Title :
64 kbit/s audio signal transmission approaches using 32 kbit/s ADPCM channel banks
Author :
Iwadare, Masahiro ; Nishitani, Takao
Author_Institution :
NEC Corp., Kawasaki, Japan
fDate :
2/1/1988 12:00:00 AM
Abstract :
Two simple 64-kb/s wideband coding approaches using 32-kb/s ADPCM (adaptive digital pulse-code modulated) channel banks are proposed and compared to CCITT 64 kb/s ADPCM, which is being recommended as CCITT G.722. These two, folding ADPCM and QMF ADPCM, are intended to pave the way for smooth transition from conventional 4-kHz band telephone systems to 7-kHz wideband systems in private networks. The first approach, supporting the high-quality audio program transmission, requires only samplers and multiplexers at the input and output ports of the channel banks. In the second approach, samplers and multiplexers are replaced by quadrature mirror filters in order to increase coding quality. Performance test results for audio signal transmission show that these simplified approaches provide an inexpensive way to introduce wideband communication systems
Keywords :
encoding; filtering and prediction theory; multiplexing equipment; private telephone exchanges; pulse-code modulation; telephone systems; 32 kbits/s; 4 kHz; 64 kbits/s; 7 kHz; ADPCM channel banks; adaptive digital pulse-code modulated; audio program transmission; audio signal transmission; coding quality; multiplexers; private networks; quadrature mirror filters; samplers; telephone systems; wideband coding; wideband communication systems; Audio coding; Channel bank filters; Circuits; Codecs; Hardware; Mirrors; Multiplexing; Telephony; Testing; Wideband;
Journal_Title :
Selected Areas in Communications, IEEE Journal on
