Bi-Rate Voice-Excited Predictive Coder
Original Publication Date: 1985-Nov-01
Included in the Prior Art Database: 2005-Feb-19
Voice-excited predictive coding (VEPC) techniques may conveniently be extended to bi-rate coding by adding a high frequency band to the VEPC original bandwidth and embedding the additional bits into the VEPC bit frame. The voice signal is sampled and coded in A/D (analog-to-digital) using PCM (pulse code modulation) m-law. The digital signal obtained is then BCPCM (block companded pulse code modulation) processed to derive PARCOR coefficients (K) which are used to tune a PREDICTOR providing a residual signal. The residual signal is then conventionally split into several frequency bandwidths. A high frequency band, the energy within which is measured and coded (in HFE (high frequency energy) and Code) and a low frequency band (LPF) processed to provide signal (S) information.