US 5,636,231 AGranted

Method and apparatus for minimal redundancy error detection and correction of voice spectrum parameters

AssigneeMotorola, Inc.

InventorsJian-Cheng Huang, Xiaojun Li, Floyd Simpson

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Abstract

Error detection and correction of a received message, such as a digitized voice message is achieved by generating (318) interpolated vectors for each error vector corresponding to a codebook index in a sequence of codebook indexes representing parameters of portions of the message. A plurality of error corrected candidate vectors for the vector corresponding to the codebook index in error, are generated (322,324,326) by flipping one bit in a sequence of bits representing the codebook index in error. The error corrected candidate vector which has a minimal difference from its corresponding interpolated vector is used (338) to replace the error vector. In the case of digital voice, the vectors are spectral vectors which represent spectral information for a time sample of a voice message. An ordering property of vector components is exploited to detect errors in a received codebook index without parity bits.

Claims22

Dependent claims

A method for detecting and correcting errors in a received digitized voice signal comprising steps of:

(a) storing at least one spectral vector quantization codebook comprising a plurality of spectral vectors and corresponding codebook indexes, the spectral vectors representing spectral information of voice;
(b) receiving a digitized voice signal comprising a sequence of codebook indexes defining corresponding spectral vectors in terms of the at least one spectral vector quantization codebook, each spectral vector representing spectral information of a time frame of a voice message, each codebook index comprising a sequence of bits;
(c) storing the sequence of codebook indexes;
(d) examining the sequence of codebook indexes to determine which codebook indexes and corresponding spectral vectors have an error, and for each codebook index and corresponding spectral vector determined to have an error:
(e) detecting at least one non-error codebook index in the sequence of codebook indexes;
(f) generating an interpolated spectral vector for the spectral vector corresponding to the codebook index determined to have an error based on a spectral vector corresponding to the at least one non-error codebook index;
(g) generating a plurality of error corrected candidate vectors based on the at least one spectral vector quantization codebook for each codebook index and corresponding spectral vector determined to have an error;
(h) comparing each interpolated spectral vector with each of the plurality of error corrected candidate vectors for the corresponding codebook index determined to have an error to determine a measure of difference there between;
and
(i) replacing each codebook index determined to have an error with a codebook index corresponding to an error corrected candidate vector which has a least measure of difference when compared with a corresponding interpolated spectral vector to generate an error corrected sequence of codebook indexes.

7 more elements

A communication device for receiving and correcting errors in a transmitted signal which includes a digitized voice signal, the digitized voice signal comprising a sequence of codebook indexes defining corresponding spectral vectors in terms of the at least one spectral vector quantization codebook, each spectral vector representing spectral information of a time frame of a voice message, each codebook index comprising a sequence of bits, the communication device comprising:

a receiver circuit for receiving the transmitted signal including the digitized voice signal;
a memory coupled to the receiver circuit for storing the sequence of codebook indexes of the digitized voice signal and for storing at least one spectral vector quantization codebook;
a processing unit coupled to the receiver circuit and the memory, the processing unit being programmed for:
(a) examining the sequence of codebook indexes in the memory to determine which codebook indexes and corresponding spectral vectors have an error, and for each codebook index and corresponding spectral vector determined to have an error:
(b) detecting at least one non-error codebook index in the sequence;
(c) generating an interpolated spectral vector for the spectral vector corresponding to the codebook index determined to have an error based on a spectral vector corresponding to the at least one non-error codebook index;
(d) generating a plurality of error corrected candidate vectors based on the at least one spectral vector quantization codebooks for the codebook index determined to have an error;
(e) comparing each interpolated spectral vector with each of the plurality of error corrected candidate vectors for the corresponding spectral vector determined to have an error to determine a measure of difference there between;
(f) replacing each codebook index determined to have an error with a codebook index corresponding to an error corrected candidate vector which has a least measure of difference when compared with a corresponding interpolated spectral vector to generate an error corrected sequence of codebook indexes;
(h) converting the error corrected sequence of codebook indexes to an analog signal representing the voice message;
an audio amplifier coupled to the processing unit for amplifying the analog signal to generate an amplified analog signal;
and
a speaker coupled to the audio amplifier and responsive to the amplified analog signal for emitting as sound the voice message.

10 more elements

A method for communicating a message with minimal error redundancy comprising steps of:

(a) generating a signal for transmission to a communication receiver, the signal including a digital signal comprising a sequence of codebook indexes which define vectors in terms of components of at least one codebook, each vector representing information about a portion of the message;
(b) transmitting the signal to a communication receiver;
(c) storing the at least one codebook in a communication receiver;
(d) receiving the signal at the communication receiver;
(e) storing the sequence of codebook indexes which are included in the signal that is received by the communication receiver;
(f) examining the codebook indexes in the sequence and determining which codebook indexes have errors;
(g) generating an interpolated vector corresponding to each codebook index determined to have an error based on a vector corresponding to a non-error codebook index in the sequence;
(h) generating a plurality of error corrected candidate vectors based on the at least one codebook for each codebook index determined to have an error;
(i) comparing each interpolated vector with the plurality of error corrected candidate vectors to determine a measure of difference there between;
and
(j) replacing each codebook index in the sequence determined to have an error with a codebook index corresponding to an error corrected candidate vector which has a least measure of difference when compared with the interpolated vector to generate an error corrected sequence of codebook indexes.

8 more elements

Dependencies are inferred from the claim text.