US3764933A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Controlled oscillator system with a time dependent output frequency
Assignee: National Aeronautics and Space Administration
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Filing: 1972-09-27
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Granted: 1973-10-09
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Expires: 1992-09-27
Abstract
Abstract A controlled oscillator system is disclosed for providing an output with a frequency which changes with respect to time and with a phase which is within established phase error limits. The system includes a frequency synthesizer with a symmetrical search oscillator, capable of tuning the output with a range of + OR 100 Hz about any fixed frequency to which the synthesizer is set. For a tuning range of 200 Hz ( + OR - 100 Hz) an expanded search oscillator output of a frequency range of 4 MHz (from 1 MHz to 5 MHz) is provided. A counter counts continuously the expanded output cycles and at each of fixed sampling intervals, e.g., every 0.1 second, the count or number accumulated in the counter is read out. The sample number is compared with a theoretical number which should be present in the counter at the particular sampling instant for proper synthesizer''s output frequency and phase. Any difference between the numbers is used to generate an error signal which controls the input to the search oscillator to adjust the frequency and/or phase of the synthesizer''s output.
Inventors
- 👤 J Fletcher
- 👤 R Winkelstein
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:46
CPC Classifications
H; H03; H03L; H03L7/00; H03L7/02; H03B; H03B23/00; H04; H04B; H04B7/00; H04B7/005; H03B2200/00; H03B2200/006; H03B2200/0092; H03C; H03C3/00; H03C3/02; H03C3/09; H03C3/0908
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
207 words
A controlled oscillator system for providing an output of a frequency which changes with respect to time and with a defined phase, the system comprising: frequency synthesizer means for providing said output, said frequency synthesizer means being settable to a preselected frequency and including a search oscillator for varying the frequency of said output from said preselected frequency over a range of XHz as a function of an input signal applied to said search oscillator; first means for providing an expanded search oscillator output of a frequency variable over a range of yHz, where x and y are integers and y>>x; counter means coupled to said first means for counting each cycle of said expanded search oscillator output; second means for sampling the absolute number in said counter means during each of a succession of sampling instances and for providing for each sampling instant a difference number which is the difference between the actual number in said counter means at the instant of sampling and a theoretical number, representing the number which should be present in said counter means at the sampling instant; and control means responsive to said difference number for controlling the input signal to said search oscillator as a function of said difference number.
Claim 2
Dependent Claim
207 words
A controlled oscillator system for providing an output of a frequency which changes with respect to time and with a defined phase, the system comprising: frequency synthesizer means for providing said output, said frequency synthesizer means being settable to a preselected frequency and including a search oscillator for varying the frequency of said output from said preselected frequency over a range of XHz as a function of an input signal applied to said search oscillator; first means for providing an expanded search oscillator output of a frequency variable over a range of yHz, where x and y are integers and y>>x; counter means coupled to said first means for counting each cycle of said expanded search oscillator output; second means for sampling the absolute number in said counter means during each of a succession of sampling instances and for providing for each sampling instant a difference number which is the difference between the actual number in said counter means at the instant of sampling and a theoretical number, representing the number which should be present in said counter means at the sampling instant; and control means responsive to said difference number for controlling the input signal to said search oscillator as a function of said difference number.
Claim 3
Dependent Claim
113 words
A controlled oscillator system as described in claim 1 wherein said search oscillator is a symmetrical search oscillator for varying said output frequency, definable as fo, from said preselected frequency, definable as fs, to be fo fs - 1/2 x when said search oscillator is at one end of its frequency range and to be fo fs + 1/2 x when said search oscillator is at the other end of its frequency range, said first means providing the expanded output of a frequency, definable as f1, when fo fs - 1/2 x and f2 when fo fs + 1/2 x, f2 - f1 y, and y over x is not less than 100.
Claim 4
Dependent Claim
79 words
A controlled oscillator system as described in claim 1 further including computing means for computing for each sampling instant the theoretical number which should be present in said counter means at said sampling instant as a function of the desired frequency and phase of the synthesizer output at the saMpling instant, said computing means including said second means and filter means for generating a numerical output as a function of at least two-successive difference numbers from said second means.
Claim 5
Dependent Claim
48 words
A controlled oscillator system as described in claim 3 wherein said filter means is a digital filter which generates each numerical output as a function of a present difference number supplied thereto, a preceding difference number supplied thereto and a numerical output previously generated by said digital filter.
Claim 6
Dependent Claim
60 words
A controlled oscillator system as described in claim 1 wherein said control means includes filter means responsive to each difference number for generating a control number, digital-to-analog converter means for converting the control number into an analog error control signal, and integrating means for controlling the input to said search oscillator as a function of the analog error control signal.
Claim 7
Dependent Claim
46 words
A controlled oscillator system as described in claim 5 wherein said filter means is a digital filter providing each control number as a function of the difference number supplied thereto, the preceding difference number supplied thereto and the preceding control number provided by said digital filter.
Claim 8
Dependent Claim
105 words
A controlled oscillator system as described in claim 6 wherein said search oscillator is a symmetrical search oscillator for varying said output frequency definable as fo from said preselected frequency definable as fs to be fo fs - 1/2 x when said search oscillator is at one end of its frequency range and to be fo fs + 1/2 x when said search oscillator is at the other end of its frequency range, said first means providing the expanded output of a frequency definable as f1 when fo fs + 1/2 x, f2 - f1 y and y over x is not less than 100.
Claim 9
Dependent Claim
29 words
A controlled oscillator system as described in claim 7 wherein x is in the range of several hundred Hz and y is in the range of several million Hz.
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 |