US4924508A
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US
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Pitch detection for use in a predictive speech coder
Assignee: International Business Machines Corp
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Filing: 1988-02-12
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Granted: 1990-05-08
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Expires: 2008-02-12
Abstract
Abstract A pitch detector to adjust long term prediction in a pulse excitation speech coder. A residual signal r(n) is first derived from the speech signal s(n) by short term filtering. Then, r(n) is processed to calculate a prediction error signal e(n) which is subsequently pulse excitation encoded. The processing of e(n) entails prediction of a residual by measuring a pitch related factor M, employing two steps. First calculating a coarse M value through peak clipping and sign transition detection, and then adjusting the M value by autocorrelation--calculations about the roughly spaced peaks.
Inventors
- 👤 Hubert Crepy
- 👤 Philippe Elie
- 👤 Claude Galand
- 👤 Emmanuel Lancon
- 👤 Thierry Liethoudt
- 👤 Michele Rosso
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 21:58
CPC Classifications
G; G10; G10L; G10L19/00; G10L19/04; G10L19/08; G10L25/00; G10L25/90
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
200 words
Method for detecting related data (M) in a representative signal split into blocks of samples including a rough M determination followed by a fine M determination, said method comprising the steps of: a. for said rough M determination: 1. setting a positive threshold (Th + ) and a negative threshold (Th - ) based on characteristics of the representative signal; 2. locating and storing a plurality of samples representative of said blocks of samples, having magnitudes above and below said Th + and Th - ; 3. Identifying significant signal magnitude transitions within said blocks of samples; 4. storing a set of values M' indicative of said samples between each of said significant signal magnitude transitions; and 5. averaging said set of values M' to calculate said rough M determination; and b. for said fine M determination: 1. setting a plurality of autocorrelation zones about said plurality of samples; 2. splitting said blocks of samples into consecutive sub-blocks of samples; 3. autocorrelating, using the autocorrelation zones of a current sub-block of samples; and 4. setting the fine M value equal to a maximum value for said current sub-block of samples in accordance with step 3 of said fine M determination.
Claim 2
Dependent Claim
200 words
Method for detecting related data (M) in a representative signal split into blocks of samples including a rough M determination followed by a fine M determination, said method comprising the steps of: a. for said rough M determination: 1. setting a positive threshold (Th + ) and a negative threshold (Th - ) based on characteristics of the representative signal; 2. locating and storing a plurality of samples representative of said blocks of samples, having magnitudes above and below said Th + and Th - ; 3. Identifying significant signal magnitude transitions within said blocks of samples; 4. storing a set of values M' indicative of said samples between each of said significant signal magnitude transitions; and 5. averaging said set of values M' to calculate said rough M determination; and b. for said fine M determination: 1. setting a plurality of autocorrelation zones about said plurality of samples; 2. splitting said blocks of samples into consecutive sub-blocks of samples; 3. autocorrelating, using the autocorrelation zones of a current sub-block of samples; and 4. setting the fine M value equal to a maximum value for said current sub-block of samples in accordance with step 3 of said fine M determination.
Claim 3
Dependent Claim
69 words
Method for detecting pitch related data (M) in a representative signal, as recited in claim 1, wherein said step of setting a plurality of autocorrelation zones about said plurality of samples includes the steps of: a. locating a maximum value and a predetermined delta variation in each of said plurality of samples to define said autocorrelation zones; and b. filtering said autocorrelation zones to remove any non significant values.
Claim 4
Dependent Claim
49 words
Method for detecting pitch related data (M) in a representative signal, as recited in claim 1, further comprising the step of calculating a residual signal r(n) from said representative signal by a short-term filtering operation using a digital filter to be processed and subsequently quantized into an output signal.
Claim 5
Dependent Claim
63 words
Method for detecting pitch related data (M) in a representative signal, as recited in claim 3, including the steps of: a. tuning a long term prediction filter; b. generating a predicted residual signal; c. subtracting said predicted residual signal from a residual signal r(n); and d. deriving therefrom a prediction error signal e(n) to be coded and subsequently quantized into an output signal.
Claim 6
Dependent Claim
54 words
Method for detecting pitch related data (M) in a representative signal, as recited in claim 4, including the step of encoding a prediction error signal e(n) using regular pulse excitation techniques to convert each sub-block of said predictive error signal e(n) samples into a shorter sequence selected from a set of sequences of samples.
Claim 7
Dependent Claim
37 words
Method for detecting pitch related data (M) in a representative signal, as recited in claim 5, including the step of adjusting said long term prediction filter with a gain factor b based on said fine M value.
Claim 8
Dependent Claim
217 words
Apparatus for detecting pitch related data (M) in a representative signal split into blocks of samples including a rough M determination followed by a fine M determination; comprising: a. for said rough M determination: 1. means for setting a positive threshold (Th + ) and a negative threshold (Th - ) based on characteristics of the representative signal; 2. means for locating and storing a plurality of samples representative of said blocks of samples, having magnitudes above and below said Th + and Th - ; 3. means for identifying significant signal magnitude transitions within said blocks of samples; 4. means for storing a set of values M' indicative of said samples between each of said significant signal magnitude transitions; and 5. means for averaging said set of values M' to calculate said rough M determination; and b. for said fine M determination: 1. means for setting a plurality of autocorrelation zones about said plurality of samples; 2. means for splitting said blocks of samples into consecutive sub-blocks of samples; 3. means for autocorrelating using the autocorrelation zones of a current sub-block of samples; and 4. means for setting the fine M value equal to a maximum value for the current sub-block of samples utilizing the output of the means for autocorrelating a current sub-block of samples.
Claim 9
Dependent Claim
217 words
Apparatus for detecting pitch related data (M) in a representative signal split into blocks of samples including a rough M determination followed by a fine M determination; comprising: a. for said rough M determination: 1. means for setting a positive threshold (Th + ) and a negative threshold (Th - ) based on characteristics of the representative signal; 2. means for locating and storing a plurality of samples representative of said blocks of samples, having magnitudes above and below said Th + and Th - ; 3. means for identifying significant signal magnitude transitions within said blocks of samples; 4. means for storing a set of values M' indicative of said samples between each of said significant signal magnitude transitions; and 5. means for averaging said set of values M' to calculate said rough M determination; and b. for said fine M determination: 1. means for setting a plurality of autocorrelation zones about said plurality of samples; 2. means for splitting said blocks of samples into consecutive sub-blocks of samples; 3. means for autocorrelating using the autocorrelation zones of a current sub-block of samples; and 4. means for setting the fine M value equal to a maximum value for the current sub-block of samples utilizing the output of the means for autocorrelating a current sub-block of samples.
Claim 10
Dependent Claim
70 words
Apparatus for detecting pitch related data (M) in a representative signal, as recited in claim 7, wherein said means for setting a plurality of autocorrelation zones about said plurality of samples includes; a. means for locating a maximum value and a predetermined delta variation in each of said plurality of samples to define said autocorrelation zones; and b. means for filtering said autocorrelation zones to remove any non significant values.
Claim 11
Dependent Claim
48 words
Apparatus for detecting pitch related data (M) in a representative signal, as recited in claim 7, further comprising means for calculating a residual signal r(n) from said representative signal by a short-term filtering operation using a digital filter to be processed and subsequently quantized into an output signal.
Claim 12
Dependent Claim
58 words
Apparatus for detecting pitch related data (M) in a representative signal, as recited in claim 7, including: a. means for tuning a long term prediction filter; b. means for generating a predicted residual signal; c. means for subtracting said predicted residual signal from a residual signal r(n); and d. means for deriving therefrom a prediction error signal e(n).
Claim 13
Dependent Claim
63 words
Apparatus for detecting pitch related data (M) in a representative signal, as recited in claim 7, including means for encoding a prediction error signal e(n) using regular pulse excitation techniques to convert each sub-block of said predictive error signal e(n) samples into a shorter sequence selected from a set of sequences of samples to be processed and subsequently quantized into an output signal.
Claim 14
Dependent Claim
36 words
Apparatus for detecting pitch related data (M) in a representative signal, as recited in claim 7, including means for adjusting said long term prediction filter with a gain factor b based on said fine M value.
References Cited (Backward Citations)
US3573612A
Cited
US3916105A
Cited
US4015088A
Cited
FR2351467A1
Cited
US4516259A
Cited
GB2150377A
Cited
US4757517A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-05-07 | 1993-11-06 | 1994-05-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-05-07 | 1997-11-06 | 1998-05-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-05-07 | 2001-11-06 | 2002-05-08 | $7700.00 | Window Closed / Lapsed |