US3713144A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phase signature radar
Assignee: United States Department of the Air Force
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Filing: 1968-11-22
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Granted: 1973-01-23
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Expires: 1988-11-22
Abstract
Abstract A radar method and system of distinguishing radar echoes of discrete and point targets such as moving and motionless aircraft, trucks, etc., from reflections from distributed targets such as the earth''s surface, the radar echoes resulting from a succession of single pulses transmitted from a single antenna. The electrical phase within the returning radar echoes is measured by means of a coherent CW oscillator operating at the frequency of the transmitted radar signal. The measurement of phase as a function of time results in a fixed or stationary phase measurement for point targets distinguishable from the variable phase changes corresponding to distributed or multiple targets.
Inventors
- 👤 C Letten
- 👤 W Goggins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 16:05
CPC Classifications
G; G01; G01S; G01S7/00; G01S7/02; G01S7/41; G01S7/414
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
174 words
A phase signature radar system for identifying moving and motionless point targets from the background thereof comprising means to generate a stable continuous wave signal having a preselected frequency, means to pulse said generated signal, means to transmit the pulsed signal toward said point targets and the background thereof, means to receive return echoes from said point targets and the background thereof, said transmit and receive means being common, means to limit the amplitude of said received return echoes while maintaining the phase thereof to discard completely amplitude variations, an isolating amplifier connected directly to the output of said stable continuous wave signal generating means, phase comparison means receiving directly and simultaneously the output signal from said amplitude limiting means and said isolating amplifier to provide a resultant phase difference signal serving as a phase signature to distinguish said point targets from the background thereof, means to convert said resultant phase signal to a representative voltage signal, and means to filter said representative voltage signals to pass only signals representative of said point targets.
Claim 2
Dependent Claim
174 words
A phase signature radar system for identifying moving and motionless point targets from the background thereof comprising means to generate a stable continuous wave signal having a preselected frequency, means to pulse said generated signal, means to transmit the pulsed signal toward said point targets and the background thereof, means to receive return echoes from said point targets and the background thereof, said transmit and receive means being common, means to limit the amplitude of said received return echoes while maintaining the phase thereof to discard completely amplitude variations, an isolating amplifier connected directly to the output of said stable continuous wave signal generating means, phase comparison means receiving directly and simultaneously the output signal from said amplitude limiting means and said isolating amplifier to provide a resultant phase difference signal serving as a phase signature to distinguish said point targets from the background thereof, means to convert said resultant phase signal to a representative voltage signal, and means to filter said representative voltage signals to pass only signals representative of said point targets.
Claim 3
Dependent Claim
57 words
A phase signature radar system as described in claim 1 further including a broadband receiver interconnected between said common receiving means and said amplitude limiting means, said braodband receiver having a preselected bandwidth approximately equal to 10 X 1/ Tau with Tau being equal to the period of said pulsed signal to preserve the intrapulse phase structure.
Claim 4
Dependent Claim
36 words
A phase signature radar system as described in claim 2 wherein said filter means is limited to a time constant approximately equal to 1/3 Tau with Tau being equal to the period of said pulsed signal.
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) | 1976-01-23 | 1976-07-24 | 1977-01-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-01-23 | 1980-07-24 | 1981-01-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-01-23 | 1984-07-24 | 1985-01-23 | $7700.00 | Window Closed / Lapsed |