US3898375A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Notch rejection filter
Assignee: RCA Licensing Corp
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Filing: 1973-12-13
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Granted: 1975-08-05
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Expires: 1993-12-13
Abstract
Abstract The filter is of a bridged-T construction, and includes a pair of semiconductor rectifiers in back-to-back relationship. An oscillation voltage is applied to the junction of the rectifiers to vary their reverse biases and the junction capacities they exhibit. The variations in notch frequency which result are selected to overlap possible drift in filter tuning and provide continued signal rejection in the presence of such changes.
Inventors
- 👤 William James Hannan
- 👤 Robert Shelby Singleton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 05:35
CPC Classifications
H; H03; H03H; H03H7/00; H03H7/01; H03H7/17; H03H7/1741; H03H7/1766; H03H7/06; H03H7/07; H03J; H03J5/00; H04; H04B; H04B3/00; H04B3/02; H04B3/36; H04N; H04N7/00; H04N7/16; H04N7/166
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
105 words
A signal translating circuit comprising: a frequency selective network tuned to block the passage of applied signals of a given frequency from an input terminal to an output terminal and to enable the passage of applied signals of other frequencies between said terminals; and first means for cyclically varying the frequency selectivity characteristics of said network to establish a range of signal frequencies to be blocked, including and around said given frequency, to thereby offset random variations in said selectivity characteristics otherwise tending to detune said network and permit the undesired translation of applied signals of said given frequency between said input and output terminals.
Claim 2
Dependent Claim
105 words
A signal translating circuit comprising: a frequency selective network tuned to block the passage of applied signals of a given frequency from an input terminal to an output terminal and to enable the passage of applied signals of other frequencies between said terminals; and first means for cyclically varying the frequency selectivity characteristics of said network to establish a range of signal frequencies to be blocked, including and around said given frequency, to thereby offset random variations in said selectivity characteristics otherwise tending to detune said network and permit the undesired translation of applied signals of said given frequency between said input and output terminals.
Claim 3
Dependent Claim
47 words
The signal translating circuit of claim 1 wherein said frequency selective network comprises inductive and capacitive components and wherein said first means varies the capacitive reactance within said network to continuously vary the signal frequency which said translating circuit would block at any one instant of time.
Claim 4
Dependent Claim
67 words
The signal translating circuit of claim 2 wherein said frequency selective network comprises an inductor coupled between said input and output terminals and a pair of capacitive components serially connected across said inductor to tune said network, and wherein said first means varies the effective capacitance exhibited by said capacitive components to continuously vary the tuning of said network and the signal frequencies to be blocked thereby.
Claim 5
Dependent Claim
73 words
The signal translating circuit of claim 3 wherein said pair of capacitive components comprises a pair of capacitors serially coupled between said input and output terminals and a pair of semiconductor rectifiers individually connected in opposite polarity direction across respective ones of said capacitors, and wherein said first means includes means for applying a continuously varying voltage to reverse bias each of said semiconductor rectifiers and to vary the capacitance characteristics exhibited thereby.
Claim 6
Dependent Claim
65 words
The signal translating circuit of claim 4 for use in blocking the passage of an applied television signal of said given frequency from said input terminal to said output terminal, further comprising second means for controllably varying the frequency selectivity characteristics of said network to enable the passage of even said television signal of said given frequency upon the receipt of a supplied control signal.
Claim 7
Dependent Claim
76 words
The signal translating circuit of claim 5 wherein said second means comprises a third capacitor serially connected with a switch means across said inductor, with said switch means being held in an open-circuit condition in the absence of said supplied control signal and being held in a closed-circuit condition in the presence of said supplied control signal, whereby said frequencY selective network is detuned away from said given frequency upon the receipt of said control signal.
Claim 8
Dependent Claim
31 words
The signal translating circuit of claim 6 for use in a pay television system, wherein said control signal for said switch means is supplied when such television service is subscribed for.
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) | 1978-08-04 | 1979-02-03 | 1979-08-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-08-04 | 1983-02-03 | 1983-08-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-08-04 | 1987-02-03 | 1987-08-05 | $7700.00 | Window Closed / Lapsed |