Speech coding and decoding system

Claim 2

A speech coding and decoding system as set forth in claim 1 comprising, at the decoding side an adaptive codebook (1') storing therein a plurality of pitch prediction residual vectors (P); a stochastic codebook (2') storing therein, as white noise, a plurality of code vectors (C); a weighted orthogonalization transforming unit (100) for transforming the optimum code vector (C) from the codebook (2') to a code vector (C') which is orthogonal, after applying a perceptual weighting, to the optimum pitch prediction residual vector (P) from the adaptive codebook (1'); and a linear prediction synthesis filter (200) which receives a vector (X') and reproduces an original speech signal, which vector (X') is to be given as an addition of a code vector (bP) and a vector (gC'), which code vector (bP) is obtained by multiplying the optimum pitch prediction residual vector (P) with an optimum first gain (b) and which vector (gC') is obtained by multiplying the code vector (C') with an optimum second gain (g).

Claim 3

A speech coding and decoding system as set forth in claim 1, wherein said weighted orthogonalization transforming unit (20) comprises: an arithmetic processing means (21) for applying a time-reversing perceptual weighting to the optimum perceptually weighted pitch prediction vector (AP) to calculate the vector inversely in time and generating a time-reversing perceptually weighted arithmetic sub-vector (V), i.e., t AAP; an orthogonalization transformer (22) for receiving each code vector (C) from said stochastic codebook (2) and generating a code vector (C') such that the vector (C') is orthogonal to said arithmetic sub-vector (V); and a perceptual weighting matrix (23) for reproducing the perceptually weighted code vector (AC') by applying a perceptual weighting operation (A) thereof to the orthogonalized code vector (C').

Claim 4

A speech coding and decoding system as set forth in claim 1, wherein said weighted orthogonalization transforming unit (20) comprising: an arithmetic processing means (21) for applying a time-reversing perceptual weighting to the optimum perceptually weighted pitch prediction vector (AP) to calculate the vector inversely in time, and generating a time-reversing perceptually weighted arithmetic sub-vector (V), i.e., t AAP; a Gram-Schmidt orthogonalization transformer (24) for receiving the optimum pitch prediction residual vector (P), the optimum perceptually weighted pitch prediction vector (AP), the arithmetic sub-vector (V) and each code vector (C) from the codebook (2), and producing the code vector (C') therefrom which is orthogonal to said arithmetic sub-vector (V); and a perceptual weighting matrix (23) for reproducing the perceptually weighted code vector (AC') by applying a perceptual weighting operation (A) thereof to the orthogonalized code vector (C').

Claim 5

A speech coding and decoding system as set forth in claim 4, wherein said Gram-Schmidt orthogonalization transformer (24) carries out a calculation process such that said perceptually weighted code vector (AC'), which is orthogonal to said optimum perceptually weighted pitch prediction vector (AP), is generated on the same plane as that on which a perceptually weighted code vector (AC) is defined.

Claim 6

A speech coding and decoding system as set forth in claim 1, wherein said weighted orthogonalization transforming unit (20) comprises: an arithmetic processing means (21) for applying a time-reversing perceptual weighting to the optimum perceptually weighted pitch prediction vector (AP) to calculate the vector inversely in time, and generating a time-reversing perceptually weighted arithmetic sub-vector (V), i.e., t AAP; a householder transformer (25) for receiving said arithmetic sub-vector (V), each code vector (C) of said stochastic codebook (2) and a vector (D) which is orthogonal to all the code vectors of the stochastic codebook (2), and producing a code vector (C') therefrom which is orthogonal to the arithmetic sub-vector (V); and a perceptual weighting matrix (23) for reproducing the perceptually weighted code vector (AC') by applying a perceptual weighting operation (A) thereof to the orthogonalized code vector (C').

Claim 7

A speech coding and decoding system comprising: an adaptive codebook (1) storing therein a plurality of pitch prediction residual vectors (P); a first evaluation unit (10) for selecting, from said adaptive codebook (1), the pitch prediction residual vector which can minimize the power of a pitch prediction error signal vector (AY), which vector (AY) is to be found as an error between a perceptually weighted input speech signal vector (AX) and a pitch prediction reproduced signal (bAP) to be found by perceptually weighting each said pitch prediction residual vector (P) by a matrix (A) and multiplying same with a first gain (b), and further, selecting the corresponding first gain (b); an arithmetic processing means (31) receiving the perceptually weighted input speech signal vector (AX) and applying a time-reversing perceptual weighting to the vector (AX) to calculate the vector inversely in time and generating a time-reversing perceptually weighted input speech signal vector ( t AAX); a sparse-stochastic codebook (2a) storing therein, as white noise, thinned out code vectors (C); an orthogonalization transformer (32) receiving the time-reversing perceptually weighted input speech signal vector ( t AAX) and applying same both a time-reversing perceptually weighting and an orthogonal transforming with respect to the optimum perceptually weighted pitch prediction vector (AP) selected by the first evaluation unit (10), so that a resultant input speech signal vector ( t (AH)AX) is generated, and receiving each said code vector (C) and the optimum pitch prediction vector (AP) and finding an autocorrelation value ( t (AHC)AHC) of a vector (AHC) which is orthogonal to the optimum pitch prediction vector (AP); a means for finding an correlation value ( t (AHC)AX) between said input speech signal vector ( t (AH)AX) given from said orthogonalization transformer (32) and each said code vector (C); and a second evaluation unit (33) for selecting, by using both said autocorrelation value and said correlation value, a code vector (C) which can make minimize a power of an error signal vector between said vector (AX) and said vector (AHC) and can select the corresponding second gain (g), whereby the input speech signal is coded, at a coding side, with information indicating the thus-selected vectors and gains to be sent to a decoding side of the system.