Waveform Coding of 9.6 kb/s Voiceband Data Signals at 32 kb/s.

Various approaches are presented in order to accommodate 9. 6 kb/s modem signals (e.g., V.29) through 32 kb/s ADPCM links. Possible approaches are identified as follows: small changes in the existing algorithm, coding with ADPCM incorporating a 5-bit quantizer instead of 4-bits and filtering before encoding. For each approach, a tradeoff between performance and implementation complexity is outlined.