US4321602A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Frequency-tracking filter, as for use in FM-CW radar
Assignee: Lockheed Martin Corp
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Filing: 1980-07-07
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Granted: 1982-03-23
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Expires: 2000-07-07
Abstract
Abstract The performance of a frequency-tracking filter comprising a phase-locked loop synchronized by square-wave output signal from a limiter amplifier is improved during interruptions in that signal by interposing a level discriminator between the limiter amplifier and the phase comparator element of the phase-locked loop.
Inventors
- 👤 Ronald W. Kipp
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 05:44
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/06; G01S13/08; G01S13/32; G01S13/34; G01S13/345
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
127 words
A frequency-tracking filter comprising: means responsive to a signal the frequency of which is to be tracked for symmetrically amplitude-limiting said signal about an average-level axis; a level discriminator coupled to said limiting means to provide discriminator output signals only if said signals depart from said average-level axis by more than a predetermined threshold value; a controlled oscillator generating output signal at a frequency determined by a control signal; means coupled to said discriminator and said oscillator for comparing the phase of said oscillator output signal and the said discriminator output signal to provide a phase-error signal indicative of their phase of difference; and means responsive to only those components of said phase-error signal below a predetermined cut-off frequency for providing said control signal to said oscillator.
Claim 2
Dependent Claim
127 words
A frequency-tracking filter comprising: means responsive to a signal the frequency of which is to be tracked for symmetrically amplitude-limiting said signal about an average-level axis; a level discriminator coupled to said limiting means to provide discriminator output signals only if said signals depart from said average-level axis by more than a predetermined threshold value; a controlled oscillator generating output signal at a frequency determined by a control signal; means coupled to said discriminator and said oscillator for comparing the phase of said oscillator output signal and the said discriminator output signal to provide a phase-error signal indicative of their phase of difference; and means responsive to only those components of said phase-error signal below a predetermined cut-off frequency for providing said control signal to said oscillator.
Claim 3
Dependent Claim
29 words
Apparatus for measuring frequency comprising, in combination, a frequency-tracking filter as set forth in claim 1, and a frequency detector coupled to said oscillator to receive output signals therefrom.
Claim 4
Dependent Claim
81 words
In combination with apparatus for measuring frequency as set forth in claim 2, a frequency modulated continuous-wave radar including: means for transmitting a frequency-modulated carrier wave; means for receiving its reflection from a target; and means for mixing said frequency-modulated wave and its reflection to provide a difference signal indicative of the range of said target; and means for applying said difference signal to said means for symmetrically amplitude limiting, as said signal the frequency of which is to be tracked.
References Cited (Backward Citations)
US4072947A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1985-03-22 | 1985-09-21 | 1986-03-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-03-22 | 1989-09-21 | 1990-03-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-03-22 | 1993-09-21 | 1994-03-23 | $7700.00 | Window Closed / Lapsed |