Multistage positive product vector quantization for line spectral frequencies in low rate speech coding

Claim 2

A low bit rate method of communicating an input vector X representing an audible signal through a channel comprising the steps of: a) quantizing the input vector X to determine a scalar scaling factor f and a codevector C; b) looking up codevector C and scaling factor f in a codebook to create an index I c ; c) subtracting the codevector C from the original input vector X to result in an error vector E; d) scaling the error vector E by scaling factor f to result in scaled error vector J; e) selecting a plurality of base vectors J p having all positive components to comprise a base codebook; f) creating a unit sign vector s having the same dimensions as vector J with same signs for each component as J; g) switching the polarity of all negative components of input vector J to create J p ; h) finding an index, I p , of the vector in the base codebook closest to J p ; i) transmitting the index I p , sign vector s, and index I c to a receiver/decoder.

Claim 3

The low bit rate method of communicating of claim 1 further comprising, after the step of transmitting, at a receiver/decoder the steps of: a) receiving a dataset I p ', s', and I c ' at the receiver/decoder being the information transmitted denoting the data set I p , s, and I c , respectively, with added noise due to transmission; b) converting I' c to a codevector C' and a scaling factor f; c) looking up index I p ' in a base codebook having the same vectors as that of the transmitter/encoder, to result in corresponding base vector J' p ; d) adjusting the sign of the base vector J' p by sign vector s' to result in a vector J' being an approximation of vector J; e) inverting scaling factor f' into inverse scaling factor f'; f) multiplying vector J' by received inverse scaling factor f' to result in vector E; g) adding vector E and codevector C' to result in the decoded vector X being substantially similar to an input vector X representing an audible signal provided to a transmitter, and h) repeating steps (a)-(e) for a plurality of datasets resulting in a plurality of decoded vectors X.

Claim 6

A low bit-rate system for communicating an input vector X representing an audible signal comprising: a) a vector quantization (VQ) device which receives the input vector X and determines a scalar scaling factor f and a codevector C; b) an addition device coupled to the VQ device which subtracts the quantized codevector C from the original input vector X to result in an error vector E; c) an I c lookup device having a codebook comprised of a plurality of prestored base vectors C with associated indices, operating to find the closest vector C in base codebook, and its index I c ; d) a multiplication device coupled to addition device and VQ device which scales the error vector E by scaling factor f to result in scaled error vector J; e) a sign vector device coupled to multiplier for receiving vector J and creating a unit vector s having the same dimensions as vector J with same signs for each component as J; f) a sign rectification device coupled to multiplier device for switching the polarity of all negative components of input vector J to create vector J p ; g) a base index lookup device having a base codebook comprised of a plurality of prestored base vectors J p with associated indices, each vector having all positive components, operating to find the closest vector J p to J p in base codebook, and its index I p ; h) a transmitter coupled to the I c lookup device, sign vector device, and base index lookup lookup device for transmitting a plurality of datasets each comprising the look up index I p , sign vector s, and index I c to a receiver/decoder; i) a receiver front end in a decoder/receiver for receiving I p ' and s', and codevector index I c from the transmitter being the dataset transmitted denoting the data sets I p , s, and I c , respectively, with added noise due to transmission; j) a C' lookup device coupled to receiver front end for converting codevector index I c ' into codevector C' and scaling factor f'; k) an inverter coupled to the receiver front end that inverts the scaling factor f' into inverse scaling factor f'; l) a base vector device coupled to the front end operating to look up index I p ' in a prestored base codebook substantially similar to that of base index lookup device in the transmitter to find corresponding base vector J' p ; m) a multiplier coupled to base vector lookup device and front end acting to adjust the sign of the base vector J' p according to sign vector s' to result in a vector J' being an approximation of vector J; n) a scaling device coupled to multiplier and inverter operating to scale vector J' by inverse scaling factor f' to arrive at vector E; and o) an adder coupled to front end and scaling device for combining vector E and received codevector C' into a decoded vector being substantially similar to the input vector X.

Claim 7

A low bit-rate system for communicating an input vector X representing an audible signal comprising: a) a vector quantization (VQ) device which receives the input vector X and determines a scalar scaling factor f and a codevector C; b) an addition device coupled to the VQ device which subtracts the quantized codevector C from the original input vector X to result in an error vector E; c) an I c lookup device having a codebook comprised of a plurality of prestored base vectors C with associated indices, operating to find the closest vector C in base codebook, and its index I c ; d) a multiplication device coupled to addition device and VQ device which scales the error vector E by scaling factor f to result in scaled error vector J; e) a sign vector device coupled to multiplier for receiving vector J and creating a unit vector s having the same dimensions as vector J with same signs for each component as J; f) a sign rectification device coupled to multiplier device for switching the polarity of all negative components of input vector J to create vector J p ; g) a base index lookup device having a base codebook comprised of a plurality of prestored base vectors J p with associated indices, each vector having all positive components, operating to find the closest vector J p to J p in base codebook, and its index I p ; h) a transmitter coupled to the I c lookup device, sign vector device, and base index lookup lookup device for transmitting a plurality of datasets each comprising the look up index I p , sign vector s, and index I c to a receiver/decoder; i) a receiver front end in a decoder/receiver for receiving I p ' and s', and codevector index I c from the transmitter being the dataset transmitted denoting the data sets I p , s, and I c , respectively, with added noise due to transmission; j) a C' lookup device coupled to receiver front end for converting codevector index I c ' into codevector C' and scaling factor f'; k) an inverter coupled to the receiver front end that inverts the scaling factor f' into inverse scaling factor f'; l) a base vector device coupled to the front end operating to look up index I p ' in a prestored base codebook substantially similar to that of base index lookup device in the transmitter to find corresponding base vector J' p ; m) a multiplier coupled to base vector lookup device and front end acting to adjust the sign of the base vector J' p according to sign vector s' to result in a vector J' being an approximation of vector J; n) a scaling device coupled to multiplier and inverter operating to scale vector J' by inverse scaling factor f' to arrive at vector E; and o) an adder coupled to front end and scaling device for combining vector E and received codevector C' into a decoded vector being substantially similar to the input vector X.