US4230906A
Expired / Lapsed
US
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Speech digitizer
Assignee: Time and Space Processing Inc
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Filing: 1978-05-25
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Granted: 1980-10-28
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Expires: 1998-05-25
Abstract
Abstract A speech digitizer is disclosed including an analyzer for generating power and filter coefficient parameters representative of an analog speech waveform. The digitizer also includes a pitch detector for generating a digital pitch parameter substantially representing the fundamental periodicity of the waveform and including range restrictor means for restricting the pitch signal to a range of pitches within a predetermined tolerance if the average pitch of the periodicity signal is below a predetermined level. The pitch detector also includes means for determining the number of extreme maximum and minimum points within a predetermined range of an absolute magnitude difference function thereby generating a structure number signal representing a voiced event. The digitizer includes a voicing detector for generating a three-level voicing/unvoicing parameter representing whether the speech waveform is voiced or unvoiced.
Inventors
- 👤 Charles R. Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 20:37
CPC Classifications
G; G10; G10L; G10L19/00; G10L25/00; G10L25/90
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
557 words
In a digital communication system operating in a multiframe format, a speech digitizer comprising: analyzer means connected to receive an analog speech waveform, said analyzer means including power and filter coefficient means responsive to said waveform for generating in digital format variable filter coefficient and power paramaters representative of said waveform, pitch detector means responsive to said waveform for generating a digital pitch parameter substantially representing the fundamental periodicity of said waveform, said pitch detector means including automatic gain control means for stabilizing said speech waveform, converter means for converting said analog waveform to a digital format in a predetermined time frame, means for generating a digital signal representing an absolute magnitude difference function, said digital signal having a predetermined number of samples representing the variations in the pitch of said analog waveform and having a pattern of recurring maximum and minimum points over the frequency spectra, means for generating a first pitch signal representing the fundamental pitch of said sampled signal, periodicity means for generating a periodicity signal representing the ratio of one of said minimum and one of said maximum points, multiple check means connected to receive said digital signal and said first pitch signal for generating a second pitch signal when one of said multiple signals is lower than the first pitch signal by interpolating over successive ones of said samples to generate said second pitch signal, range restrictor means connected to receive said digital signal, said periodicity signal and said second pitch signal for restricting the range of said pitch signal to a range of pitches within a predetermined tolerance if the average pitch of said periodicity signal is below a predetermined level whereby a third pitch signal is generated representing the best estimate within the restricted range, and means for determining the number of extreme maximum and minimum points within a predetermined range of said absolute magnitude difference function thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number, voice detector means responsive to said waveform for generating a digital voicing parameter representing whether said speech waveform is voiced or unvoiced, multiplexer means for multiplexing said parameters into a digital serial data stream in said multiframe format where selected ones of the frames in said multiframe format occur as a synchronization frame, synchronization means for providing a digital synchronization code whereby said multiplexer multiplexes said synchronization code into a portion of said synchronization frame, first signaling interface means for connecting signaling information to another portion of said synchronization frame, means for transmitting said digital serial stream, synthesizer means connected to receive said digital serial stream for generating a second analog waveform representative of said first analog waveform, said synthesizer means including demultiplexer means for demultiplexing the transmitted parameters, the synchronization code, and the signaling information, second signaling interface means connected to receive the demultiplexed transmitted signaling information, periodic generator means for generating a digital periodic component signal representative of a pitch pulse signal and aperiodic generator means for generating a digital aperiodic signal representative of a random noise signal, mixer means connected to receive said component signals for mixing said component signals thereby forming a driving function signal, and filter means connected to receive said driving function signal for generating said second analog signal thereby representing said first analog signal.
Claim 2
Dependent Claim
557 words
In a digital communication system operating in a multiframe format, a speech digitizer comprising: analyzer means connected to receive an analog speech waveform, said analyzer means including power and filter coefficient means responsive to said waveform for generating in digital format variable filter coefficient and power paramaters representative of said waveform, pitch detector means responsive to said waveform for generating a digital pitch parameter substantially representing the fundamental periodicity of said waveform, said pitch detector means including automatic gain control means for stabilizing said speech waveform, converter means for converting said analog waveform to a digital format in a predetermined time frame, means for generating a digital signal representing an absolute magnitude difference function, said digital signal having a predetermined number of samples representing the variations in the pitch of said analog waveform and having a pattern of recurring maximum and minimum points over the frequency spectra, means for generating a first pitch signal representing the fundamental pitch of said sampled signal, periodicity means for generating a periodicity signal representing the ratio of one of said minimum and one of said maximum points, multiple check means connected to receive said digital signal and said first pitch signal for generating a second pitch signal when one of said multiple signals is lower than the first pitch signal by interpolating over successive ones of said samples to generate said second pitch signal, range restrictor means connected to receive said digital signal, said periodicity signal and said second pitch signal for restricting the range of said pitch signal to a range of pitches within a predetermined tolerance if the average pitch of said periodicity signal is below a predetermined level whereby a third pitch signal is generated representing the best estimate within the restricted range, and means for determining the number of extreme maximum and minimum points within a predetermined range of said absolute magnitude difference function thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number, voice detector means responsive to said waveform for generating a digital voicing parameter representing whether said speech waveform is voiced or unvoiced, multiplexer means for multiplexing said parameters into a digital serial data stream in said multiframe format where selected ones of the frames in said multiframe format occur as a synchronization frame, synchronization means for providing a digital synchronization code whereby said multiplexer multiplexes said synchronization code into a portion of said synchronization frame, first signaling interface means for connecting signaling information to another portion of said synchronization frame, means for transmitting said digital serial stream, synthesizer means connected to receive said digital serial stream for generating a second analog waveform representative of said first analog waveform, said synthesizer means including demultiplexer means for demultiplexing the transmitted parameters, the synchronization code, and the signaling information, second signaling interface means connected to receive the demultiplexed transmitted signaling information, periodic generator means for generating a digital periodic component signal representative of a pitch pulse signal and aperiodic generator means for generating a digital aperiodic signal representative of a random noise signal, mixer means connected to receive said component signals for mixing said component signals thereby forming a driving function signal, and filter means connected to receive said driving function signal for generating said second analog signal thereby representing said first analog signal.
Claim 3
Dependent Claim
207 words
A digitizer as in claim 1 wherein said voice detector means includes: low pass detection and integration means for generating a low pass integrated signal representing the energy in a low frequency band of said waveform, high pass detection and integration means for generating a high pass integrated signal representing the energy in a high pass band of said waveform, first comparator means for generating a voicing function signal when the ratio of said low pass signal to said high pass signal exceeds a first predetermined threshold, second comparator means for generating a strong voicing function signal only when the ratio of said low pass signal to said high pass signal exceeds a second predetermined threshold, and for generating a weak voicing signal when said ratio is less than said second predetermined threshold, third comparator means for comparing said low pass integrated signal with a filtered noise level signal of said low pass integrated signal representing background noise thereby forming a power present signal when said low pass integrated signal exceeds said noise level signal, and decision logic means for generating said voicing parameter in response to said strong voice signal, to said structure signal, to said periodicity signal, or to said weak voice and periodicity signal.
Claim 4
Dependent Claim
533 words
In a digital communication system operating in a multiframe format, a speech digitizer comprising: analyzer means connected to receive an analog speech waveform, said analyzer means including power and filter coefficient means responsive to said waveform for generating in digital format variable filter coefficient and power parameters representative of said waveform, pitch detector means responsive to said waveform for generating a digital pitch parameter substantially representing the fundamental periodicity of said waveform, said pitch detector means including; automatic gain control means for stabilizing said waveform, converter means for converting said analog waveform into a digital format in a predetermined time frame, function means for generating a digital signal representing an absolute magnitude difference function, said digital signal having a predetermined number of samples representing the variations in the pitch of said analog waveform and having a pattern of recurring maximum and minimum points over the pitch range, means for generating a first digital pitch signal representing the fundamental pitch of said waveform, periodicity means for generating a periodicity signal representing the ratio of one of said minimum and one of said maximum points, multiple check means connected to receive said digital signal and said first pitch signal for generating a second pitch signal when one of said multiple signals is lower than said first pitch signal by interpolating over successive ones of said samples to generate said second pitch signal, and range restrictor means connected to receive said digital signal, said periodicity signal, and said second pitch signal for restricting the range of said pitch signal to a range of pitches within a predetermined tolerance if the average pitch of said periodicity signal is below a predetermined level whereby a third pitch signal is generated representing the best estimate within the restricted range, voice detector means responsive to said waveform for generating a digital voicing parameter representing whether said speech waveform is voiced or unvoiced, multiplexer means for multiplexing said parameters into a digital serial data stream in said multiframe format where selected ones of the frames in said multiframe format occur as a synchronization frame, synchronization means for providing a digital synchronization code whereby said multiplexer multiplexes said synchronization code into a portion of said synchronization frame, first signaling interface means for connecting signaling information to another portion of said synchronization frame, means for transmitting said digital serial stream where said serial stream includes during said synchronization frame said synchronization code in one portion and said signaling information in said other portion, synthesizer means connected to receive said digital stream for generating a second analog waveform representative of said analog waveform, said synthesizer means including demultiplexer means for demultiplexing the transmitted parameters, the synchronization code, and the signaling information, second signaling interface means connected to receive the demultiplexed transmitted signaling information, periodic generator means for generating a periodic component signal representative of a pitch pulse signal and aperiodic generator means for generating an aperiodic signal representative of a random noise signal, mixer means connected to receive said component signals for mixing said component signals thereby forming a driving function signal, and filter means connected to receive said driving function signal for generating said second analog waveform thereby representing said first analog waveform.
Claim 5
Dependent Claim
533 words
In a digital communication system operating in a multiframe format, a speech digitizer comprising: analyzer means connected to receive an analog speech waveform, said analyzer means including power and filter coefficient means responsive to said waveform for generating in digital format variable filter coefficient and power parameters representative of said waveform, pitch detector means responsive to said waveform for generating a digital pitch parameter substantially representing the fundamental periodicity of said waveform, said pitch detector means including; automatic gain control means for stabilizing said waveform, converter means for converting said analog waveform into a digital format in a predetermined time frame, function means for generating a digital signal representing an absolute magnitude difference function, said digital signal having a predetermined number of samples representing the variations in the pitch of said analog waveform and having a pattern of recurring maximum and minimum points over the pitch range, means for generating a first digital pitch signal representing the fundamental pitch of said waveform, periodicity means for generating a periodicity signal representing the ratio of one of said minimum and one of said maximum points, multiple check means connected to receive said digital signal and said first pitch signal for generating a second pitch signal when one of said multiple signals is lower than said first pitch signal by interpolating over successive ones of said samples to generate said second pitch signal, and range restrictor means connected to receive said digital signal, said periodicity signal, and said second pitch signal for restricting the range of said pitch signal to a range of pitches within a predetermined tolerance if the average pitch of said periodicity signal is below a predetermined level whereby a third pitch signal is generated representing the best estimate within the restricted range, voice detector means responsive to said waveform for generating a digital voicing parameter representing whether said speech waveform is voiced or unvoiced, multiplexer means for multiplexing said parameters into a digital serial data stream in said multiframe format where selected ones of the frames in said multiframe format occur as a synchronization frame, synchronization means for providing a digital synchronization code whereby said multiplexer multiplexes said synchronization code into a portion of said synchronization frame, first signaling interface means for connecting signaling information to another portion of said synchronization frame, means for transmitting said digital serial stream where said serial stream includes during said synchronization frame said synchronization code in one portion and said signaling information in said other portion, synthesizer means connected to receive said digital stream for generating a second analog waveform representative of said analog waveform, said synthesizer means including demultiplexer means for demultiplexing the transmitted parameters, the synchronization code, and the signaling information, second signaling interface means connected to receive the demultiplexed transmitted signaling information, periodic generator means for generating a periodic component signal representative of a pitch pulse signal and aperiodic generator means for generating an aperiodic signal representative of a random noise signal, mixer means connected to receive said component signals for mixing said component signals thereby forming a driving function signal, and filter means connected to receive said driving function signal for generating said second analog waveform thereby representing said first analog waveform.
Claim 6
Dependent Claim
51 words
A digitizer as in claim 3 further including means for determining the number of extreme maximum and minimum points within a predetermined range of said absolute magnitude difference function thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number.
Claim 7
Dependent Claim
138 words
A digitizer as in claim 3 wherein said voice detector means includes: low pass detection and integration means for generating a low pass integrated signal representing the energy in a low frequency band of said speech waveform, high pass detection and integration means for generating a high pass integration signal representing the energy in a high pass band of said speech waveform, and first comparator means for generating a voicing function signal when the ratio of said low signal to said high pass signal exceeds a first predetermined threshold, second comparator means for generating a strong voicing function signal only when the ratio of said low pass signal to said high pass signal exceeds a second predetermined threshold and for generating a weak voicing signal when said ratio is less than or equal to said second predetermined threshold.
Claim 8
Dependent Claim
50 words
A digitizer as in claim 5 further including third comparator means for comparing said low pass integrated signal with a filtered noise level signal of said low pass integrated signal representing background noise thereby forming a power present signal when said low pass integrated signal exceeds said noise level signal.
Claim 9
Dependent Claim
40 words
A digitizer as in claim 6 further including: decision logic means for generating said voicing parameter in response to said strong voice signal, to said structure signal, to said periodicity signal or to said weak voice and said periodicity signal.
Claim 10
Dependent Claim
238 words
In a digital communication system operating in a multiframe format, a pitch detector comprising: converter means connected to receive an analog speech waveform for converting said waveform to a digital format in a predetermined time frame corresponding to said multiframe format, means for generating a digital signal representing absolute magnitude difference function, said digital signal having a predetermined number of samples representing variations in the pitch of said waveform and having a pattern of recurring maximum and minimum points over the pitch period, means for generating a first digital pitch signal representing the fundamental pitch of said waveform, multiple check means connected to receive said digital signal and said first pitch signal for generating a second digital pitch signal when one of said recurring minimum points is lower than the first pitch signal by interpolating over successive ones of said samples of said digital signal to generate said second pitch signal thereby representing the fundamental pitch of said waveform, periodicity means for generating a periodicity signal representing the ratio of one of said minimum points and one of said maximum points, and range restrictor means connected to receive said digital signal, said periodicity signal, and said second pitch signal for generating a third pitch signal representing the restriction of the range of said first pitch signal to a range of pitches within a predetermined tolerance of the average pitch if said periodicity signal is below a predetermined level.
Claim 11
Dependent Claim
238 words
In a digital communication system operating in a multiframe format, a pitch detector comprising: converter means connected to receive an analog speech waveform for converting said waveform to a digital format in a predetermined time frame corresponding to said multiframe format, means for generating a digital signal representing absolute magnitude difference function, said digital signal having a predetermined number of samples representing variations in the pitch of said waveform and having a pattern of recurring maximum and minimum points over the pitch period, means for generating a first digital pitch signal representing the fundamental pitch of said waveform, multiple check means connected to receive said digital signal and said first pitch signal for generating a second digital pitch signal when one of said recurring minimum points is lower than the first pitch signal by interpolating over successive ones of said samples of said digital signal to generate said second pitch signal thereby representing the fundamental pitch of said waveform, periodicity means for generating a periodicity signal representing the ratio of one of said minimum points and one of said maximum points, and range restrictor means connected to receive said digital signal, said periodicity signal, and said second pitch signal for generating a third pitch signal representing the restriction of the range of said first pitch signal to a range of pitches within a predetermined tolerance of the average pitch if said periodicity signal is below a predetermined level.
Claim 12
Dependent Claim
271 words
In a digital communication system operating in a multiframe format, a voicing detector connected to receive an analog speech waveform comprising: low pass detection and integration means for generating a low pass integrated signal representing the energy in a low frequency band of said waveform, high pass detection and integration means for generating a high pass integrated signal representing the energy in a high pass band of said waveform, first comparator means for generating a voicing function signal when the ratio of said low pass signal to said high pass signal exceeds a first predetermined threshold, second comparator means for generating a strong voicing function signal only when the ratio of said low pass signal to said high pass signal exceeds a second predetermined threshold and for generating a weak voicing signal when said ratio is less than or equal to said second threshold, third comparator means for comparing said low pass integrated signal with a filtered noise level signal of said low pass integrated signal representing background noise thereby forming a power present signal when said low pass integrated signal exceeds the noise level signal, means for determining the number of extreme maximum and minimum points occurring within a predetermined range in an absolute magnitude difference function level representing said waveform within a predetermined range thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number, and decision logic means for generating said voicing parameter in response to said strong voice signal, to said structure signal, to said periodicity signal, or to said weak voicing and said periodicity signal.
Claim 13
Dependent Claim
271 words
In a digital communication system operating in a multiframe format, a voicing detector connected to receive an analog speech waveform comprising: low pass detection and integration means for generating a low pass integrated signal representing the energy in a low frequency band of said waveform, high pass detection and integration means for generating a high pass integrated signal representing the energy in a high pass band of said waveform, first comparator means for generating a voicing function signal when the ratio of said low pass signal to said high pass signal exceeds a first predetermined threshold, second comparator means for generating a strong voicing function signal only when the ratio of said low pass signal to said high pass signal exceeds a second predetermined threshold and for generating a weak voicing signal when said ratio is less than or equal to said second threshold, third comparator means for comparing said low pass integrated signal with a filtered noise level signal of said low pass integrated signal representing background noise thereby forming a power present signal when said low pass integrated signal exceeds the noise level signal, means for determining the number of extreme maximum and minimum points occurring within a predetermined range in an absolute magnitude difference function level representing said waveform within a predetermined range thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number, and decision logic means for generating said voicing parameter in response to said strong voice signal, to said structure signal, to said periodicity signal, or to said weak voicing and said periodicity signal.
Claim 14
Dependent Claim
381 words
In a speech digitizer for use in a digital communication system operating in a multiframe format, the method comprising the steps of: generating in digital format in response to an analog speech waveform variable filter coefficient and power parameters representative of said waveform, generating a digital pitch parameter substantially representing the fundamental periodicity of said waveform, generating a digital voicing parameter representing whether said speech waveform is voiced or unvoiced, generating a digital signal representing an absolute magnitude difference function, said digital signal having a predetermined number of samples representing the variations in the pitch of said analog waveform and having a pattern of recurring maximum and minimum points over the frequency spectra, generating a first digital pitch signal representing the fundamental pitch of said sampled signal, generating a periodicity digital signal representing the ratio of one of said minimum and one of said maximum points, generating a second digital pitch signal when one of said recurring minimum points is lower than the first pitch signal by interpolating over successive ones of said digital signal to generate said second pitch signal, restricting the range of said pitch signal to a range of pitches within a predetermined tolerance of the average pitch if said periodicity signal is below a predetermined level whereby a third digital pitch signal is generated representing the best estimate with the restricted range, determining the number of extreme maximum and minimum points within a predetermined range of said difference function thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number, multiplexing said parameters into a digital serial data stream in said multiframe format where selected ones of the frames in said multiframe format occur as a synchronization frame, providing a synchronization code whereby said code is multiplexed into a portion of said synchronization frame, connecting signaling information to another portion of said synchronization frame, transmitting said digital serial stream, demultiplexing the transmitted parameters, the synchronization code, and the signaling information, receiving the demultiplexed transmitted signaling information, generating a periodic component signal representative of a random noise signal, mixing said component signals thereby forming a driving function signal, and generating a second analog signal thereby representing said first analog signal in response to said driving function signal.
Claim 15
Dependent Claim
381 words
In a speech digitizer for use in a digital communication system operating in a multiframe format, the method comprising the steps of: generating in digital format in response to an analog speech waveform variable filter coefficient and power parameters representative of said waveform, generating a digital pitch parameter substantially representing the fundamental periodicity of said waveform, generating a digital voicing parameter representing whether said speech waveform is voiced or unvoiced, generating a digital signal representing an absolute magnitude difference function, said digital signal having a predetermined number of samples representing the variations in the pitch of said analog waveform and having a pattern of recurring maximum and minimum points over the frequency spectra, generating a first digital pitch signal representing the fundamental pitch of said sampled signal, generating a periodicity digital signal representing the ratio of one of said minimum and one of said maximum points, generating a second digital pitch signal when one of said recurring minimum points is lower than the first pitch signal by interpolating over successive ones of said digital signal to generate said second pitch signal, restricting the range of said pitch signal to a range of pitches within a predetermined tolerance of the average pitch if said periodicity signal is below a predetermined level whereby a third digital pitch signal is generated representing the best estimate with the restricted range, determining the number of extreme maximum and minimum points within a predetermined range of said difference function thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number, multiplexing said parameters into a digital serial data stream in said multiframe format where selected ones of the frames in said multiframe format occur as a synchronization frame, providing a synchronization code whereby said code is multiplexed into a portion of said synchronization frame, connecting signaling information to another portion of said synchronization frame, transmitting said digital serial stream, demultiplexing the transmitted parameters, the synchronization code, and the signaling information, receiving the demultiplexed transmitted signaling information, generating a periodic component signal representative of a random noise signal, mixing said component signals thereby forming a driving function signal, and generating a second analog signal thereby representing said first analog signal in response to said driving function signal.
Claim 16
Dependent Claim
171 words
The method of claim 10 further including the steps of: generating a low pass integrated signal representing the energy in a low frequency band of the speech waveform, generating a high pass integrated signal representing the energy in a high pass band of the speech waveform, generating a voicing function signal when the ratio of said low pass signal to said high pass signal exceeds a first predetermined threshold, generating a strong voicing function signal only when the ratio of said low pass signal to said high pass signal exceeds a second predetermined threshold, generating a weak voicing signal when said ratio is less than or equal to said second threshold, comparing said low pass integrated signal with a filtered noise level signal representing background noise thereby forming a power present signal when said low pass signal exceeds said noise level signal, and generating said voicing parameter in response to said strong voice signal, to said structure signal, to said periodicity signal, or to said weak voice and said periodicity signal.
Claim 17
Dependent Claim
190 words
In a pitch detector for use in a digital communication system operating in a multiframe format, the method comprising the steps of: converting an analog speech waveform to a digital format in a predetermined time frame corresponding to said multiframe format, generating a digital signal representing an absolute magnitude difference function of said waveform, said digital signal having a predetermined number of samples representing the variations in the pitch of said waveform and having a pattern of recurring maximum and minimum points over the pitch period, generating a first digital pitch signal representing the fundamental pitch of said waveform, generating a second pitch signal when one of said multiple signals is lower than the first pitch signal by interpolating over successive ones of said samples of said digital signal to generate said second pitch signal thereby representing the fundamental pitch of said waveform, and determining the number of extreme maximum and minimum points occurring within a predetermined range in an absolute magnitude different function signal representing said waveform thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number.
Claim 18
Dependent Claim
190 words
In a pitch detector for use in a digital communication system operating in a multiframe format, the method comprising the steps of: converting an analog speech waveform to a digital format in a predetermined time frame corresponding to said multiframe format, generating a digital signal representing an absolute magnitude difference function of said waveform, said digital signal having a predetermined number of samples representing the variations in the pitch of said waveform and having a pattern of recurring maximum and minimum points over the pitch period, generating a first digital pitch signal representing the fundamental pitch of said waveform, generating a second pitch signal when one of said multiple signals is lower than the first pitch signal by interpolating over successive ones of said samples of said digital signal to generate said second pitch signal thereby representing the fundamental pitch of said waveform, and determining the number of extreme maximum and minimum points occurring within a predetermined range in an absolute magnitude different function signal representing said waveform thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number.
Claim 19
Dependent Claim
62 words
The method of claim 12 further comprising the steps of: generating an average digital periodicity signal representing the ratio of one of said maximum points and one of said minimum points, and restricting the range of said first pitch signal to a range of pitches within a predetermined tolerance of the average pitch if said periodicity signal is below a predetermined level.
Claim 20
Dependent Claim
234 words
In a voicing detector connected to receive an analog speech waveform for use in a digital communication system operating in a multiframe format, the method comprising the steps of: generating a low pass integrated signal representing the energy in a low frequency band of said waveform, generating a high pass integrated signal representing the energy in a high pass band of said waveform, generating a voicing function signal when the ratio of said low pass signal to said high pass signal exceeds a first predetermined threshold, generating a strong voicing function signal only when the ratio of said low pass signal to said high pass signal exceeds a second predetermined threshold, generating a weak voicing signal if said ratio is less than or equal to said second threshold, comparing said integrated low signal with a filtered noise level signal representing background noise thereby forming a power present signal when the low pass integrated signal exceeds the noise level signal, determining the number of extreme maximum and minimum points occurring within a predetermined range in an absolute magnitude difference function signal representing said waveform thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number, and generating said voicing parameter in response to said strong voice signal, to said structure signal, to said periodicity signal, or to said weak voicing and said periodicity signal.
Claim 21
Dependent Claim
234 words
In a voicing detector connected to receive an analog speech waveform for use in a digital communication system operating in a multiframe format, the method comprising the steps of: generating a low pass integrated signal representing the energy in a low frequency band of said waveform, generating a high pass integrated signal representing the energy in a high pass band of said waveform, generating a voicing function signal when the ratio of said low pass signal to said high pass signal exceeds a first predetermined threshold, generating a strong voicing function signal only when the ratio of said low pass signal to said high pass signal exceeds a second predetermined threshold, generating a weak voicing signal if said ratio is less than or equal to said second threshold, comparing said integrated low signal with a filtered noise level signal representing background noise thereby forming a power present signal when the low pass integrated signal exceeds the noise level signal, determining the number of extreme maximum and minimum points occurring within a predetermined range in an absolute magnitude difference function signal representing said waveform thereby generating a structure number signal representing a voiced event when the number of extreme points is less than a predetermined number, and generating said voicing parameter in response to said strong voice signal, to said structure signal, to said periodicity signal, or to said weak voicing and said periodicity signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-10-28 | 1984-04-28 | 1984-10-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-10-28 | 1988-04-28 | 1988-10-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-10-28 | 1992-04-28 | 1992-10-28 | $7700.00 | Window Closed / Lapsed |