US3764925A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Demodulator circuit
Assignee: US Philips Corp
•
Filing: 1972-01-26
•
Granted: 1973-10-09
•
Expires: 1992-01-26
Abstract
Abstract A synchronous demodulator circuit for a television receiver in which interference signals corresponding to troublesome white are obviated by full-wave rectification of the signal demodulated by the circuit arrangement.
Inventors
- 👤 Nikelsberg K Von
- 👤 G Kool
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 00:48
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/44; H04N5/455
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
119 words
A circuit for demodulating a television signal modulated carrier using a reference signal having the same phase and frequency as said modulated carrier; said circuit comprising a first circuit means having a first input means for receiving said modulated carrier, a second input means for receiving said reference signal, and a balanced output means for supplying a pair of opposite polarity balanced demodulated television output signals; and means for preventing interference signals from exceeding a selected level of said demodulated signal comprising a full wave rectifier having a pair of inputs coupled to said balanced output means, and an output means for supplying an output signal comprising said demodulated television signal and at most a reduced amplitude interference signal.
Claim 2
Dependent Claim
119 words
A circuit for demodulating a television signal modulated carrier using a reference signal having the same phase and frequency as said modulated carrier; said circuit comprising a first circuit means having a first input means for receiving said modulated carrier, a second input means for receiving said reference signal, and a balanced output means for supplying a pair of opposite polarity balanced demodulated television output signals; and means for preventing interference signals from exceeding a selected level of said demodulated signal comprising a full wave rectifier having a pair of inputs coupled to said balanced output means, and an output means for supplying an output signal comprising said demodulated television signal and at most a reduced amplitude interference signal.
Claim 3
Dependent Claim
52 words
A circuit as claimed in claim 1 wherein said full wave rectifier comprises a pair of transistors having emitters coupled to each other, opposite polarity driven bases coupled to said balanced output respectively, and collectors adapted to be coupled to a voltage supply, said rectifier output means being coupled to said emitters.
Claim 4
Dependent Claim
42 words
A circuit as claimed in claim 1 wherein said rectifier comprises a pair of diodes having a first set of like electrodes coupled to said balanced output means respectively, and a second pair of like electrodes coupled to said rectifier oUtput means.
Claim 5
Dependent Claim
60 words
A circuit as claimed in claim 2 wherein said first circuit means comprises a first transistor having an emitter and base coupled to receive said modulated signal, and a collector; second and third transistors having emitters coupled to said first transistor collector, bases coupled to receive said reference signal, and collectors coupled to said bases of said transistor pair respectively.
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) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |