Method and apparatus for improved determination of range and angle of arrival utilizing a two tone CW radar
First Claim
1. A method for improving the range and angle of arrival accuracy of a two-tone CW radar from which sum and difference signals for the two frequencies associated with the two tones are available, comprising the steps of:
- forming a first two-by-two matrix from the sum and difference signals for each of the two frequencies associated with the two tones;
factorizing the first two-by-two matrix into a second and third matrix associated respectively with range and angle of arrival; and
,determining range and angle of arrival from the respective two-by-two matrices, whereby all of the information in the sum and difference signals for the two frequencies is used in the determination of range and angle of arrival.
1 Assignment
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Accused Products
Abstract
An improved system is provided for aiming a shotgun-based or other countermeasure system so as to be able to countermeasure incoming rockets or projectiles. In one embodiment a shotgun aimed and controlled by the subject system projects a pattern of pellets to intercept a rocket-propelled grenade or incoming projectile. The fire control system uses a CW two-tone monopulse radar to derive range and angle of arrival within 150 milliseconds, with range and angle of arrival measurements having approximately twice the accuracy of prior CW two-tone monopulse radars. The improvement derives from using all of the information in the returned radar beams and is the result of the recognition that one can use the Sum and Difference signals to assemble a two-by-two Rank One matrix that permits using singular value decomposition techniques to generate range and angle of arrival matrices in which all available information is used and in which noise is eliminated.
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Citations
19 Claims
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1. A method for improving the range and angle of arrival accuracy of a two-tone CW radar from which sum and difference signals for the two frequencies associated with the two tones are available, comprising the steps of:
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forming a first two-by-two matrix from the sum and difference signals for each of the two frequencies associated with the two tones; factorizing the first two-by-two matrix into a second and third matrix associated respectively with range and angle of arrival; and
,determining range and angle of arrival from the respective two-by-two matrices, whereby all of the information in the sum and difference signals for the two frequencies is used in the determination of range and angle of arrival. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A system for determining range and angle of arrival of a target moving relative to a two-tone CW radar from which sum and difference signals for the two frequencies associated with the two tones are available, comprising:
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a down converter for down-converting, low pass filtering and sampling said sum and difference signals; a demultiplexer for providing time domain data streams corresponding to the down-converted, low pass filtered and sampled sum and difference signals; a module coupled to said demultiplexer for performing a Fast Fourier Transform on said time-domain data stream to produce associated frequency domain data streams in the form of individual frequency bins; a calculator for squaring the magnitude of the individual bins to produce magnitude-squared values; an accumulator for accumulating said magnitude-squared values; a peak search detector for determining from the accumulated magnitude-squared values which of said frequency bins has the highest peak, thus to determine which of said frequency bins contains said target; a processor for generating a first two-by-two matrix from the sum and difference values associated with the bin that is determined to contain said target; and
,a unit for performing a singular value decomposition of said first two-by-two matrix so as to factor said first matrix into a second and third matrix respectively related to range and angle of arrival. - View Dependent Claims (9, 10)
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11. Apparatus for determining range and angle of arrival of a target moving relative to a two-tone CW radar from which sum and difference signals for the two frequencies associated with the two tones are available, comprising:
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means for forming frequency bins for said sum and difference signals; a peak detector for determining which of said frequency bins contains said target; a matrix generator for generating a first two-by-two matrix from the sum and difference signals in the frequency bin containing said target; and
,a factoring unit for factoring said first matrix into second and third two-by-two matrices having respective first columns containing information related respectively to the range and angle of arrival of said target, thus to determine the range and angle of arrival of said target. - View Dependent Claims (12)
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13. In a system for countermeasuring a rocket-propelled grenade using a multiple-barrel gun that projects a pattern of shot towards an incoming rocket-propelled grenade, a method for improving the aiming and firing accuracy of the gun, comprising the steps of:
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using a two-tone monopulse CW radar that develops sum and difference signals for deriving the range, angle of arrival and velocity of the rocket-propelled grenade relative to the radar; and
,aiming and firing the gun based on the angle of arrival, range and velocity measurements from the radar. - View Dependent Claims (14, 15, 16, 17, 18, 19)
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Specification