Multimode spectral coding of speech for satellite communications

We present a multimode spectral coding algorithm which employs the enhanced MBE (EMBE) spectral model and a new spectral quantization technique called transformed variable dimension vector quantization (TVDVQ) offering good speech quality at low rate. The EMBE model represents the short-term speech spectrum in a mode-specific way. TVDVQ encodes the variable-dimension spectral components efficiently at low complexity. The resulting 2.9 kb/s source coder offers good speech quality comparable to the 4.8 kb/s CELP 1016 and the 4.15 kb/s IMBE coder. An additional 1.1 kb/s of channel coding preserves the speech quality and intelligibility quite well with up to 2% random bit errors.