US5276453A
Expired / Lapsed
US
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Method for ambiguity resolution in range-Doppler measurements
Assignee: National Aeronautics and Space Administration
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Filing: 1993-02-02
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Granted: 1994-01-04
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Expires: 2013-02-02
Abstract
Abstract A method for resolving range and doppler target ambiguities when the target has substantial range or has a high relative velocity in which a first signal is generated and a second signal is also generated which is coherent with the first signal but at a slightly different frequency such that there exists a difference in frequency between these two signals of Δf t . The first and second signals are converted into a dual-frequency pulsed signal, amplified, and the dual-frequency pulsed signal is transmitted towards a target. A reflected dual-frequency signal is received from the target, amplified, and changed to an intermediate dual-frequency signal. The intermediate dual-frequency signal is amplified, with extracting of a shifted difference frequency Δf r from the amplified intermediate dual-frequency signal done by a non-linear detector. The final step is generating two quadrature signals from the difference frequency Δf t and the shifted difference frequency Δf r and processing the two quadrature signals to determine range and doppler information of the target.
Inventors
- 👤 Gerald M. Heymsfield
- 👤 Lee S. Miller
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:41
CPC Classifications
G; G01; G01S; G01S13/00; G01S13/02; G01S13/50; G01S13/58; G01S13/581; G01S13/582; G01S13/06; G01S13/08; G01S13/10; G01S13/30
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
174 words
A method for resolving range and doppler target ambiguities when either substantial range to target exists or a high relative velocity of the target exists comprising the steps of: generating a first signal; generating a second signal which is coherent with said first signal but at a slightly different frequency such that there exists a difference in frequency between these two signals of Δf t ; modulating said first and second signals such that said first and second signals are converted into a dual-frequency pulsed signal; amplifying said dual-frequency pulsed signal; transmitting said dual-frequency pulsed signal towards said target; receiving a reflected dual-frequency signal from said target; amplifying said reflected dual-frequency signal; producing an intermediate dual-frequency signal from said amplified reflected dual-frequency signal; amplifying said intermediate dual-frequency signal; extracting a shifted difference frequency Δf r from said amplified intermediate dual-frequency signal; generating two quadrature signals from said difference frequency Δf t and said shifted difference frequency Δf r ; and processing said two quadrature signals to determine range and doppler information of said target.
Claim 2
Independent Claim
174 words
A method for resolving range and doppler target ambiguities when either substantial range to target exists or a high relative velocity of the target exists comprising the steps of: generating a first signal; generating a second signal which is coherent with said first signal but at a slightly different frequency such that there exists a difference in frequency between these two signals of Δf t ; modulating said first and second signals such that said first and second signals are converted into a dual-frequency pulsed signal; amplifying said dual-frequency pulsed signal; transmitting said dual-frequency pulsed signal towards said target; receiving a reflected dual-frequency signal from said target; amplifying said reflected dual-frequency signal; producing an intermediate dual-frequency signal from said amplified reflected dual-frequency signal; amplifying said intermediate dual-frequency signal; extracting a shifted difference frequency Δf r from said amplified intermediate dual-frequency signal; generating two quadrature signals from said difference frequency Δf t and said shifted difference frequency Δf r ; and processing said two quadrature signals to determine range and doppler information of said target.
Claim 3
Dependent Claim
44 words
The method of claim 1 further comprising the steps of: filtering said amplified reflected dual-frequency signal; producing two intermediate dual-frequency signals from said filtered amplified reflected dual-frequency signal; multiplying said two intermediate dual-frequency signals prior to extracting a shifted difference frequency Δf r .
Claim 4
Independent Claim
193 words
A device for resolving range and doppler target ambiguities when either the device or the target has substantial range or velocity comprising: means for generating a first signal; means for generating a second signal which is coherent with said first signal but at a slightly different frequency such that there exits a difference in frequency between these two signals of Δf t ; means for modulating said first and second signals such that said first and second signals are converted into a dual-frequency pulsed signal; means for amplifying said dual-frequency pulsed signal; antenna means for transmitting said dual-frequency pulsed signal towards said target; means for receiving a reflected dual-frequency signal from said target; means for amplifying said reflected dual-frequency signal; means for producing an intermediate dual-frequency signal from said amplified reflected dual-frequency signal; means for amplifying said intermediate dual-frequency signal; means for extracting a shifted difference frequency Δf r from said amplified intermediate dual-frequency signal; detector means for generating two quadrature signals from said difference frequency Δf t and said shifted difference frequency Δf r ; and means for processing said two quadrature signals to determine range and doppler information of said target.
Claim 5
Independent Claim
193 words
A device for resolving range and doppler target ambiguities when either the device or the target has substantial range or velocity comprising: means for generating a first signal; means for generating a second signal which is coherent with said first signal but at a slightly different frequency such that there exits a difference in frequency between these two signals of Δf t ; means for modulating said first and second signals such that said first and second signals are converted into a dual-frequency pulsed signal; means for amplifying said dual-frequency pulsed signal; antenna means for transmitting said dual-frequency pulsed signal towards said target; means for receiving a reflected dual-frequency signal from said target; means for amplifying said reflected dual-frequency signal; means for producing an intermediate dual-frequency signal from said amplified reflected dual-frequency signal; means for amplifying said intermediate dual-frequency signal; means for extracting a shifted difference frequency Δf r from said amplified intermediate dual-frequency signal; detector means for generating two quadrature signals from said difference frequency Δf t and said shifted difference frequency Δf r ; and means for processing said two quadrature signals to determine range and doppler information of said target.
Claim 6
Dependent Claim
21 words
The device of claim 3 wherein said means for generating said first and second signals comprises a pair of phase-locked oscillators.
Claim 7
Dependent Claim
19 words
The device of claim 3 wherein said means for generating said first and second signals comprises a double-sidebanded modulator.
Claim 8
Dependent Claim
40 words
The device of claim 3 wherein said means for modulating comprises means for producing a dual-frequency pulsed signal having a duration of 1 microsecond and a pulse repetition frequency in the range of 100 pulses to 10,000 pulses per second.
References Cited (Backward Citations)
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