Two approaches for waveform coding of 9.6 kbit/s voiceband data signals through 32 kbit/s ADPCM

摘要

Two approaches are presented for accommodating 9.6 kb/s modem signals (e.g. V.29) through 32 kb/s ADPCM (adaptive digital pulse-code modulation) links. These are small changes in the existing algorithm and coding with ADPCM incorporating a 5-bit, rather than 4-bit quantizer. For each approach, tradeoffs between performance and implementation complexity are described.