US3603889A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase comparator using flip-flop circuits
Assignee: AC Cossor Ltd
•
Filing: 1969-04-16
•
Granted: 1971-09-07
•
Expires: 1989-04-16
Abstract
Abstract A bistable flip-flop is set and reset respectively by two signals whose phases are to be compared and provides pulses of width determined by the phase difference. In order to prevent erroneous indication of phase synchronism when one signal frequency is an integral multiple of the other, a frequency comparator blocks the flip-flop when the frequencies are different and itself provides the said pulses, instead of the flip-flop.
Inventors
- 👤 Michael Charles Stevens
- 👤 Brian David Swatton
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:01
CPC Classifications
H; H03; H03K; H03K5/00; H03K5/22; H03K5/26
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
257 words
In combination, for comparing the phases of first and second periodic signals, a first bistable flip-flop having a first input responsive to said first signal for setting said flip-flop at an instant determined by the phase of said first signal, and a second input responsive to said second signal for resetting said flip-flop at an instant determined by the phase of said second signal, a first output line connected to said flip-flop to supply first output pulses as said flip-flop sets and resets, a second flip-flop having a first input responsive to said second signal for setting said second flip-flop at an instant determined by the phase of said second signal, and a second input responsive to said first signal for resetting said second flip-flop at an instant determined by the phase of said second signal, a second output line connected to said second flip-flop to supply second output pulses as said flip-flop sets and resets, a frequency comparator comprising first comparing means for providing first further output pulses when said first signal has a higher frequency than said second signal and second comparing means for providing second further output pulses when said second signal has a higher frequency than said first signal, means for applying said first further output pulses to said first output line, and means for applying said second further output pulses to said second output line, and inhibit means being responsive to both said first further output pulses and said second further output pulses for preventing both said first and second flip-flops setting.
Claim 2
Dependent Claim
257 words
In combination, for comparing the phases of first and second periodic signals, a first bistable flip-flop having a first input responsive to said first signal for setting said flip-flop at an instant determined by the phase of said first signal, and a second input responsive to said second signal for resetting said flip-flop at an instant determined by the phase of said second signal, a first output line connected to said flip-flop to supply first output pulses as said flip-flop sets and resets, a second flip-flop having a first input responsive to said second signal for setting said second flip-flop at an instant determined by the phase of said second signal, and a second input responsive to said first signal for resetting said second flip-flop at an instant determined by the phase of said second signal, a second output line connected to said second flip-flop to supply second output pulses as said flip-flop sets and resets, a frequency comparator comprising first comparing means for providing first further output pulses when said first signal has a higher frequency than said second signal and second comparing means for providing second further output pulses when said second signal has a higher frequency than said first signal, means for applying said first further output pulses to said first output line, and means for applying said second further output pulses to said second output line, and inhibit means being responsive to both said first further output pulses and said second further output pulses for preventing both said first and second flip-flops setting.
Claim 3
Dependent Claim
118 words
The combination as in claim 1, wherein said first signal consists of short pulses and said second signal consists of broad pulses, said first flip-flop setting in response to a short pulse occurring in front of the leading edge of a broad pulse and resetting on the leading edge of a broad pulse, the combination further comprising means for generating second short pulses from the leading edges of said broad pulses and means for stretching the first-said short pulses to generate second broad pulses, said second flip-flop setting in response to a second short pulse occurring in front of the leading edge of a second broad pulse and resetting on the leading edge of a second broad pulse.
Claim 4
Dependent Claim
66 words
The combination as in claim 1, wherein said signals consist of pulses and each said comparing means comprises two flip-flops connected as a divide-by-four counter to divide the pulses in one of said signals and to be reset by the pulses in other of said signals, the second flip-flop in each said comparing means providing the corresponding further output pulses when this flip-flop sets and resets.
Claim 5
Dependent Claim
71 words
A frequency locking system comprising the combination as in claim 1, a voltage controlled oscillator, means for dividing the output of said oscillator by N to provide one of said signals, a frequency standard fo providing the other of said signals, and means responsive to pulses in said first and second output lines for increasing and decreasing the control voltage to said oscillator to maintain the frequency thereof equal to Nfo.
References Cited (Backward Citations)
US3381220A
Cited
US3431509A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-09-06 | 1975-03-08 | 1975-09-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-09-06 | 1979-03-08 | 1979-09-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-09-06 | 1983-03-08 | 1983-09-07 | $7700.00 | Window Closed / Lapsed |