Patent US3944725A successfully refreshed from Google Patents.
US3944725A
Expired / Lapsed
US
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Wide band automatic frequency control circuit
Assignee: GTE Sylvania Inc
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Filing: 1975-02-28
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Granted: 1976-03-16
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Expires: 1995-02-28
Abstract
Abstract An automatic frequency control (AFC) circuit for a signal receiver having a tuner, intermediate frequency (IF) amplifier, video amplifier, and sync pulse separation means includes a discriminator coupled to the IF stage and a signal combining means coupled to the discriminator means and sync pulse separation means and to the tuner to effect a given "pull-in" range for the tuner in response to error signals from the discriminator and an increased "pull-in" range upon loss of sync signals from the sync pulse separation means when the tuner stage is increasingly detuned.
Inventors
- 👤 Rangaswamy Arumugham
- 👤 William Frank Kruszewski
- 👤 Karol Siwko
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 15:04
CPC Classifications
H; H03; H03J; H03J7/00; H03J7/02; H03J7/04; H04; H04N; H04N5/00; H04N5/44; H04N5/50
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
139 words
In a television receiver having an intermediate frequency (IF) amplifier stage coupled to a tuner stage and by a detector stage to a video amplifier stage connected to a cathode ray tube, an automatic frequency control (AFC) circuit comprising: discriminator means coupled to said IF amplifier stage for providing an error signal in response to signals deviating from the tuned frequency of said discriminator means; means coupled to said video amplifier stage for detecting sync pulses; and signal combining means coupling said discriminator means and said means for detecting sync pulses to said tuner stage for effecting a given "pull-in" range of said tuner stage in response to error signals from said discriminator means and an increased "pull-in" range in response to a signal from said means for detecting sync pulses indicative of the absence of detected sync pulses.
Claim 2
Dependent Claim
139 words
In a television receiver having an intermediate frequency (IF) amplifier stage coupled to a tuner stage and by a detector stage to a video amplifier stage connected to a cathode ray tube, an automatic frequency control (AFC) circuit comprising: discriminator means coupled to said IF amplifier stage for providing an error signal in response to signals deviating from the tuned frequency of said discriminator means; means coupled to said video amplifier stage for detecting sync pulses; and signal combining means coupling said discriminator means and said means for detecting sync pulses to said tuner stage for effecting a given "pull-in" range of said tuner stage in response to error signals from said discriminator means and an increased "pull-in" range in response to a signal from said means for detecting sync pulses indicative of the absence of detected sync pulses.
Claim 3
Dependent Claim
49 words
An automatic frequency control (AFC) circuit as defined in claim 1 wherein said means for detecting sync pulses includes a sync pulse separation means coupled to said video amplifier stage and a sync pulse detector stage coupled to said sync pulse separation means and to said signal combining means.
Claim 4
Dependent Claim
56 words
An automatic frequency control (AFC) circuit as defined in claim 1 wherein said signal combining means includes an amplifier stage having an output electrode coupled to a potential source and to said tuner stage, a first input electrode coupled to said discriminator means, and a second input electrode coupled to said means for detecting sync pulses.
Claim 5
Dependent Claim
39 words
An automatic frequency control (AFC) circuit as defined in claim 3 wherein said discriminator means includes a bias development means for effecting saturation conduction of said amplifier stage for error signals indicative of frequencies below the desired tuning frequency.
Claim 6
Dependent Claim
31 words
An automatic frequency control (AFC) circuit as defined in claim 4 wherein said bias development means includes a pair of resistors series coupling a potential source to a potential reference level.
Claim 7
Dependent Claim
142 words
An automatic frequency control (AFC) circuit for a signal receiver having an intermediate frequency (IF) amplifier stage coupling a tuner stage to a detector stage with a video amplifier stage coupling the detector stage to a cathode ray tube and to a sync pulse separation means comprising: discriminator means coupled to said IF amplifier stage and including a bias development means; means coupled to said video amplifier stage for detecting sync pulses; and signal combining means coupled to said discriminator means, to said means for detecting sync pulses, and to said tuner stage for coupling of an error signal from said discriminator means to said tuner stage to cause alteration in tuning frequency with a given "pull-in" range of said tuner stage and an increase of said "pull-in" range upon a loss of a signal from said means for detecting sync pulses.
Claim 8
Dependent Claim
142 words
An automatic frequency control (AFC) circuit for a signal receiver having an intermediate frequency (IF) amplifier stage coupling a tuner stage to a detector stage with a video amplifier stage coupling the detector stage to a cathode ray tube and to a sync pulse separation means comprising: discriminator means coupled to said IF amplifier stage and including a bias development means; means coupled to said video amplifier stage for detecting sync pulses; and signal combining means coupled to said discriminator means, to said means for detecting sync pulses, and to said tuner stage for coupling of an error signal from said discriminator means to said tuner stage to cause alteration in tuning frequency with a given "pull-in" range of said tuner stage and an increase of said "pull-in" range upon a loss of a signal from said means for detecting sync pulses.
Claim 9
Dependent Claim
39 words
An automatic frequency control (AFC) circuit as defined in claim 6 wherein said bias development means of said discriminator means causes saturation conduction of said signal combining means for error signals indicative of frequencies below the desired tuning frequency.
Claim 10
Dependent Claim
52 words
An automatic frequency (AFC) circuit as defined in claim 6 wherein said signal combining means includes a transistor having a base electrode coupled to said discriminator means, an emitter electrode coupled to said means for detecting sync pulses, and a collector electrode coupled to a potential source and to said tuner stage.
Claim 11
Dependent Claim
41 words
An automatic frequency control (AFC) circuit as defined in claim 6 wherein said means for detecting sync pulses includes said sync pulse separation means and a detector stage coupled to said sync pulse separation means and to said signal combining means.
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) | 1979-03-16 | 1979-09-15 | 1980-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-03-16 | 1983-09-15 | 1984-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-03-16 | 1987-09-15 | 1988-03-16 | $7700.00 | Window Closed / Lapsed |