US3921077A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Noise reduction apparatus
Assignee: Sanyo Electric Co Ltd
•
Filing: 1974-06-06
•
Granted: 1975-11-18
•
Expires: 1994-06-06
Abstract
Abstract A noise reduction apparatus is provided which comprises a variable filter circuit which has a frequency characteristic which changes in response to an input signal of from a program source applied thereto so that the noise component of high frequency can be reduced and high fidelity reproduction of the input signal from the program source can be performed.
Inventors
- 👤 Kouzi Suzuki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 23:25
CPC Classifications
H; H03; H03G; H03G5/00; H03G5/16; H03G5/18; H03G5/22; H03H; H03H11/00; H03H11/02; H03H11/04; H03H11/12; H03H11/1213
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
250 words
A high frequency noise reduction apparatus comprising: a. a variable frequency band pass filter means having a variable frequency characteristic, for receiving a program source signal and high frequency noise and for attenuating the high frequency noise when the program source signal does not contain a high frequency component or when the amplitude of the program source signal is below a predetermined level, the frequency characteristic of said filter means varying in response to a compensation signal applied thereto; b. compensation signal amplifier means, having its input coupled to said filter means for receiving the program source signal from said filter means and for deriving a compensation signal therefrom, the output of said compensation signal amplifier means being coupled to said filter means for applying the compensation signal thereto; c. control signal amplifier means, having its input coupled to the output of said Compensation signal amplifier means, for generating a control signal when said program source signal includes a high frequency component or has an amplitude below the predetermined level; d. variable impedance circuit means, coupled between the output of said control signal amplifier means and the junction of the output of said compensation signal amplifier means and said filter means for controlling the compensation signal applied to said filter means in response to the control signal from said control signal amplifier such that no compensation signal is applied to said filter means when the source program signal contains high frequency components or has an amplitude above the predetermined level.
Claim 2
Dependent Claim
250 words
A high frequency noise reduction apparatus comprising: a. a variable frequency band pass filter means having a variable frequency characteristic, for receiving a program source signal and high frequency noise and for attenuating the high frequency noise when the program source signal does not contain a high frequency component or when the amplitude of the program source signal is below a predetermined level, the frequency characteristic of said filter means varying in response to a compensation signal applied thereto; b. compensation signal amplifier means, having its input coupled to said filter means for receiving the program source signal from said filter means and for deriving a compensation signal therefrom, the output of said compensation signal amplifier means being coupled to said filter means for applying the compensation signal thereto; c. control signal amplifier means, having its input coupled to the output of said Compensation signal amplifier means, for generating a control signal when said program source signal includes a high frequency component or has an amplitude below the predetermined level; d. variable impedance circuit means, coupled between the output of said control signal amplifier means and the junction of the output of said compensation signal amplifier means and said filter means for controlling the compensation signal applied to said filter means in response to the control signal from said control signal amplifier such that no compensation signal is applied to said filter means when the source program signal contains high frequency components or has an amplitude above the predetermined level.
Claim 3
Dependent Claim
77 words
The high frequency noise reduction apparatus of claim 1, wherein said filter means comprises a transistor and a capacitor means coupled between the base of said transistor and ground wherein the output of said compensation signal amplifier means and said variable impedance circuit means are coupled to said capacitor means such that the application of said compensation signal to said capacitor means eliminates current flow from the base of said transistor to ground through said capacitor means.
Claim 4
Dependent Claim
33 words
The high frequency noise reduction apparatus of claim 1, further including feedback means, coupled between said control signal amplifier means and said compensation signal amplifier means, for reducing distortion in the compensation 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) | 1978-11-17 | 1979-05-19 | 1979-11-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-11-17 | 1983-05-19 | 1983-11-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-11-17 | 1987-05-19 | 1987-11-18 | $7700.00 | Window Closed / Lapsed |