Hughes Electronics Corporation

Raytheon Company

Hughes Aircraft Company

Thomas A Kennedy

Robert A Rosen

Kapriel V Krikorian

Garry N Hulderman

Howard S Nussbaum

Ralston S Robertson

Mark I Landau

Kapriel V Kirkorian

Steve Roth

Methods that compensate for phase errors caused by path length variations in a radar system, and that compensate for relative phase errors in upconvertor and downconverter references employed in the radar system. One method samples a signal reflected from a duplexer through a receiver during the time the radar pulse is transmitted. The signal reflected from the duplexer is compared to a radar echo pulse on a single pulse basis. The phase of the sampled signal is subtracted from the phase of the received radar echo pulse reflected to determine the phase error. In a second method, multiple samples are collected during the time each radar pulse is transmitted. Samples of the signal reflected from the duplexer and the radar echo pulse are compared on a pulse to pulse basis. The phase differences are averaged across the pulse duration. The averaged phase differences are integrated on a pulse to pulse basis to determine the phase error.

Compensation for radar path length variation and phase error

A coherent radar receiver that has pulse-to-pulse coherence using an unlocked voltage controlled oscillator, such as a Gunn voltage controlled oscillator. The present invention is a W-band, for example, bistatic receiver that uses a scanning sum channel antenna to scan the target, a downconverter for downconverting received alternating sum and difference pulse echoes from the bistatic illuminator to provide video signals, and processing circuits for processing the downconverted the video signals to precisely locate the null position on the target. A Fourier transform circuit, magnitude detector and a peak detection and centroid circuit are used to generate a voltage frequency control output signal that is applied to the voltage controlled oscillator or local oscillator that controls its frequency. An angle estimation algorithm is used that processes the video signals to locate the null offset from the center of a scan pattern generated by the antenna. The present invention thus provides for an inexpensive weapon receiver at W-band, for example, using an inexpensive unlocked voltage controlled oscillator. The pulse-to-pulse coherence achieved by the receiver permits precise location of a target of interest from bistatic radar returns.

Unlocked W-band receiver with coherent features

A method wherein the scan rate of an active emitter is simultaneously estimated by a tracking receiver and a radar system and are then compared to correlate tracks generated by the tracking receiver and the radar system. The output produced by the present method provides for data that is more accurately indicative of the locations and identifications of emitters tracked by the tracking receiver and the radar system. More specifically, the method comprises the following steps. An active emitter having a scanning antenna is simultaneously tracked using a tracking receiver and a radar system. The location of the emitter is estimated using the tracking receiver by processing measurements of the electromagnetic signals generated by the emitter. The scan rate of the emitter is estimated using the tracking receiver by detecting strobing of the main lobe of the signals generated the emitter. The scan rate of the emitter is estimated using the radar system. Finally, the respective estimated scan rates are correlated to improve the accuracy of the estimated location and identification of the emitter.

Detecting active emitters using scan rate correlation of tracking

A system and method that provides for all-weather precision guidance of conventional air-to-surface weapons. The system and method employs a coherent monopulse radar disposed on a launch platform and a noncoherent passive (receive only) radar disposed on the weapon. The synthetic aperture radar generates a synthetic aperture radar monopulse map of an area around the target. The radar is used designate the location of the target, and transmit a sequence of alternating sum and simultaneous azimuth and elevation difference patterns centered on the target. The weapon includes a guidance system and seeker that is responsive to guidance commands transmitted by the synthetic aperture radar. The guidance system and seeker receives reflections of the alternating sum and combined azimuth and elevation difference pattern from the target, and the sum pulse is used by the weapon to acquire and track the azimuth and elevation difference pattern null on the target to fly an optimum trajectory to the target. One method for guiding a weapon to a target comprises the following steps. A synthetic aperture radar is used to generate a SAR monopulse map of a target area and designate a target therein. The weapon is then launched toward the target. The radar is used to transmit an interleaved sum and simultaneous azimuth and elevation difference pattern guidance pulse train at the target. The reflected interleaved sum and simultaneous azimuth and elevation difference pattern is received from the target at a seeker and guidance system on the weapon. The sum pattern is used by the weapon to lock onto the converging null, and is used by the launch platform to provide closed loop tracking of the target during guidance illumination. After weapon null lock-on, steering commands are generated to cause the weapon to fly an optimum trajectory to the target.

Combined SAR monopulse and inverse monopulse weapon guidance

Growing community of inventors

Manhattan Beach, CA, United States of America

Thomas A Kennedy