US4054751A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Masking noise generator
Assignee: CDF IND Inc
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Filing: 1976-03-01
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Granted: 1977-10-18
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Expires: 1996-03-01
Abstract
Abstract There is disclosed a masking noise generator which includes a digital means such as a shift register for generating noise signals wherein the output of the shift register is fed via a filtering means to a transducer means such as a speaker for converting the noise signals to acoustic waves.
Inventors
- 👤 George Donald Calder
- 👤 John Duda
- 👤 John Fatovic
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 01:35
CPC Classifications
H; H04; H04K; H04K1/00; H04K1/02; G; G10; G10K; G10K11/00; G10K11/16; G10K11/175; G10K11/1752; G10K11/1754; H04K3/00; H04K3/40; H04K3/42; H04K3/43; H04K3/80; H04K3/82; H04K3/825; H04R; H04R3/00; H04K2203/00; H04K2203/10; H04K2203/12
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
143 words
Apparatus for generating audible masking noise comprising: a multi-stage shift register having an input and at least two outputs connected to two different stages, an exclusive-or means having two inputs respectively connected to the outputs of said two stages and an output connected to the input of said shift register; means for generating shift pulses for shifting said shift register; a low-pass filter for passing signals only in the audio range, said low-pass filter having an input connected to one of the outputs of said multi-stage shift register and an output; a signal clipping amplifier means having an input connected to the output of said low-pass filter and an output; a spectral shaping filter having an input connected to the output of said signal clipping amplifier means and an output; and a loud speaker connected to the output of said spectral shaping filter.
Claim 2
Dependent Claim
143 words
Apparatus for generating audible masking noise comprising: a multi-stage shift register having an input and at least two outputs connected to two different stages, an exclusive-or means having two inputs respectively connected to the outputs of said two stages and an output connected to the input of said shift register; means for generating shift pulses for shifting said shift register; a low-pass filter for passing signals only in the audio range, said low-pass filter having an input connected to one of the outputs of said multi-stage shift register and an output; a signal clipping amplifier means having an input connected to the output of said low-pass filter and an output; a spectral shaping filter having an input connected to the output of said signal clipping amplifier means and an output; and a loud speaker connected to the output of said spectral shaping filter.
Claim 3
Dependent Claim
56 words
The apparatus of claim 1 wherein said spectal shaping filter comprises a π-section with each leg thereof comprising a resistor and capacitor connected in series and a branch member comprising a resistor, and a further resistor connecting the input of said spectral shaping filter to the junction of one of said legs and said branch member.
Claim 4
Dependent Claim
43 words
The apparatus of claim 2 wherein said low-pass filter comprises a resistor connecting an output of said multistage shift register to the input of said signal clipping amplifier means and a capacitor connecting the input of said signal clipping amplifier means to ground.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-10-17 | 1981-04-18 | 1981-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-10-17 | 1985-04-18 | 1985-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-10-17 | 1989-04-18 | 1989-10-18 | $7700.00 | Window Closed / Lapsed |