb/s. The codec module size is as small as 80 mm×50 mm×12 mm, and its typical power consumption is 500 mW using 2-μm CMOS LSI technology. At 16 kb/s this APC-AB codec achieves high speech quality, close to that of a 7-bit μ-law PCM. The codec modules are expected to be used for various applications such as customer premises multiplexers for digital leased lines, digital mobile radio, and stored-and-forward-message systems (voice-mail systems)
Keywords :
CMOS integrated circuits; codecs; encoding; large scale integration; pulse-code modulation; speech analysis and processing; vocoders; voice equipment; 12 mm; 16 kbits/s; 2 micron; 50 mm; 500 mW; 8 kbits/s; 80 mm; APC-AB codec modules; CMOS LSI technology; DSP chips; PCM codec; adaptive bit allocation; adaptive predictive coding; coding algorithm; compact packages; customer premises multiplexers; digital leased lines; digital mobile radio; digital signal processors; framing LSI circuit; peripheral ICs; processing complexity; speech codec; speech quality; stored-and-forward-message systems; voice-mail systems; Bit rate; CMOS technology; Digital signal processing chips; Digital signal processors; Large scale integration; Phase change materials; Predictive coding; Signal processing algorithms; Speech codecs; Speech processing;
Journal_Title :
Selected Areas in Communications, IEEE Journal on
