Low‐bit‐rate voice transmission based on transversal block coding

A low‐bit‐rate voice coding scheme, in the range of 10 to 20 KPS, based on predictive transversal block coding is described. This voice coding scheme assumes the use of short‐ and long‐term linear prediction and an optimum PCM/DPCM block companding quantizer which ensures the same dynamic as a standard PCM companded law. It accommodates various data rates by simply modifying the number of bits allocated to the quantizer. Examples based on 8‐kHz sampling rate and data rates of 8 to 16 KBPS are investigated. It is shown that a two‐bit coding scheme at 20 KBPS provides a quality and intelligibility which is quite the same as the standard A‐law 84‐KBPS coding scheme and that with one‐bit coding at 12 KBPS the quality degradation is practically not noticeable in telephony applications. Tape recordings of the investigated cases will be played at the conference.