US3700812A
Expired / Lapsed
US
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Audio system with means for reducing noise effects
Assignee: National Aeronautics and Space Administration
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Filing: 1971-03-11
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Granted: 1972-10-24
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Expires: 1991-03-11
Abstract
Abstract A system for eliminating noise pulses in the waveform of an audio signal is disclosed. The audio signal is used to produce an envelope signal whose amplitude is a function of the amplitude of a waveform section received during a time period T. The amplitude of the center segment of the waveform section is compared with the envelope signal amplitude. If the former is greater than the envelope signal amplitude it represents a noise pulse, and it is substituted by a pulse whose amplitude is either the envelope signal amplitude or the amplitude of a waveform segment adjacent to the noise representing segment.
Inventors
- 👤 James C Springett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 20:52
CPC Classifications
H; H04; H04B; H04B15/00
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
207 words
A system for reducing the effect of noise-producing signals contained among audio signals, which represent recorded sound, comprising: first means for receiving a sequence of said audio signals including said noise-producing signals; second means for generating an envelope signal whose amplitude is a function of the amplitudes of a succession of N sIgnals, last received by said first means, N representing a preselected integer; third means coupled to said second means and responsive to each received signal and including comparing means for comparing a preselected amplitude which is a function of said envelope signal with the amplitude of the center signal in the succession of said N signals, and for providing a first control signal when said preselected amplitude is less than said center signal amplitude and a second control signal when said preselected amplitude is not less than said center signal amplitude; and output means coupled to said second and third means and including gating means for receiving each center signal when said second control signal is provided and for receiving a substitute signal when said first control signal is provided, said substitute signal amplitude being a function of at least the amplitude of a signal adjacent said center signal in said succession of N signals.
Claim 2
Independent Claim
207 words
A system for reducing the effect of noise-producing signals contained among audio signals, which represent recorded sound, comprising: first means for receiving a sequence of said audio signals including said noise-producing signals; second means for generating an envelope signal whose amplitude is a function of the amplitudes of a succession of N sIgnals, last received by said first means, N representing a preselected integer; third means coupled to said second means and responsive to each received signal and including comparing means for comparing a preselected amplitude which is a function of said envelope signal with the amplitude of the center signal in the succession of said N signals, and for providing a first control signal when said preselected amplitude is less than said center signal amplitude and a second control signal when said preselected amplitude is not less than said center signal amplitude; and output means coupled to said second and third means and including gating means for receiving each center signal when said second control signal is provided and for receiving a substitute signal when said first control signal is provided, said substitute signal amplitude being a function of at least the amplitude of a signal adjacent said center signal in said succession of N signals.
Claim 3
Dependent Claim
20 words
The arrangement as recited in claim 1 wherein said substitute signal amplitude is a function of said envelope signal amplitude.
Claim 4
Dependent Claim
44 words
The arrangement as recited in claim 1 wherein said substitute signal amplitude is substantially equal to the amplitude of an audio signal adjacent said center signal, said adjacent audio signal having an amplitude which is not greater than the amplitude of said envelope signal.
Claim 5
Dependent Claim
29 words
The arrangement as recited in claim 3 wherein said adjacent audio signal precedes in said succession of N signals said center signal, whose amplitude exceeds said envelope signal amplitude.
Claim 6
Dependent Claim
74 words
The arrangement as recited in claim 1 wherein said system further includes means for sensing a sequence of noise producing signals each with an amplitude which exceeds said preselected amplitude with which its amplitude is compared, said system further including means in said output means for receiving for each of said noise-producing signals a signal whose amplitude is a function of the amplitude of a different adjacent signal in said succession of N signals.
Claim 7
Dependent Claim
29 words
The arrangement as recited in claim 5 wherein each noise-producing signal is substituted with a signal whose amplitude equals a different preceding signal in said succession of N signals.
Claim 8
Dependent Claim
28 words
The arrangement as recited in claim 1 wherein said preselected amplitude is equal to the envelope signal amplitude divided by a factor which is not less than one.
Claim 9
Dependent Claim
20 words
The arrangement as recited in claim 7 wherein said substitute signal amplitude is a function of said envelope signal amplitude.
Claim 10
Dependent Claim
44 words
The arrangement as recited in claim 7 wherein said substitute signal amplitude is substantially equal to the amplitude of an audio signal adjacent said center signal, said adjacent audio signal having an amplitude which is not greater than the amplitude of said envelope signal.
Claim 11
Dependent Claim
29 words
The arrangement as recited in claim 9 wherein said adjacent audio signal precedes in said succession of N signals said center signal, whose amplitude exceeds said envelope signal amplitude.
Claim 12
Dependent Claim
73 words
The arrangement as recited in claim 7 wherein said system further includes means for sensing a sequence of noise-producing signals each with an amplitude which exceeds said preselected amplitude with which its amplitude is compared, said system further including means in said output means for receiving for each of said noise-producing signals a signal whose amplitude is a function of the amplitude of a different adjacent signal in said succession of N signals.
Claim 13
Dependent Claim
247 words
An audio system to which a continuous signal in the audible range is applied, the system comprising: first means for receiving said continuous signal in the audible range and for producing a succession of equal duration pulses at a preselected frequency, each pulse having an amplitude and polarity which are a function of the amplitude and polarity of a corresponding section of said continuous signal; second means coupled to said first means and responsive to said pulses for generating an envelOpe signal whose amplitude is a function of the amplitudes of the last N received pulses from said first means, N representing a preselected integer; third means coupled to said first and second means and including comparing means for comparing the amplitude of the center pulse in the succession of said N pulses with a scaled amplitude which is a function of the amplitude of said envelope signal, and for providing a first control signal when said scaled amplitude is less than said center pulse amplitude and a second control signal when said scaled amplitude is not less than said center pulse amplitude; and output means coupled to said second and third means and including gating means for receiving each center pulse when said second control signal is provided and for receiving a substitute pulse when said first control signal is provided, said substitute pulse amplitude being a function of at least the amplitude of a pulse adjacent said center pulse in said succession of N pulses.
Claim 14
Dependent Claim
247 words
An audio system to which a continuous signal in the audible range is applied, the system comprising: first means for receiving said continuous signal in the audible range and for producing a succession of equal duration pulses at a preselected frequency, each pulse having an amplitude and polarity which are a function of the amplitude and polarity of a corresponding section of said continuous signal; second means coupled to said first means and responsive to said pulses for generating an envelOpe signal whose amplitude is a function of the amplitudes of the last N received pulses from said first means, N representing a preselected integer; third means coupled to said first and second means and including comparing means for comparing the amplitude of the center pulse in the succession of said N pulses with a scaled amplitude which is a function of the amplitude of said envelope signal, and for providing a first control signal when said scaled amplitude is less than said center pulse amplitude and a second control signal when said scaled amplitude is not less than said center pulse amplitude; and output means coupled to said second and third means and including gating means for receiving each center pulse when said second control signal is provided and for receiving a substitute pulse when said first control signal is provided, said substitute pulse amplitude being a function of at least the amplitude of a pulse adjacent said center pulse in said succession of N pulses.
Claim 15
Dependent Claim
20 words
The arrangement as recited in claim 12 wherein said substitute pulse amplitude is a function of said envelope signal amplitude.
Claim 16
Dependent Claim
40 words
The arrangement as recited in claim 12 wherein said substitute pulse amplitude is substantially equal to the amplitude of a pulse adjacent said center pulse, when said adjacent pulse has an amplitude which is not greater than said scaled amplitude.
Claim 17
Independent Claim
167 words
A method of reducing the effect of noise-producing signals contained among audio signals, which represent recorded sound, the steps comprising: receiving a sequence of said audio signals including said noise-producing signals; generating an envelope signal whose amplitude is a function of the amplitudes of a succession of N signals, last received by said first means, N representing a preselected integer; comparing a preselected amplitude which is a function of said envelope signal with the amplitude of the center signal in the succession of said N signals; providing a first control signal when said preselected amplitude is less than said center signal amplitude and a second control signal when said preselected amplitude is not less than said center signal amplitude; and receiving each center signal when said second control signal is provided and a substitute signal when said first control signal is provided, said substitute signal amplitude being a function of at least the amplitude of a signal adjacent said center signal in said succession of N signals.
Claim 18
Independent Claim
167 words
A method of reducing the effect of noise-producing signals contained among audio signals, which represent recorded sound, the steps comprising: receiving a sequence of said audio signals including said noise-producing signals; generating an envelope signal whose amplitude is a function of the amplitudes of a succession of N signals, last received by said first means, N representing a preselected integer; comparing a preselected amplitude which is a function of said envelope signal with the amplitude of the center signal in the succession of said N signals; providing a first control signal when said preselected amplitude is less than said center signal amplitude and a second control signal when said preselected amplitude is not less than said center signal amplitude; and receiving each center signal when said second control signal is provided and a substitute signal when said first control signal is provided, said substitute signal amplitude being a function of at least the amplitude of a signal adjacent said center signal in said succession of N signals.
Claim 19
Dependent Claim
20 words
The method as recited in claim 15 wherein said substitute signal amplitude is a function of said envelope signal amplitude.
Claim 20
Dependent Claim
44 words
The method as recited in claim 15 wherein said substitute signal amplitude is substantially equal to the amplitude of an audio signal adjacent said center signal, said adjacent audio signal having an amplitude which is not greater than the amplitude of said envelope 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) | 1975-10-24 | 1976-04-24 | 1976-10-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-10-24 | 1980-04-24 | 1980-10-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-10-24 | 1984-04-24 | 1984-10-24 | $7700.00 | Window Closed / Lapsed |