Inverse precision velocity update for monopulse calibration
First Claim
1. A method for estimating an actual boresight of a radar monopulse antenna mounted on a moving platform from Σ
- data and Δ
data generated with respect to a calibrated boresight of said monopulse antenna, said Σ
data generated from a Σ
channel, said Δ
data generated from a Δ
channel, said monopulse antenna coupled to a ground position measuring system, said ground positioning measuring system reporting a position of said monopulse antenna with respect to a reference and a velocity with respect to said reference, said method comprising the steps of;
acquiring a Σ
synthetic aperture map of a radar scattering location, using said Σ
channel of said monopulse antenna with respect to said calibrated boresight, said radar scattering location centered about said calibrated boresight, said Σ
synthetic aperture map formed from Σ
data;
acquiring a Δ
synthetic aperture map of said radar scattering location using said Δ
channel of said monopulse antenna with respect to said calibrated boresight, said Δ
synthetic aperture map formed from a data;
is motion compensating said Σ
data with respect to said reference using said position and said velocity to obtain aligned Σ
pixels;
motion compensating said Δ
data with respect to said reference using said position and said velocity to obtain aligned Δ
pixels, each of said aligned Δ
pixels matched to corresponding said aligned Σ
pixels obtained from said radar scattering location;
forming a ratio of said aligned Δ
pixels to said aligned Σ
pixels for each of a plurality of said aligned Σ
pixels located near said calibrated boresight;
identifying the location of said actual boresight of said monopulse antenna by an analysis of said ratio for a plurality of said aligned Σ
pixels and corresponding said aligned Δ
pixels over said radar scattering location.
1 Assignment
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Accused Products
Abstract
A radar system derives a correction for an actual boresight (311) of a radar monopulse antenna mounted on a moving platform from Σ data and Δ data generated with respect to an a priori known, calibrated boresight (309). The monopulse antenna (602) is coupled to a ground position measuring system (616) while acquiring data. The radar receiver acquires a Σ and Δ synthetic aperture map of the same radar scattering location with respect to the calibrated boresight. Σ SAR data and the Δ SAR data are motion compensated using the position and velocity supplied by the ground positioning system. A computer forms a ratio of the aligned Δ pixels to the aligned Σ pixels for each of a plurality of aligned Σ pixels located near the calibrated boresight. The correction for the location of the actual boresight of the monopulse antenna is computed by an analysis of the ratio of aligned Σ pixels and corresponding aligned Δ pixels over the radar scattering location. Typically, a least square fit analysis is used to plot the Δ/Σ ratio, and ascertain where the zero crossing of the monopulse angle=0 line is found thereby identifying the position of the actual boresight, and the correction from the a priori, calibrated boresight.
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Citations
12 Claims
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1. A method for estimating an actual boresight of a radar monopulse antenna mounted on a moving platform from Σ
- data and Δ
data generated with respect to a calibrated boresight of said monopulse antenna, said Σ
data generated from a Σ
channel, said Δ
data generated from a Δ
channel, said monopulse antenna coupled to a ground position measuring system, said ground positioning measuring system reporting a position of said monopulse antenna with respect to a reference and a velocity with respect to said reference, said method comprising the steps of;acquiring a Σ
synthetic aperture map of a radar scattering location, using said Σ
channel of said monopulse antenna with respect to said calibrated boresight, said radar scattering location centered about said calibrated boresight, said Σ
synthetic aperture map formed from Σ
data;
acquiring a Δ
synthetic aperture map of said radar scattering location using said Δ
channel of said monopulse antenna with respect to said calibrated boresight, said Δ
synthetic aperture map formed from a data;
is motion compensating said Σ
data with respect to said reference using said position and said velocity to obtain aligned Σ
pixels;
motion compensating said Δ
data with respect to said reference using said position and said velocity to obtain aligned Δ
pixels, each of said aligned Δ
pixels matched to corresponding said aligned Σ
pixels obtained from said radar scattering location;
forming a ratio of said aligned Δ
pixels to said aligned Σ
pixels for each of a plurality of said aligned Σ
pixels located near said calibrated boresight;
identifying the location of said actual boresight of said monopulse antenna by an analysis of said ratio for a plurality of said aligned Σ
pixels and corresponding said aligned Δ
pixels over said radar scattering location. - View Dependent Claims (2, 3, 4, 5, 6)
- data and Δ
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7. A radar system deriving a correction for an actual boresight of a radar monopulse antenna mounted on a moving platform from Σ
- data and Δ
data generated with respect to a calibrated boresight of said monopulse antenna, said Σ
data generated from a Σ
channel, said Δ
data generated from a Δ
channel, said monopulse antenna coupled to a ground position measuring system, said ground positioning measuring system reporting a position of said monopulse antenna with respect to a reference and a velocity with respect to said reference, said radar system comprising;a radar receiver for acquiring a Σ
synthetic aperture map of a radar scattering location using said Σ
channel of said monopulse antenna, and a Δ
synthetic aperture map of said radar scattering location using said Δ
channel of said monopulse antenna, said Σ
synthetic aperture map and said Δ
synthetic aperture map acquired with respect to said calibrated boresight, said Σ
synthetic aperture map formed from Σ
data, said Δ
synthetic aperture map formed from Δ
data;
motion compensator using said ground position measuring system for motion compensating said Σ
data with respect to said reference and said Δ
data with respect to said reference using said position and said velocity to obtain aligned Σ
pixels and aligned Δ
pixels;
computer for forming a ratio of said aligned Δ
pixels to said aligned Σ
pixels for each of a plurality of said aligned Σ
pixels located near said calibrated boresight;
said computer also computing said correction for the location of said actual boresight of said monopulse antenna by an analysis of said ratio for a plurality of said aligned Σ
pixels and corresponding said aligned Δ
pixels over said radar scattering location. - View Dependent Claims (8, 9, 10, 11, 12)
- data and Δ
Specification