Lockheed Martin Corporation

General Electric Company

Martin Marietta Corporation

Lockheed Martin Corpora Tion

Kai-Bor Yu

David J Murrow

Moayyed A Hussain

Yibin Zheng

Peter G Kaup

Svetlana Monakhova Bachmann

Manuel Francisco Fernandez

Koeunyi Bae

A system and method for increasing the effective angular resolution of a multi-function phased array radar system is provided. The system is operative to simultaneously transmit a plurality of overlapping sub-beams covering a representative central beam. A de-convolution process is applied to received return signals. The process includes determining the reflectivity within sub-beamwidth resolution cells defined by the overlapping sub-beams. Generated sub-beamwidth data provides the radar system with an effective angular resolution beyond that of any single transmitted beam.

Enhanced-resolution phased array radar

A method for determining target angles based on data received from a monopulse radar array antenna includes receiving from a beamformer that generates beams from signals generated by the monopulse radar antenna signals having data indicative of a sum beam, an azimuth difference beam, an elevation difference beam, and a delta-delta beam; based on the received signals, determining by the processor an azimuth monopulse ratio, an elevation monopulse ratio, a first complementary monopulse ratio based on the ratio of the delta-delta beam to the delta elevation beam, and a second complementary monopulse ratio based on the ratio of the delta-delta beam to the delta azimuth beam; determining an azimuth angle by the processor based on the azimuth monopulse ratio and the first complementary monopulse ratio; determining an elevation angle by the processor based on the elevation monopulse ratio and the second complementary monopulse ratio; providing an output signal indicative of the azimuth angle; and providing an output signal indicative of the elevation angle.

Method and system for monopulse radar target angle determination

A method for target detection and angle estimation in a radar system includes receiving a signal from a radar array; based on the received signal, performing monopulse beamforming to obtain one or more monopulse beams; based on the monopulse beams, determining monopulse ratios; using maximum likelihood estimation based on the determined monopulse ratios to determine a monopulse ratio estimate corresponding to a maximum of a likelihood function; accessing a table correlating monopulse ratio estimates and target angle values and determining from the table an estimated target angle; accessing a complex target amplitude corresponding to the estimated target angle, comparing the complex target amplitude to a threshold; and if, based on the step of comparing, the target amplitude exceeds the threshold, providing an output signal indicative of target detection and the estimated target angle.

Method and system for target detection and angle estimation based on a radar signal

An improvement in monopulse radar achieves nulling of a single mainlobe jammer and multiple sidelobe jammers while maintaining the angle measurement accuracy of the monopulse ratio by cascading a multiple sidelobe canceller and a mainlobe canceller, and imposing a mainlobe maintenance technique during the sidelobe jammer cancellation process so that the results of the sidelobe jammer cancellation process do not distort the subsequent mainlobe cancellation process. In this manner, the sidelobe jammers and the mainlobe jammer are cancelled sequentially in separate processes.

Combining sidelobe canceller and mainlobe canceller for adaptive monopulse radar processing

A method, apparatus, and processing system for radar detection and tracking of a target using monopulse ratio processing comprising the following steps. First, receiving a signal comprised of a plurality of sum azimuth beams and difference azimuth beams. Then staggering the received signal. Next, filtering and localizing a clutter signal which is a portion of the received sum and azimuth beams. Then adaptively forming a sub-array sum azimuth beam and a sub-array difference azimuth beam from the filtered output to cancel the clutter. The adaptive beam forming including the determination of a sum and difference beam weight where the adaptive weight be equated to a product of the weight and the respective covariance matrices of the sum and difference beams, the product having no constraint points. Finally, forming a final sum azimuth beam and final difference beam where the first sub array is related to the sum and azimuth beams of a plurality of other sub-array sum and difference beams, an overall final sum beam is formed and is used for target detection. In addition, an overall final difference beam is formed and the ratio of the overall final difference beam to the overall final sum beam is used for angle location determination.

Pri-staggered post-doppler adaptive monopulse processing for detection and location of a moving target in ground clutter

A radar system and technique provide the capability to detect a target of interest and maintain the detection in the presence of multiple mainlobe and sidelobe jamming interference. The system and technique utilize digital beamforming to form sub-arrays for canceling jamming interference. Jamming is adaptively suppressed in the sub-arrays prior to using conventional deterministic methods to form the sum, &Sgr;, and difference, &Dgr;, beams for monopulse processing. The system and technique provide the ability to detect a target of interest, provide an undistorted monopulse ratio, m, and maintain target angle estimation, in the presence of multiple mainlobe and multiple sidelobe jammers.

Adaptive digital sub-array beamforming and deterministic sum and difference beamforming, with jamming cancellation and monopulse ratio preservation

A method and system for are provided for detecting one or more radar targets of interest in the presence of jamming signals. A plurality of sub-arrays are formed from an antenna array. Sub-array beams are adaptively formed so as to point one or more nulls in one or more respective directions corresponding to one or more jammers. A super-resolution technique is applied to determine a count of the one or more radar targets and to determine the corresponding direction of arrival.

Adaptive digital beamforming radar method and system for maintaining multiple source angle super-resolution capability in jamming

In a radar system, sampled aperture data are received from an antenna array. The sampled aperture data include data that do not correspond to echo returns from a beam transmitted by the antenna. A covariance matrix is generating using the sampled aperture data. An eigenvalue decomposition is performed on the covariance matrix. A direction of arrival is determined from which at least one jammer is transmitting a signal included in the sampled aperture data, based on the eigenvalue decomposition.

Digital beamforming radar system and method with super-resolution multiple jammer location

A system identifies a number of targets within a main beam of an antenna array that transmits the main beam and receives echo returns from the main beam. A covariance matrix is generated using the echo returns. The presence of at least one target within a single range cell is detected. A plurality of consecutive pulses are transmitted in a direction of the single range cell within a sufficiently short period that the at least one target remains within the single range cell while the plurality of consecutive pulses are transmitted. An echo signal is sampled from each of the plurality of pulses. An updated covariance matrix is estimated each time the echo signal is sampled. An eigenvalue decomposition is updated each time the covariance matrix is updated. The number of targets in the single range cell is estimated, based on the updated eigenvalue decomposition.

Radar system and method including superresolution raid counting

A radar monopulse signal receiving system according to an aspect of the invention provides sum (&Sgr;) and a single difference (&Dgr;) beam outputs from the beamformer. This is accomplished by encoding the information relating to the azimuth and elevation difference beams onto a single complex number. By comparison with some prior-art arrangements, the number of channels required for processing the signals is reduced. Near the end of the monopulse processing, the quotient is taken of complex number divided by the sum beam information, which directly produces a complex monopulse ratio m&equals;m &plus;jm . The azimuth and elevation monopulse ratios are represented by m and m , respectively.

Monopulse array radar with single difference beam for simultaneous azimuth and elevation angle determination

A method and system for identifying the locations of plural targets lying within a main beam of a monopulse antenna including four ports for generating sum, elevation difference, azimuth difference and double difference signals. The method comprises the steps of forming a monopulse ratio matrix from the sum, elevation difference, azimuth difference and double difference signals; and determining eigenvalues of the monopulse ratio matrix. These eigenvalues are then used to determine the angular locations of the plural targets. Preferably, the eigenvalues are determined by performing an eigenvalue decomposition of the monopulse ratio matrix to generate eigenvalues, and the angles of the targets may be determined from the eigenvalues by the use of a look-up table.

Matrix monopulse ratio radar processor for two target azimuth and elevation angle determination

A method and system for identifying the locations of plural targets lying within the main beam of a monopulse antenna including four ports for generating sum, elevation difference, azimuth difference, and double difference signals. The method comprises the steps of processing the sum, elevation difference, azimuth difference, and double difference signals in accordance with a series of linear equations to obtain a set of intermediate values; and processing the set of intermediate values in accordance with a set of algebraic equations to obtain signals representing an angular direction of each of the plural targets. Preferably, the method further includes the step of processing the sum, elevation difference, azimuth difference and double difference signals and the signals representing the angular directions of the targets according to a further set of algebraic equations to obtain signals representing the amplitude of the beam reflected from each of the targets. Also, in a preferred embodiment, the signals representing the angular direction of the targets include signals representing, for each of the targets, an angular direction of the target in an x-plane, and an angular direction of the target in a y-plane.

Monopulse radar processor for resolving two sources

A monopulse system generates sum (.SIGMA.), elevation difference (.DELTA..sub.EL), azimuth difference (.DELTA..sub.AZ), and double difference (.DELTA..sub..DELTA.) signals, and generates a covariance matrix. The covariance matrix is decomposed to produce at least the principal eigenvector. The location or angular direction within the main beam of a single target is determined from the real component of the quotient of elements of the principal eigenvector, by the use of a look-up table. In another embodiment of the invention, the eigenvalues are generated from the covariance matrix, and the number of significant eigenvalues determines the number of targets within the main beam. If a single target is found, its location is found as described above. If two targets are found in the main beam, the locations of the two targets are determined by a closed-form solution of quadratic equations. A missile using a monopulse radar according to an aspect of the invention determines the presence of two targets within the main beam, which targets may be a real target and a decoy, and uses extrinsic information to identify a selected target as being the true target. The missile is homed in the direction of the selected target.

Monopulse system for target location

A radar or GPS receiving system uses an antenna array to produce multiple antenna beams directed toward multiple targets or spacecraft. Stand-off jammers produce signals which tend to be received on the sidelobes of the antenna beams and to disrupt system operation. An array of autonomous or adaptive nullers process the received signals to produce weights which adjust the antenna nulls to direct them toward the jammers. The antenna nulls of one beam pattern are compared with the nulls of other beam patterns. Normal between-sidelobe nulls will not occur at the same angle on all of the patterns, but those nulls generated by the nullers will occur at the same angle. The directions to the jammers are deemed to be those directions in which all beam patterns have nulls.

Determination of jammer directions using multiple antenna beam patterns

Monopulse radar operation is improved by nulling a single mainlobe jammer and multiple sidelobe jammers while maintaining the angle measurement accuracy of the monopulse ratio. A sidelobe jammer cancelling adaptive array is cascaded with a mainlobe jammer canceller, imposing a mainlobe maintenance technique or constrained adaptation during the sidelobe jammer cancellation process so that results of the sidelobe jammer cancellation process do not distort the subsequent mainlobe jammer cancellation process. The sidelobe jammers and the mainlobe jammer are thus cancelled sequentially in separate processes.

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Niskayuna, NY, United States of America

Kai-Bor Yu