US3828133A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Speech quality improving system utilizing the generation of higher harmonic components
Assignee: KDDI Corp
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Filing: 1972-09-21
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Granted: 1974-08-06
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Expires: 1992-09-21
Abstract
Abstract A speech quality improving system for a band-limited voice signal, comprising a branching circuit for dividing the bandlimited voice signal into two branched signals each having the same waveform as the band-limited voice signal, a higher harmonic signal generator for generating higher harmonic components of one of the two branched signals, and a combining circuit for combining the other of the two branched signals with the generated higher harmonic components to provide a combined voice signal having an improved speech quality realized by increasing the higher harmonic components of the band-limited voice signal. The higher harmonic generator comprises a cascade combination of an instantaneous compressor and a level range expander having reciprocal power characteristics of the compression ratio of the instantaneous compressor.
Inventors
- 👤 H Ishigami
- 👤 S Kitayama
- 👤 A Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:06
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/66
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
221 words
A system for improving the quality of a band-limited voice signal comprising: a. a dividing circuit receptive of a band-limited voice signal for providing in response thereto a first and second output signal having waveforms identical to a waveform of said bandlimited voice signal; b. a harmonic signal generator receptive of said dividing circuit first signal for providing in response thereto an output signal comprising harmonics of said band-limited voice signal, said harmonic signal generator comprising an instantaneous compressor circuit receptive of said dividing circuit first signal for providing in response thereto an output signal having frequency components corresponding to frequency components of said band-limited voice signal but reduced in amplitude to 1/v of the amplitude of said bandlimited voice signal frequency components where v is a real number, and a level range expanding circuit receptive of said instantaneous compressor circuit output signal for providing in response thereto said harmonic signal generator output signal having high frequency components of a signal equal to the v-th power of said instantaneous compressor circuit output signal; and c. a combining circuit receptive of said harmonic signal generator output signal and said dividing circuit second output signal for providing in response thereto an output signal having frequency components corresponding to the frequency components of said band-limited voice signal and harmonics of said band-limited voice signal.
Claim 2
Independent Claim
221 words
A system for improving the quality of a band-limited voice signal comprising: a. a dividing circuit receptive of a band-limited voice signal for providing in response thereto a first and second output signal having waveforms identical to a waveform of said bandlimited voice signal; b. a harmonic signal generator receptive of said dividing circuit first signal for providing in response thereto an output signal comprising harmonics of said band-limited voice signal, said harmonic signal generator comprising an instantaneous compressor circuit receptive of said dividing circuit first signal for providing in response thereto an output signal having frequency components corresponding to frequency components of said band-limited voice signal but reduced in amplitude to 1/v of the amplitude of said bandlimited voice signal frequency components where v is a real number, and a level range expanding circuit receptive of said instantaneous compressor circuit output signal for providing in response thereto said harmonic signal generator output signal having high frequency components of a signal equal to the v-th power of said instantaneous compressor circuit output signal; and c. a combining circuit receptive of said harmonic signal generator output signal and said dividing circuit second output signal for providing in response thereto an output signal having frequency components corresponding to the frequency components of said band-limited voice signal and harmonics of said band-limited voice signal.
Claim 3
Dependent Claim
56 words
A system for improving the quality of a band-limited voice signal according to claim 1, wherein said level range expanding circuit comprises, an expander having an output signal to input signal ratio equal to v and a band pass filter receptive of the expander output signal for passing high harmonic components of the expander output signal.
Claim 4
Dependent Claim
82 words
A system for improving the quality of a band-limited voice signal according to claim 1, wherein said level range expanding circuit comprises, an oscillator providing a carrier signal, a modulator receptive of said carrier signal and said instantaneous compressor circuit output signal for providing an output signal comprising said carrier signal modulated by said instantaneous compressor circuit output signal, and a frequency converting circuit receptive of said carrier signal and said modulator output signal for providing harmonics of said modulator output signal.
Claim 5
Dependent Claim
67 words
A system for improving the quality of a band-limited voice signal according to claim 2, wherein said frequency converting circuit comprises a frequency converter receptive of said carrier signal and said modulated carrier signal for providing harmonics of said modulator output signal, and a lowpass filter receptive of said harmonics of said modulator output signal for providing high harmonic components from the output of said frequency converter.
Claim 6
Dependent Claim
105 words
A system for improving the quality of a band-limited voice signal according to claim 2, wherein said frequency converting circuit comprises, a bandpass filter receptive of said modulator output signal for extracting said carrier signal therefrom, a synchronous oscillator receptive of said carrier signal from said bandpass filter for providing an oscillating output signal synchronized with said carrier signal, a frequency converter receptive of said modulator output signal and said synchronous oscillator output signal for providing harmonics of said modulator output signal, and a low pass filter receptive of said harmonics of said modulator output signaL for filtering said harmonics of said modulator output signal.
Claim 7
Dependent Claim
183 words
A system for improving the quality of a band-limited voice signal according to claim 2, wherein said frequency converting circuit comprises, a bandpass filter receptive of said modulator output signal for extracting said carrier signal therefrom, a synchronous oscillator receptive of said carrier signal from said bandpass filter for providing an oscillating output signal synchronized with said carrier signal, a first frequency converter receptive of said modulator output signal and said synchronous oscillator output signal for providing odd and even harmonics of said modulator output signal, a first lowpass filter receptive of said first frequency converter output signal for providing one of said odd and even harmonics of said modulator output signal, a 90* phase shifter receptive of said synchronous oscillator output signal for providing an output in response thereto, a second frequency converter receptive of said modulator output signal and said 90* phase shifter output signal for providing harmonics of said modulator output signal, and a second lowpass filter receptive of said second frequency converter output signal for providing the other of said odd and even harmonics of said modulator output signal.
Claim 8
Dependent Claim
134 words
A system for improving the quality of a band-limited voice signal according to claim 2, wherein said frequency converting circuit comprises, a first frequency convertor receptive of said modulator output signal and said carrier signal for providing odd and even harmonics of said modulator output signal, a first low pass filter receptive of said first frequency converter output signal for providing one of said odd and even harmonics of said modulator output signal, a 90* phase shifter receptive of said carrier signal for providing an output in response thereto, a second frequency converter receptive of said modulator output signal for providing harmonics of said modulator output signal, and a second lowpass filter receptive of said frequency converter output signal for providing the other of said odd and even harmonics of said modulator output signal.
Claim 9
Dependent Claim
145 words
A system for improving the quality of a band-limited voice signal according to claim 1, wherein said harmonic signal generator comprises; a branching circuit receptive of said dividing circuit first output signal for providing a plurality of output signals each identical to said dividing circuit first output signal, a plurality of filters each receptive of one of said branching circuit output signals to provide output signals having different frequency bands filtered therefrom, a plurality of harmonic generators each receptive of a filter output signal for providing harmonics thereof, a plurality of weighting circuits each receptive of said harmonics of a different one of said filter output signals for providing output signals having frequency components corresponding to said harmonics and amplitudes determined by said weighting circuits, and a second combining circuit for combining said weighting circuit output signals to provide said harmonic signal generator output 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) | 1977-08-05 | 1978-02-04 | 1978-08-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-05 | 1982-02-04 | 1982-08-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-05 | 1986-02-04 | 1986-08-06 | $7700.00 | Window Closed / Lapsed |