Patent US4054751A successfully refreshed from Google Patents.
US4054751A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Masking noise generator
Assignee: CDF IND Inc
•
Filing: 1976-03-01
•
Granted: 1977-10-18
•
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 05:43
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.
References Cited (Backward Citations)
US3213199A
Cited
US3567863A
Cited
US3614399A
Cited
US3681708A
Cited
GB1420201A
Cited
US3885139A
Cited
US3980827A
Cited
US4024535A
Cited
US4024535B1
Cited
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 |