VOICE CODING COMMUNICATION SYSTEM AND DEVICE THEREFOR

Japanese Patent JP3519764

B2

PURPOSE: To prevent degradation of reproduced sound by using the coefficient and gain of a synthetic filter by replacing them by the values corresponding to one vector just before and performing decoding without performing a post filter processing when a flag showing an error does not exist.
CONSTITUTION: The vector (b) that a exciting VQ code book 1 outputs is made into vectors (c) and (f) by the gain adjuster 2 of gain (e) and a synthetic filter 4 and the vectors are outputted to backward gain and synthetic filter adapters 3 and 5. By the gain (d) and the synthetic filter coefficient (g) that the adapters 3 and 5 predict and calculate, gain and synthetic filter coefficient control circuits 8 and 9 control the adjuster 2 and the filter 4. The circuit 9 holds or updates the coefficient (g) based on the error detection flag (k) that a radio line control processor 10 outputs and makes the filter 4 correspond to the next input vector by an output (h). After the vector (f) is processed by a post filter 6 based on the flag (k), the vector (f) is outputted as a PCM output (j) by a PCM conversion circuit 7. Thus, degradation of reproduced sound quality is prevented and an effective error countermeasure is taken.

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JPH11331852	REVERSIBLE CODING METHOD AND REVERSIBLE CODER
JPH09190199	METHOD AND DEVICE FOR EXECUTING VECTOR QUANTIZATION OF VOICE PARAMETER

Sasaki, Seiji

JP30704793A

April 19, 2004

November 15, 1993

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KOKUSAI ELECTRIC CO LTD

G10L19/038; G10L19/005; G10L19/04; H04B14/04; H04B14/06; (IPC1-7): H04B14/04; G10L19/00; G10L19/04; H04B14/06

大塚 学

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