US3893040A
Expired / Lapsed
US
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Digital automatic frequency control system
Assignee: AG Communication Systems Corp
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Filing: 1974-03-27
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Granted: 1975-07-01
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Expires: 1994-03-27
Abstract
Abstract This invention relates to an automatic frequency control system wherein analog and digital techniques are utilized to detect and correct an off-frequency condition of a controlled oscillator. Digital circuits determine the operating frequency of this oscillator and produce a discrete error voltage when an offfrequency condition exists. The error voltage is then fed back to the oscillator for use in correcting the off-frequency condition.
Inventors
- 👤 Maurice C Harp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 11:40
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/06; H03L7/16; H03L7/18; H03L7/181
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
163 words
An automatic frequency control system wherein the frequency of an oscillator is periodically determined during intervals of time precisely controlled to derive indications of the frequency thereof for controlling said frequency, said sYstem comprising: a frequency controllable oscillator; timing means producing timing signals defining a precise predetermined interval of time; a binary counting means, responsive to the oscillator output signal and to the timing means for counting the number of cycles in the oscillator output signal during each predetermined interval of time, and producing a binary signal of one state when said number of cycles is greater than a predetermined number and a binary signal of the opposite state when said number of cycles is less than the predetermined number; a first means for converting said binary signal to an analog signal at the end of each time interval; and a second means coupling the analog signal to said oscillator for increasing or decreasing the frequency thereof in accordance with the binary indication.
Claim 2
Dependent Claim
163 words
An automatic frequency control system wherein the frequency of an oscillator is periodically determined during intervals of time precisely controlled to derive indications of the frequency thereof for controlling said frequency, said sYstem comprising: a frequency controllable oscillator; timing means producing timing signals defining a precise predetermined interval of time; a binary counting means, responsive to the oscillator output signal and to the timing means for counting the number of cycles in the oscillator output signal during each predetermined interval of time, and producing a binary signal of one state when said number of cycles is greater than a predetermined number and a binary signal of the opposite state when said number of cycles is less than the predetermined number; a first means for converting said binary signal to an analog signal at the end of each time interval; and a second means coupling the analog signal to said oscillator for increasing or decreasing the frequency thereof in accordance with the binary indication.
Claim 3
Dependent Claim
46 words
An automatic frequency control system as defined in claim 1 wherein said frequency controllable oscillator is a frequency modulated oscillator having an output circuit, a frequency control input circuit, and a modulating input circuit; said frequency control input circuit capable of varying the output center frequency.
Claim 4
Dependent Claim
46 words
An automatic frequency control system as defined in claim 1 wherein said frequency controllable oscillator is a phase modulated oscillator having an output circuit, a frequency control input circuit, and a modulating input circuit; said frequency control input circuit capable of varying the output center frequency.
Claim 5
Dependent Claim
23 words
An automatic frequency control system as defined in claim 1 wherein said first means comprises a sample-and-hold circuit coupled to an integrator circuit.
Claim 6
Dependent Claim
47 words
An automatic frequency control system as defined in claim 1 wherein said timing means comprises: a frequency stable reference oscillator; and means responsive to said reference oscillator for generating a binary pulse having a pulse width defined by a predetermined number of cycles from said reference oscillator.
Claim 7
Dependent Claim
66 words
An automatic frequency control system as defined in claim 1 wherein said timing means comprises: a frequency stable reference oscillator; and means responsive to said reference oscillator for generating a binary pulse, having a pulse width that is less than the time between binary pulses, and having a precise repetition rate, said repetition rate being defined by a predetermined number of cycles from said reference oscillator.
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) | 1978-06-30 | 1978-12-30 | 1979-07-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-30 | 1982-12-30 | 1983-07-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-30 | 1986-12-30 | 1987-07-01 | $7700.00 | Window Closed / Lapsed |