Beam phase modulation for improved synthetic aperture detection and estimation
First Claim
1. A synthetic aperture system comprising:
- array elements (110) configured to transmit energy and receive energy;
a transmitter coupled with said array elements (110) wherein said transmitter comprisesa second transmit multiplier (113) coupled with said array elements (110);
a transmit complex factor (115) coupled with said second transmit multiplier (113);
a first transmit multiplier (112) coupled with said second transmit multiplier (113);
a transmit complex shading weight (114) coupled with said first transmit multiplier (112);
a signal generator (111) comprising an output that is coupled with said first transmit multiplier (112) wherein said output is multiplied by said transmit complex shading weight (114) with said first transmit multiplier (112) which is further multiplied by said transmit complex factor (115) with said second transmit multiplier (113) which results in said transmit energy at said array elements (110);
a receiver coupled with said array elements (110) wherein said receiver comprisesa first receive multiplier (117) coupled with said array elements (110);
a receive complex factor (115) coupled with said first receive multiplier (117);
a second receive multiplier (118) coupled with said first receive multiplier (117);
a receive complex shading weight (116) coupled with said second receive multiplier (118);
a sum operator (119) coupled with said second receive multiplier (118) wherein said receive energy from said array elements (110) is multiplied by said receive complex factor (115) with said first receive multiplier (117) which is further multiplied by said receive complex shading weight (116) with said second receive multiplier (118) and summed with said sum operator (119);
wherein said transmit complex shading weight (114) and said receive complex shading weight (116) are configured to nonlinear phase variation as an observer moves across the transmit energy in one or more direction and wherein said nonlinear phase variation is independent of element phase shifts utilized to steer a beam and independent of phase corrections necessitated by a non-homogeneous propagation environment.
1 Assignment
0 Petitions
Accused Products
Abstract
Phase modulated beam patterns are substituted for the constant-phase versions that have been used in prior synthetic aperture systems. Relative movement between a radar/sonar/ultrasound platform and a point target causes a sequence of echoes from the point target to be phase and amplitude modulated by the beam pattern, as well as by the usual quadratic phase variation caused by range changes. Azimuth, range rate, and azimuth rate estimation, as well as detection in clutter, are substantially improved by appropriate beam pattern phase modulation, which is applied to the transmitter and/or receiver beam patterns. Phase modulated beam patterns are synthesized with array element weighting functions that are designed for high ambiguity function peak-to-sidelobe level, reduction of unwanted ambiguity ridge lines, and adequate spatial sampling. Two dimensional beam pattern phase modulation is useful when the relative motion between a transmit-receive array and multiple targets has both azimuth and elevation components.
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Citations
5 Claims
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1. A synthetic aperture system comprising:
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array elements (110) configured to transmit energy and receive energy; a transmitter coupled with said array elements (110) wherein said transmitter comprises a second transmit multiplier (113) coupled with said array elements (110); a transmit complex factor (115) coupled with said second transmit multiplier (113); a first transmit multiplier (112) coupled with said second transmit multiplier (113); a transmit complex shading weight (114) coupled with said first transmit multiplier (112); a signal generator (111) comprising an output that is coupled with said first transmit multiplier (112) wherein said output is multiplied by said transmit complex shading weight (114) with said first transmit multiplier (112) which is further multiplied by said transmit complex factor (115) with said second transmit multiplier (113) which results in said transmit energy at said array elements (110); a receiver coupled with said array elements (110) wherein said receiver comprises a first receive multiplier (117) coupled with said array elements (110); a receive complex factor (115) coupled with said first receive multiplier (117); a second receive multiplier (118) coupled with said first receive multiplier (117); a receive complex shading weight (116) coupled with said second receive multiplier (118); a sum operator (119) coupled with said second receive multiplier (118) wherein said receive energy from said array elements (110) is multiplied by said receive complex factor (115) with said first receive multiplier (117) which is further multiplied by said receive complex shading weight (116) with said second receive multiplier (118) and summed with said sum operator (119); wherein said transmit complex shading weight (114) and said receive complex shading weight (116) are configured to nonlinear phase variation as an observer moves across the transmit energy in one or more direction and wherein said nonlinear phase variation is independent of element phase shifts utilized to steer a beam and independent of phase corrections necessitated by a non-homogeneous propagation environment. - View Dependent Claims (2, 3, 4, 5)
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Specification