US5359696A
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Digital speech coder having improved sub-sample resolution long-term predictor
Assignee: Motorola Solutions Inc
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Filing: 1994-03-21
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Granted: 1994-10-25
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Expires: 2014-03-21
Abstract
Abstract A digital speech coder includes a long-term filter (124) having an improved sub-sample resolution long-term predictor (FIG. 5 ) which allows for subsample resolution for the lag parameter L. A frame of N samples of input speech vector s(n) is applied to an adder (510). The output of the adder (510) produces the output vector b(n) for the long term filter (124). The output vector b(n) is fed back to a delayed vector generator block (530) of the long-term predictor. The nominal long-term predictor lag parameter L is also input to the delayed vector generator block (530). The long-term predictor lag parameter L can take on non-integer values, which may be multiples of one half, one third, one fourth or any other rational fraction. The delayed vector generator (530) includes a memory which holds past samples of b(n). In addition, interpolated samples of b(n) are also calculated by the delayed vector generator (530) and stored in its memory, at least one interpolated sample being calculated and stored between each past sample of b(n). The delayed vector generator (530) provides output vector q(n) to the long-term multiplier block (520), which scales the long-term predictor response by the long-term predictor coefficient β. The scaled output βq(n) is then applied to the adder (510) to complete the feedback loop of the recursive filter (124).
Inventors
- 👤 Ira A. Gerson
- 👤 Mark A. Jasiuk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 13:14
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/04; G10L19/08; G10L19/12; G10L2019/0001; G10L2019/0011; G10L2019/0012
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
143 words
A method of reconstructing speech comprising the steps of: receiving from a communication channel a set of speech parameters including codeword I and a delay parameter L, where L may have a value in a predetermined range including integer and non-integer values related to a speech pitch period; generating an excitation vector having a plurality of samples in response to the codeword I; filtering the excitation vector based on at least the delay parameter L and stored filter state samples, the step of filtering comprising the steps of: computing interpolated filter state samples from the stored filtered state samples using a non-integer L to determine the appropriate interpolation parameters, and combining the excitation vector with the interpolated filter state samples, thereby forming a filter output vector having a plurality of filter output samples; and processing the filter output vector to produce reconstructed speech.
Claim 2
Independent Claim
143 words
A method of reconstructing speech comprising the steps of: receiving from a communication channel a set of speech parameters including codeword I and a delay parameter L, where L may have a value in a predetermined range including integer and non-integer values related to a speech pitch period; generating an excitation vector having a plurality of samples in response to the codeword I; filtering the excitation vector based on at least the delay parameter L and stored filter state samples, the step of filtering comprising the steps of: computing interpolated filter state samples from the stored filtered state samples using a non-integer L to determine the appropriate interpolation parameters, and combining the excitation vector with the interpolated filter state samples, thereby forming a filter output vector having a plurality of filter output samples; and processing the filter output vector to produce reconstructed speech.
Claim 3
Dependent Claim
42 words
A method of reconstructing speech in accordance with claim 1 wherein the step of filtering further comprises the step of combining, responsive to L being an integer, the excitation vector with the stored filter state samples, thereby forming filter state output samples.
Claim 4
Dependent Claim
31 words
A method of reconstructing speech in accordance with claim 1 wherein the step of filtering further comprises the step of updating the stored filter state samples using the filter output samples.
Claim 5
Dependent Claim
45 words
A method of reconstructing speech in accordance with claim 1 further comprising the steps of: converting the reconstructed speech to an analog voice signal; and transducing the analog voice signal into a perceptible audio output, such that the speech pitch periods are more accurately predicted.
Claim 6
Dependent Claim
153 words
Apparatus for reconstructing speech comprising: receiving circuitry for receiving from a communication channel a set of speech parameters including codeword I and a delay parameter L, where L may have a value in a predetermined range including integer and non-integer values related to a speech pitch period; generating circuitry for generating an excitation vector having a plurality of samples in response to the codeword I; filtering circuitry for filtering the excitation vector based on at least the delay parameter L and stored filter state samples, the filtering circuitry comprising: computing circuitry for computing interpolated filter state samples from the stored filtered state samples using a non-integer L to determine the appropriate interpolation parameters, and combining circuitry for combining the excitation vector with the interpolated filter state samples, thereby forming a filter output vector having a plurality of filter output samples; and processing circuitry for processing the filter output vector to produce reconstructed speech.
Claim 7
Dependent Claim
153 words
Apparatus for reconstructing speech comprising: receiving circuitry for receiving from a communication channel a set of speech parameters including codeword I and a delay parameter L, where L may have a value in a predetermined range including integer and non-integer values related to a speech pitch period; generating circuitry for generating an excitation vector having a plurality of samples in response to the codeword I; filtering circuitry for filtering the excitation vector based on at least the delay parameter L and stored filter state samples, the filtering circuitry comprising: computing circuitry for computing interpolated filter state samples from the stored filtered state samples using a non-integer L to determine the appropriate interpolation parameters, and combining circuitry for combining the excitation vector with the interpolated filter state samples, thereby forming a filter output vector having a plurality of filter output samples; and processing circuitry for processing the filter output vector to produce reconstructed speech.
Claim 8
Dependent Claim
37 words
Apparatus for reconstructing speech in accordance with claim 5 wherein the combining circuitry further comprises combining, responsive to L being an integer, the excitation vector with the stored filter state samples, thereby forming filter state output samples.
Claim 9
Dependent Claim
29 words
Apparatus for reconstructing speech in accordance with claim 5 wherein the filtering circuitry further comprising updating circuitry for updating the stored filter state samples using the filter output samples.
Claim 10
Dependent Claim
47 words
Apparatus for reconstructing speech in accordance with claim 5 further comprising: converting circuitry for converting the reconstructed speech to an analog voice signal; and transducer circuitry for transducing the analog voice signal into a perceptible audio output, such that the speech pitch periods are more accurately predicted.
Claim 11
Independent Claim
178 words
A method of reconstructing speech comprising the steps of: receiving from a communication channel a set of speech parameters including codeword I and a delay parameter L, where L may have a value in a predetermined range including integer and non-integer value related to a speech pitch period; generating an excitation vector having a plurality of samples in response to the codeword I; filtering the excitation vector based on at least the delay parameter L, a set of stored filter state samples and at least one set of stored interpolated filter state samples, the step of filtering comprises the steps of: choosing a chosen set of filter state samples from the group consisting of the set of stored filter state samples and the at least one set of stored interpolated filter state samples, the step of choosing using at least the delay parameter L, and combining the excitation vector with the chosen filter state samples, thereby forming a filter output vector having a plurality of filter output samples; and processing the filter output vector to produce reconstructed speech.
Claim 12
Independent Claim
178 words
A method of reconstructing speech comprising the steps of: receiving from a communication channel a set of speech parameters including codeword I and a delay parameter L, where L may have a value in a predetermined range including integer and non-integer value related to a speech pitch period; generating an excitation vector having a plurality of samples in response to the codeword I; filtering the excitation vector based on at least the delay parameter L, a set of stored filter state samples and at least one set of stored interpolated filter state samples, the step of filtering comprises the steps of: choosing a chosen set of filter state samples from the group consisting of the set of stored filter state samples and the at least one set of stored interpolated filter state samples, the step of choosing using at least the delay parameter L, and combining the excitation vector with the chosen filter state samples, thereby forming a filter output vector having a plurality of filter output samples; and processing the filter output vector to produce reconstructed speech.
Claim 13
Dependent Claim
45 words
A method of reconstructing speech in accordance with claim 9 further comprising the steps of: converting the reconstructed speech to an analog voice signal; and transducing the analog voice signal into a perceptible audio output, such that the speech pitch periods are more accurately predicted.
Claim 14
Dependent Claim
188 words
Apparatus for reconstructing speech comprising: receiving circuitry for receiving from a communication channel a set of speech parameters including codeword I and a delay parameter L, where L may have a value in a predetermined range including integer and non-integer values related to a speech pitch period; generating circuitry for generating an excitation vector having a plurality of samples in response to the codeword I; filtering circuitry for filtering the excitation vector based on at least the delay parameter L, a set of stored filter state samples and at least one set of stored interpolated filter state samples, the filtering circuitry comprising: choosing circuitry for choosing a chosen set of filter state samples from the group consisting of the set of stored filter state samples and the at least one set of stored interpolated filter state samples, the step of choosing using at least the delay parameter L, and combining circuitry for combining the excitation vector with the chosen filter state samples, thereby forming a filter output vector having a plurality of filter output samples; and processing circuitry for processing the filter output vector to produce reconstructed speech.
Claim 15
Dependent Claim
188 words
Apparatus for reconstructing speech comprising: receiving circuitry for receiving from a communication channel a set of speech parameters including codeword I and a delay parameter L, where L may have a value in a predetermined range including integer and non-integer values related to a speech pitch period; generating circuitry for generating an excitation vector having a plurality of samples in response to the codeword I; filtering circuitry for filtering the excitation vector based on at least the delay parameter L, a set of stored filter state samples and at least one set of stored interpolated filter state samples, the filtering circuitry comprising: choosing circuitry for choosing a chosen set of filter state samples from the group consisting of the set of stored filter state samples and the at least one set of stored interpolated filter state samples, the step of choosing using at least the delay parameter L, and combining circuitry for combining the excitation vector with the chosen filter state samples, thereby forming a filter output vector having a plurality of filter output samples; and processing circuitry for processing the filter output vector to produce reconstructed speech.
Claim 16
Dependent Claim
47 words
Apparatus for reconstructing speech in accordance with claim 11 further comprising: converting circuitry for converting the reconstructed speech to an analog voice signal; and transducing circuitry for transducing the analog voice signal into a perceptible audio output, such that the speech pitch periods are more accurately predicted.
Claim 17
Independent Claim
240 words
A method of encoding speech into sets of speech parameters for transmission on a communication channel, each set of speech parameters, the method comprising the steps of: sampling a voice signal plurality of times to provide a plurality of samples forming a present speech vector; generating a delay parameter L having a value in a predetermine range including integer and non-integer values related to a speech pitch period of the present speech vector; searching excitation vectors to determine a codeword I that best matches the present speech vector, the step of searching comprising the steps of: generating excitation vectors in response to corresponding codewords; filtering each excitation vector comprising the steps of; computing interpolated filter state samples from the stored filtered state samples using a non-integer L to determine the appropriate interpolation parameters, and combining the excitation vector with the interpolated filter state samples, thereby forming a filter output vector having a plurality of filter output samples; processing the filter output vector to produce a reconstructed speech vector; comparing the reconstructed speech vector to the present speech vector to determine the difference therebetween; and selecting the codeword I of the excitation vector for which the reconstructed speech vector differs the least from the present speech vector; and transmitting the selected codeword I and delay parameter L together with preselected speech parameters for the present speech vector on the communications channel, such that the speech pitch periods are more accurately predicted.
Claim 18
Independent Claim
240 words
A method of encoding speech into sets of speech parameters for transmission on a communication channel, each set of speech parameters, the method comprising the steps of: sampling a voice signal plurality of times to provide a plurality of samples forming a present speech vector; generating a delay parameter L having a value in a predetermine range including integer and non-integer values related to a speech pitch period of the present speech vector; searching excitation vectors to determine a codeword I that best matches the present speech vector, the step of searching comprising the steps of: generating excitation vectors in response to corresponding codewords; filtering each excitation vector comprising the steps of; computing interpolated filter state samples from the stored filtered state samples using a non-integer L to determine the appropriate interpolation parameters, and combining the excitation vector with the interpolated filter state samples, thereby forming a filter output vector having a plurality of filter output samples; processing the filter output vector to produce a reconstructed speech vector; comparing the reconstructed speech vector to the present speech vector to determine the difference therebetween; and selecting the codeword I of the excitation vector for which the reconstructed speech vector differs the least from the present speech vector; and transmitting the selected codeword I and delay parameter L together with preselected speech parameters for the present speech vector on the communications channel, such that the speech pitch periods are more accurately predicted.
Claim 19
Dependent Claim
266 words
Apparatus for encoding speech into sets of speech parameters for transmission on a communication channel, each set of speech parameters, the apparatus comprising: sampling circuitry for sampling a voice signal a plurality of times to provide a plurality of samples forming a present speech vector; generating circuitry for generating a delay parameter L having a value in a predetermine range including integer and non-integer values related to a speech pitch period of the present speech vector; searching circuitry for searching excitation vectors to determine a codeword I that best matches the present speech vector, the searching circuitry comprising: generating circuitry for generating excitation vectors in response to corresponding codewords; filtering circuitry for filtering each excitation vector, the filtering circuitry comprising: computing circuitry for computing interpolated filter state samples from the stored filtered state samples using a non-integer L to determine the appropriate interpolation parameters, and combining circuitry for combining the excitation vector with the interpolated filter state samples, thereby forming a filter output vector having a plurality of filter output samples; processing circuitry for processing the filter output vector to produces a reconstructed speech vector; comparing circuitry for comparing the reconstructed speech vector to the present speech vector to determine the difference therebetween; and selecting circuitry for selecting the codeword I of the excitation vector for which the reconstructed speech vector differs the least from the present speech vector; and transmitting circuitry for transmitting the selected codeword I and delay parameter L together with pre-selected speech parameters for the present speech vector on the communications channel, such that the speech pitch periods are more accurately predicted.
Claim 20
Dependent Claim
266 words
Apparatus for encoding speech into sets of speech parameters for transmission on a communication channel, each set of speech parameters, the apparatus comprising: sampling circuitry for sampling a voice signal a plurality of times to provide a plurality of samples forming a present speech vector; generating circuitry for generating a delay parameter L having a value in a predetermine range including integer and non-integer values related to a speech pitch period of the present speech vector; searching circuitry for searching excitation vectors to determine a codeword I that best matches the present speech vector, the searching circuitry comprising: generating circuitry for generating excitation vectors in response to corresponding codewords; filtering circuitry for filtering each excitation vector, the filtering circuitry comprising: computing circuitry for computing interpolated filter state samples from the stored filtered state samples using a non-integer L to determine the appropriate interpolation parameters, and combining circuitry for combining the excitation vector with the interpolated filter state samples, thereby forming a filter output vector having a plurality of filter output samples; processing circuitry for processing the filter output vector to produces a reconstructed speech vector; comparing circuitry for comparing the reconstructed speech vector to the present speech vector to determine the difference therebetween; and selecting circuitry for selecting the codeword I of the excitation vector for which the reconstructed speech vector differs the least from the present speech vector; and transmitting circuitry for transmitting the selected codeword I and delay parameter L together with pre-selected speech parameters for the present speech vector on the communications channel, such that the speech pitch periods are more accurately predicted.
Claim 21
Independent Claim
290 words
A method of encoding speech into sets of speech parameters for transmission on a communication channel, each set of speech parameters, the method comprising the steps of: sampling a voice signal a plurality of times to provide a plurality of samples forming a present speech vector; generating a delay parameter L having a value in a predetermine range including integer and non-integer values relates to a speech pitch period of the present speech vector; searching excitation vectors to determine a codeword I that best matches the present speech vector, the step of searching comprising the steps of: generating excitation vectors in response to corresponding codewords; filtering each excitation vector based on at least the delay parameter L, a set of stored filter state samples and at least one set of stored interpolated filter state samples, the step of filtering comprising: choosing a chosen set of filter state samples from the group consisting of the set of stored filter state samples and the at least one set of stored interpolated filter state samples, the step of choosing using at least the delay parameter L, and combining the excitation vector with the chosen filter state samples, thereby forming a filter output vector having a plurality of filter output samples; processing the filter output vector to produce a reconstructed speech vector; comparing the reconstructed speech vector to the present speech vector to determine the difference therebetween; and selecting the codeword I of the excitation vector for which the reconstructed speech vector differs the least from the present speech vector; and transmitting the selected codeword I and delay parameter L together with preselected speech parameters for the present speech vector on the communications channel, such that the speech pitch periods are more accurately predicted.
Claim 22
Independent Claim
290 words
A method of encoding speech into sets of speech parameters for transmission on a communication channel, each set of speech parameters, the method comprising the steps of: sampling a voice signal a plurality of times to provide a plurality of samples forming a present speech vector; generating a delay parameter L having a value in a predetermine range including integer and non-integer values relates to a speech pitch period of the present speech vector; searching excitation vectors to determine a codeword I that best matches the present speech vector, the step of searching comprising the steps of: generating excitation vectors in response to corresponding codewords; filtering each excitation vector based on at least the delay parameter L, a set of stored filter state samples and at least one set of stored interpolated filter state samples, the step of filtering comprising: choosing a chosen set of filter state samples from the group consisting of the set of stored filter state samples and the at least one set of stored interpolated filter state samples, the step of choosing using at least the delay parameter L, and combining the excitation vector with the chosen filter state samples, thereby forming a filter output vector having a plurality of filter output samples; processing the filter output vector to produce a reconstructed speech vector; comparing the reconstructed speech vector to the present speech vector to determine the difference therebetween; and selecting the codeword I of the excitation vector for which the reconstructed speech vector differs the least from the present speech vector; and transmitting the selected codeword I and delay parameter L together with preselected speech parameters for the present speech vector on the communications channel, such that the speech pitch periods are more accurately predicted.
Claim 23
Dependent Claim
313 words
Apparatus for encoding speech into sets of speech parameter for transmission on a communication channel, each set of speech parameters, the apparatus comprising: sampling circuitry for sampling a voice signal a plurality of times to provide a plurality of samples forming a present speech vector; generating circuitry for generating a delay parameter L having a value in a predetermine range including integer and non-integer values related to a speech pitch period of the present speech vector; searching circuitry for searching excitation vectors to determine a codeword I that best matches the present speech vector, the searching circuitry comprising: generating circuitry for generating excitation vectors in response to corresponding codewords; filtering circuitry for filtering each excitation vector based on at least the delay parameter L, a set of stored filter state samples and at least one set of stored interpolated filter state samples, the filtering circuitry comprising: choosing circuitry for choosing a chosen set of filter state samples from the group consisting of the set of stored filter state samples and the at least one set of stored interpolated filter state samples, the choosing circuitry using at least the delay parameter L, and combining circuitry for combining the excitation vector with the chosen filter state samples, thereby forming a filter output vector having a plurality of filter output samples; processing circuitry for processing the filter output vector to produce a reconstructed speech vector; comparing circuitry for comparing the reconstructed speech vector to the present speech vector to determine the difference therebetween; and selecting circuitry for selecting the codeword I of the excitation vector for which the reconstructed speech vector differs the least from the present speech vector; and transmitting circuitry for transmitting the selected codeword I and delay parameter L together with pre-selected speech parameters for the present speech vector on the communications channel, such that the speech pitch periods are more accurately predicted.
Claim 24
Dependent Claim
313 words
Apparatus for encoding speech into sets of speech parameter for transmission on a communication channel, each set of speech parameters, the apparatus comprising: sampling circuitry for sampling a voice signal a plurality of times to provide a plurality of samples forming a present speech vector; generating circuitry for generating a delay parameter L having a value in a predetermine range including integer and non-integer values related to a speech pitch period of the present speech vector; searching circuitry for searching excitation vectors to determine a codeword I that best matches the present speech vector, the searching circuitry comprising: generating circuitry for generating excitation vectors in response to corresponding codewords; filtering circuitry for filtering each excitation vector based on at least the delay parameter L, a set of stored filter state samples and at least one set of stored interpolated filter state samples, the filtering circuitry comprising: choosing circuitry for choosing a chosen set of filter state samples from the group consisting of the set of stored filter state samples and the at least one set of stored interpolated filter state samples, the choosing circuitry using at least the delay parameter L, and combining circuitry for combining the excitation vector with the chosen filter state samples, thereby forming a filter output vector having a plurality of filter output samples; processing circuitry for processing the filter output vector to produce a reconstructed speech vector; comparing circuitry for comparing the reconstructed speech vector to the present speech vector to determine the difference therebetween; and selecting circuitry for selecting the codeword I of the excitation vector for which the reconstructed speech vector differs the least from the present speech vector; and transmitting circuitry for transmitting the selected codeword I and delay parameter L together with pre-selected speech parameters for the present speech vector on the communications channel, such that the speech pitch periods are more accurately predicted.
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