Split vector quantization using unequal subvectors

摘要

A 1200 b/s vocoder providing a high degree of speech intelligibility and natural voice quality includes a tenth-order linear prediction analyzer, a split vector quantizer for line spectral frequencies, circuitry providing voicing classification and pitch estimation, a differential pitch and gain quantizer and a multiplexer for producing an encoded word transmitted to a receptive demultiplexer. The vocoder provides a characteristic encoded word including a first codeword, a second codeword, a pitch codeword and a gain codeword, wherein the first and second codewords are selected from respective first and second codebooks having a equal number of codewords and wherein the first and second codewords represent unequal numbers of elements of respective first and second sub-vectors. A codebook populating method for a split vector quantizer vocoder is also utilized.