US3761835A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic frequency control system
Assignee: US Philips Corp
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Filing: 1971-10-14
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Granted: 1973-09-25
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Expires: 1991-10-14
Abstract
Abstract The present invention relates to an automatic frequency control (AFC) system for controlling the frequency of an oscillator.
Inventors
- 👤 J Cook
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:16
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/18; H03L7/181; H03L7/08; H03L7/085; H03L7/097
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
151 words
A circuit for automatically controlling the frequency of a voltage controlled oscillator in accordance with a reference signal comprising means coupled to receive said reference signal for measuring in binary form the frequency of said signal; reference store means coupled to said measuring means for storing a binary digital signal representative of the required frequency of said oscillator; means adapted to be coupled to said oscillator for obtaining in binary digital form the actual frequency of said oscillator; means coupled to said reference store means and said obtaining means for subtracting at periodic intervals the binary digital numbers therein to produce successive digital difference signals; digital accumulating means coupled to said subtracting means for successively adding said difference signals; and means coupled to said accumulating means and adapted to be coupled to said oscillator for converting said digital difference signals into an analogue voltage for controlling the frequency of said oscillator.
Claim 2
Dependent Claim
151 words
A circuit for automatically controlling the frequency of a voltage controlled oscillator in accordance with a reference signal comprising means coupled to receive said reference signal for measuring in binary form the frequency of said signal; reference store means coupled to said measuring means for storing a binary digital signal representative of the required frequency of said oscillator; means adapted to be coupled to said oscillator for obtaining in binary digital form the actual frequency of said oscillator; means coupled to said reference store means and said obtaining means for subtracting at periodic intervals the binary digital numbers therein to produce successive digital difference signals; digital accumulating means coupled to said subtracting means for successively adding said difference signals; and means coupled to said accumulating means and adapted to be coupled to said oscillator for converting said digital difference signals into an analogue voltage for controlling the frequency of said oscillator.
Claim 3
Dependent Claim
15 words
A circuit as claimed in claim 1 wherein said obtaining means comprises said measuring means.
Claim 4
Dependent Claim
23 words
A circuit as claimed in claim 1 wherein said accumulating means comprises a binary adder and a binary store coupled to said adder.
Claim 5
Dependent Claim
82 words
A circuit as claimed in claim 1 further comprising first and second switches, each of said switches comprising a first input adapted to be coupled to receive said reference signal and to said oscillator respectively, a control input, and an output; a source of switching signals having a pair of complementary outputs coupled to said control inputs respectively; and a directional coupler having an input coupled to said switch outputs, and an output coupled to said frequency measuring and said obtaining means.
Claim 6
Dependent Claim
15 words
A circuit as claimed in claim 4 wherein said switches each comprise a PIN diode.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-09-24 | 1977-03-26 | 1977-09-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-09-24 | 1981-03-26 | 1981-09-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-09-24 | 1985-03-26 | 1985-09-25 | $7700.00 | Window Closed / Lapsed |