US3663747A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Television receiver with phase detector controlled sound suppression filter
Assignee: US Philips Corp
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Filing: 1969-12-03
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Granted: 1972-05-16
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Expires: 1989-12-03
Abstract
Abstract A television receiver has video and audio I.F. sections. An audio carrier trap with a varactor tuned diode is located in either a common I.F. section or the video I.F. section. A phase detector has two inputs coupled to the audio and video sections respectively and an output coupled to the varactor diode. Therefore, as the local oscillator is adjusted, the audio trap is always tuned to the sound carrier.
Inventors
- 👤 Peter Johannes Hubertu Janssen
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:51
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/44; H04N5/60; H04N5/62
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
132 words
A circuit comprising a first channel having an input coupled to receive a signal having a carrier and a subcarrier and having an output; a second channel having an input coupled to said first channel output; a third channel having an input coupled to said first channel output; first filter means for suppressing said subcarrier coupled to said second channel; said filter means having a variable reactancE element and producing phase variations of said subcarrier upon departure of the frequency of the subcarrier from the attenuating frequency of the filter means; and a phase detector having two inputs coupled to said second and third channels respectively and an output means coupled to said element for supplying a control signal thereto to keep said filter tuned to the subcarrier frequency for suppression thereof.
Claim 2
Dependent Claim
132 words
A circuit comprising a first channel having an input coupled to receive a signal having a carrier and a subcarrier and having an output; a second channel having an input coupled to said first channel output; a third channel having an input coupled to said first channel output; first filter means for suppressing said subcarrier coupled to said second channel; said filter means having a variable reactancE element and producing phase variations of said subcarrier upon departure of the frequency of the subcarrier from the attenuating frequency of the filter means; and a phase detector having two inputs coupled to said second and third channels respectively and an output means coupled to said element for supplying a control signal thereto to keep said filter tuned to the subcarrier frequency for suppression thereof.
Claim 3
Dependent Claim
58 words
A circuit as claimed in claim 1 further comprising a first and second detectors coupled within said second and third channels respectively, the detector of said second channel being coupled between said filter and one of said phase detectors inputs, the remaining detector being coupled in said third channel between said first channel and the remaining detector input.
Claim 4
Dependent Claim
43 words
A circuit as claimed in claim 1 wherein said first filter is coupled to said second channel and further comprising a second filter means for suppressing said subcarrier coupled to said first channel having a variable reactance element coupled to said detector output.
Claim 5
Dependent Claim
54 words
A circuit as claimed in claim 1 wherein said first channel comprises a mixer having a first input coupled to receive a television signal, a second input, and an output; an oscillator coupled to said mixer second input; and an IF amplifier coupled to said mixer output; whereby said subcarrier comprises an audio subcarrier.
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) | 1975-05-16 | 1975-11-15 | 1976-05-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-05-16 | 1979-11-15 | 1980-05-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-05-16 | 1983-11-15 | 1984-05-16 | $7700.00 | Window Closed / Lapsed |