Radar return signal processing method
First Claim
1. A method for distinguishing targets from active clutter and from passive clutter in a radar system, said method comprising the steps of:
- forming a range-Doppler map from a return signal generated by a radar receiver, said map having a multiplicity of map cells wherein each map cell characterizes an amplitude component of said return signal at one of a plurality of range gates and one of a plurality of Doppler bins;
forming a list of potential targets from said map, said list identifying subject map cells whose amplitudes exceed a threshold value;
evaluating amplitudes of said subject cells against amplitudes of selected ones of said map cells to identify subject cells whose amplitudes are likely to have resulted from passive clutter; and
said evaluating step comprises, for each Doppler bin of said map, the step of comparing amplitudes of said subject cells with peak amplitudes for the Doppler bins within which said subject cells reside.
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Accused Products
Abstract
A radar system (10) forms a range-Doppler map (28). A CFAR processor (57) determines a threshold (60) and evaluates the map (28) to identify potential targets whose amplitudes are greater than the threshold. The potential targets are evaluated to determine (88) whether they form substantial peaks for the Doppler bins (32) where they are located, and to determine (98) whether they resemble noise more than targets. In addition, the potential targets are evaluated to determine (114) whether they are most likely the result of range sidelobes and to determine (118) whether they are most likely images of targets rather than targets. When any of these situations are detected, the potential targets are removed from a potential target list (50).
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Citations
28 Claims
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1. A method for distinguishing targets from active clutter and from passive clutter in a radar system, said method comprising the steps of:
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forming a range-Doppler map from a return signal generated by a radar receiver, said map having a multiplicity of map cells wherein each map cell characterizes an amplitude component of said return signal at one of a plurality of range gates and one of a plurality of Doppler bins; forming a list of potential targets from said map, said list identifying subject map cells whose amplitudes exceed a threshold value; evaluating amplitudes of said subject cells against amplitudes of selected ones of said map cells to identify subject cells whose amplitudes are likely to have resulted from passive clutter; and said evaluating step comprises, for each Doppler bin of said map, the step of comparing amplitudes of said subject cells with peak amplitudes for the Doppler bins within which said subject cells reside. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method for distinguishing targets from active clutter and from passive clutter in a radar system, said method comprising the steps of:
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forming a range-Doppler map from a return signal generated by a radar receiver, said map having a multiplicity of map cells wherein each map cell characterizes an amplitude component of said return signal at one of a plurality of range gates and one of a plurality of Doppler bins; forming a list of potential targets from said map, said list identifying subject cells whose amplitudes exceed a threshold value; comparing, for each subject cell, amplitude of said subject cell with a peak amplitude for the Doppler bin within which said subject cell resides; determining, for each subject cell, whether the sum of the amplitude of said subject cell and the amplitude of a cell adjacent in said map to said subject cell at the same range gate as said subject cell does not exceed said threshold value by a predetermined amount; adjusting said list to remove subject cells in response to said comparing and determining steps; and indicating that targets reside at the cells identified by said list after said adjusting step. - View Dependent Claims (15, 16, 17, 18)
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19. A method for distinguishing targets from active clutter and from passive clutter in a radar system, said method comprising the steps of:
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forming a range-Doppler map from a return signal generated by a radar receiver, said map having a multiplicity of map cells wherein each map cell characterizes an amplitude component of said return signal at one of a plurality of range gates and one of a plurality of Doppler bins; forming a list of potential targets from said map, said list identifying subject cells whose amplitudes exceed a threshold value; comparing, for each subject cell, amplitude of said subject cell with a peak amplitude for the Doppler bin within which said subject cell resides; determining, for each subject cell, whether the amplitude of said subject cell is less than the amplitude of a map cell that resides substantially in the same range gate for said subject cell but in a Doppler bin where a target image for said subject cell could appear; adjusting said list to remove subject cells in response to said comparing and determining steps; and indicating that targets reside at the cells identified by said list after said adjusting step. - View Dependent Claims (20, 21, 22)
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23. A method for distinguishing targets from active clutter and from passive clutter in a radar system, said method comprising the steps of:
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forming a range-Doppler map from a return signal generated by a radar receiver, said map having a multiplicity of map cells wherein each map cell characterizes an amplitude component of said return signal at one of a plurality of range gates and one of a plurality of Doppler bins; forming a list of potential targets from said map, said list identifying subject cells whose amplitudes exceed a threshold value; determining, for each subject cell, whether the sum of the amplitude of said subject cell and the amplitude of a cell adjacent in said map to said subject cell at the same range gate as said subject cell does not exceed said threshold value by a predetermined amount; evaluating, for each subject cell, whether the amplitude of said subject cell is less than the amplitude of a map cell that resides substantially in the same range gate for said subject cell but in a Doppler bin where a target image for said subject cell could appear; adjusting said list to remove subject cells in response to said determining and evaluating steps; and indicating that targets reside at the cells identified by said list after said adjusting step. - View Dependent Claims (24, 25, 26, 27)
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28. A method for distinguishing targets from active clutter and from passive clutter in a radar system, said method comprising the steps of:
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forming a range-Doppler map from a return signal generated by a radar receiver, said map having a multiplicity of map cells wherein each map cell characterizes an amplitude component of said return signal at one of a plurality of range cells and one of a plurality of Doppler bins; forming a list of potential targets from said map, said list identifying subject cells whose amplitudes exceed a threshold value; comparing, for each subject cell, amplitude of said subject cell with a peak amplitude for the range cell within which said subject cell resides; determining, for each subject cell, whether the sum of the amplitude of said subject cell and the amplitude of a cell adjacent in said map to said subject cell at the same Doppler bin as said subject cell does not exceed said threshold value by a predetermined amount; adjusting said list to remove subject cells in response to said comparing and determining steps; and indicating that targets reside at the cells identified by said list after said adjusting step.
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Specification