| 摘要 |
In a CELP analogue signal coding system, sequences from master codebook 40, which is one dimensional, are filtered in unit 42 and orthogonalised in unit 68 to give codebooks (70, 72) containing even and odd frequency sequences. input analogue signals 20 are filtered in units 34, 36 and orthogonalised in unit 66 to give odd and even frequency sequences. One odd (c<i)<n)) and one even (c<i)<n)) frequency codebook sequence are amplified and compared in units 78, 80 with the filtered and orthogonalised input signals and an optimum pair of sequences and gains are selected. Since odd and even frequency components are orthogonal, sequences are selected from codebooks 70, 72 and compared in units 78, 80 with the filtered incoming analogue signals entirely independently. This effects a reduction in codebook search complexity over a one codebook system. Other means of orthogonalising the codebook, and the incoming sequences, include frequency or time domain divisions. This can be used for speech or video input. <IMAGE>
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