US3715751A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Digital speed gate for doppler radar
Assignee: Raytheon Co
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Filing: 1970-09-30
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Granted: 1973-02-06
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Expires: 1990-09-30
Abstract
Abstract A speed gate for a pulse Doppler or CW Doppler radar wherein a signal being tracked is fed, along with a signal from a digitally controlled oscillator, to an exclusive OR gate ro derive gating signals for clock pulses. such gated clock signals are then used to actuate an up-down counter to derive a digital number indicative of the average phase difference between the signal being tracked and the digitally controlled oscillator. Such number is combined with a digital number indicative of the phase difference, measured by the gated clock signals over a relatively short period, between the signal being tracked and the signal out of the digitally controlled oscillator to produce a digital correction signal for the digitally controlled oscillator to change the phase thereof until a phase lock condition occurs between the signals into the exclusive OR gate.
Inventors
- 👤 G Mead
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 02:12
CPC Classifications
H; H03; H03L; H03L7/00; G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/58; G01S13/585; G01S13/586; Y; Y10; Y10S; Y10S331/00; Y10S331/02
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
133 words
For use in the receiver of a Doppler radar, frequency tracking circuitry for locking the output signal of a digitally controlled oscillator with an echo signal from a selected target, such echo signal being amplitude limited, such circuitry comprising: a. an exclusive OR gate, responsive to the output signal and to the echo signal, for producing a square wAve signal, the degree of asymmetry thereof being indicative of the difference in a frequency between the two applied signals; b. means for producing a digital correction signal proportional to the degree of asymmetry of the square wave signal; and, c. means, responsive to the digital correction signal, for changing the frequency of the output signal of the digitally controlled oscillator to reduce the degree of asymmetry of the square wave signal to a minimum.
Claim 2
Dependent Claim
133 words
For use in the receiver of a Doppler radar, frequency tracking circuitry for locking the output signal of a digitally controlled oscillator with an echo signal from a selected target, such echo signal being amplitude limited, such circuitry comprising: a. an exclusive OR gate, responsive to the output signal and to the echo signal, for producing a square wAve signal, the degree of asymmetry thereof being indicative of the difference in a frequency between the two applied signals; b. means for producing a digital correction signal proportional to the degree of asymmetry of the square wave signal; and, c. means, responsive to the digital correction signal, for changing the frequency of the output signal of the digitally controlled oscillator to reduce the degree of asymmetry of the square wave signal to a minimum.
Claim 3
Dependent Claim
133 words
For use in the receiver of a Doppler radar, frequency tracking circuitry for locking the output signal of a digitally controlled oscillator with an echo signal from a selected target, such echo signal being amplitude limited, such circuitry comprising: a. an exclusive OR gate, responsive to the output signal and to the echo signal, for producing a square wAve signal, the degree of asymmetry thereof being indicative of the difference in a frequency between the two applied signals; b. means for producing a digital correction signal proportional to the degree of asymmetry of the square wave signal; and, c. means, responsive to the digital correction signal, for changing the frequency of the output signal of the digitally controlled oscillator to reduce the degree of asymmetry of the square wave signal to a minimum.
Claim 4
Dependent Claim
133 words
For use in the receiver of a Doppler radar, frequency tracking circuitry for locking the output signal of a digitally controlled oscillator with an echo signal from a selected target, such echo signal being amplitude limited, such circuitry comprising: a. an exclusive OR gate, responsive to the output signal and to the echo signal, for producing a square wAve signal, the degree of asymmetry thereof being indicative of the difference in a frequency between the two applied signals; b. means for producing a digital correction signal proportional to the degree of asymmetry of the square wave signal; and, c. means, responsive to the digital correction signal, for changing the frequency of the output signal of the digitally controlled oscillator to reduce the degree of asymmetry of the square wave signal to a minimum.
Claim 5
Dependent Claim
158 words
Frequency tracking circuitry as in claim 1 wherein the first-named means includes: a. a clock pulse generator for producing clock pulses at the Nyquist rate for the echo signal having the highest frequency; b. first and second gating means, enabled during mutually exclusive periods of time during each reception time of an echo signal by the square wave signal for passing clock pulses; c. a binary up-down counter, responsive to the clock pulses passed by the first and the second gating means, for counting the difference between the number of clock pulses passed by the first gating means and the number of clock pulses passed by the second gating means to derive an average difference count during a plurality of reception times; and, d. a binary adder, responsive to the average difference count in the binary up-down counter and to the clock pulses passed by the first and the second gating means, for producing the digital correction signal.
Claim 6
Dependent Claim
62 words
Frequency tracking circuitry as in claim 2 having, additionally: a. means, responsive to the output signal of the digitally controlled oscillator, for producing a digital indicating signal corresponding to the digital correction signal but displaced in phase therefrom by 90*; and, b. means, responsive to the digital indicating signal and to the echo signal, for indicating when the two are in phase.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-02-06 | 1976-08-07 | 1977-02-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-02-06 | 1980-08-07 | 1981-02-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-02-06 | 1984-08-07 | 1985-02-06 | $7700.00 | Window Closed / Lapsed |