Vector quantization encoder and vector quantization decoder

Claim 1

A vector quantization encoder in a vector quantization device comprising: codebook means for storing a plurality of indexed code vectors and for providing one of the indexed code vectors in response to an code vector index signal, synthesis filters for reproducing speech signals based on the indexed code vector provided by said codebook means, addition means for adding the reproduced speech signals provided by said synthesis filters together to form a reproduced speech signal, error computing means for receiving an input speech signal and for computing a minimum error power valve by determining a difference between the reproduced speech signal and the input speech signal; and evaluating means for selecting the code vector index which minimizes the minimum error power value due to the difference between the reproduced speech signal and the input speech signal to be encoded and for supplying the selected code vector index to said codebook means, wherein: said codebook means includes a plurality of separate codebooks, each stores indexed code vectors for a different frequency band; each of said separate codebooks is provided with one of said synthesis filters; said addition means forms the reproduced speech signal based on which the minimum error power value is to be found; and said evaluating means includes means for selecting indices corresponding to said respective separate codebooks as well as indices for the indexed code vectors of said respective separate codebooks based on the minimum error power value.