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US4513259A
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Closed loop temperature compensated frequency reference
Assignee: Boeing North American Inc
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Filing: 1982-12-23
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Granted: 1985-04-23
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Expires: 2002-12-23
Abstract
Abstract A closed loop frequency source includes a controllable oscillator that provides a first frequency source, a reference oscillator that provides a second signal, and a comparator that compares the two frequencies to provide an error signal that represents the difference between the frequencies. The error signal is used by an error signal generator to generate a compensation signal which offsets the carrier frequency that drives an output device such as a time-of-day clock so that the output device automatically gains or loses the previously accumulated time error without the necessity of being periodically updated.
Inventors
- 👤 Marvin E. Frerking
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 15:38
CPC Classifications
H; H03; H03L; H03L1/00; H03L1/02; H03L1/022; H03L1/026
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
169 words
A closed loop frequency reference comprising: controllable oscillator means for generating a first frequency signal in response to a control signal; reference oscillator means for generating a second frequency signal; comparator means for comparing the first frequency signal with the second frequency signal to obtain a composite signal; and error signal generator means for generating the control signal during a selected period of time, said error signal generator means including: frequency averaging means for averaging the first frequency signal between a preceding sample time and a current sample time representing a sample interval; first accumulator means for accumulating frequency error up to the current sample time; divisor means for obtaining a quotient of the accumulated frequency error over the sample interval; summing means for summing the quotient with the averaged first frequency to obtain a weighted frequency error; and subtractor means for subtracting the weighted frequency error from a previous correction factor to produce a new correction factor at the output of the subtractor means as the control signal.
Claim 2
Dependent Claim
169 words
A closed loop frequency reference comprising: controllable oscillator means for generating a first frequency signal in response to a control signal; reference oscillator means for generating a second frequency signal; comparator means for comparing the first frequency signal with the second frequency signal to obtain a composite signal; and error signal generator means for generating the control signal during a selected period of time, said error signal generator means including: frequency averaging means for averaging the first frequency signal between a preceding sample time and a current sample time representing a sample interval; first accumulator means for accumulating frequency error up to the current sample time; divisor means for obtaining a quotient of the accumulated frequency error over the sample interval; summing means for summing the quotient with the averaged first frequency to obtain a weighted frequency error; and subtractor means for subtracting the weighted frequency error from a previous correction factor to produce a new correction factor at the output of the subtractor means as the control signal.
Claim 3
Dependent Claim
62 words
The closed loop frequency reference according to claim 1 further comprising: sensor means for measuring the temperature of the reference oscillator means and to provide a temperature signal representative of the measured temperature; and combiner means for combining the temperature signal with the control signal to obtain a temperature compensated control signal to which the first frequency signal generating means will respond.
Claim 4
Dependent Claim
40 words
A closed loop temperature compensated frequency reference according to claim 2, wherein the sensor means comprises: a thermister mounted in close thermal proximity to the means for generating the second frequency; and means for digitizing the output of the thermister.
Claim 5
Dependent Claim
28 words
The closed loop temperature compensated frequency reference according to claim 3, wherein the sensor means comprises: a crystal oscillator whose frequency changes at a known rate with temperature.
Claim 6
Dependent Claim
21 words
The closed loop temperature compensated frequency reference according to claim 2, wherein the controllable oscillator means comprises: a variable frequency oscillator.
Claim 7
Independent Claim
133 words
A method for providing a closed loop frequency reference comprising: generating a first frequency signal in response to a control signal; generating a second frequency signal with a reference oscillator; comparing the first frequency signal with the second frequency signal to obtain a composite signal; and generating the control signal during a selected period of time by: averaging the first frequency between a preceding sample time and a current sample time which represent a sample interval; accumulating a frequency error up to the current sample time; obtaining a quotient of the accumulated frequency error over the sample interval; summing the quotient with the averaged first frequency to obtain a weighted frequency error; and subtracting the weighted frequency error from a previous correction factor to produce a new correction factor as the control signal.
Claim 8
Independent Claim
133 words
A method for providing a closed loop frequency reference comprising: generating a first frequency signal in response to a control signal; generating a second frequency signal with a reference oscillator; comparing the first frequency signal with the second frequency signal to obtain a composite signal; and generating the control signal during a selected period of time by: averaging the first frequency between a preceding sample time and a current sample time which represent a sample interval; accumulating a frequency error up to the current sample time; obtaining a quotient of the accumulated frequency error over the sample interval; summing the quotient with the averaged first frequency to obtain a weighted frequency error; and subtracting the weighted frequency error from a previous correction factor to produce a new correction factor as the control signal.
Claim 9
Dependent Claim
52 words
The method according to claim 6 further comprising the steps of: measuring the temperature of the reference oscillator to provide a temperature signal representative of the measured temperature; and combining the temperature signal with the control signal to obtain a temperature compensated control signal to which the first frequency signal will respond.
Claim 10
Dependent Claim
78 words
A frequency control system comprising: means for generating a first frequency signal in response to a control signal; means for generating a reference frequency; means for comparing said first frequency with said reference frequency to provide an output signal; and means for generating said control signal in response to said output signal during a selected period of time to produce a control signal represented by the difference between a previous correction signal and a current frequency error signal.
Claim 11
Dependent Claim
78 words
A frequency control system comprising: means for generating a first frequency signal in response to a control signal; means for generating a reference frequency; means for comparing said first frequency with said reference frequency to provide an output signal; and means for generating said control signal in response to said output signal during a selected period of time to produce a control signal represented by the difference between a previous correction signal and a current frequency error signal.
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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) | 1988-04-22 | 1988-10-22 | 1989-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-04-22 | 1992-10-22 | 1993-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-04-22 | 1996-10-22 | 1997-04-23 | $7700.00 | Window Closed / Lapsed |