Radar system
AssigneeThe United States of America as represented by the Secretary of the Navy
InventorHarry D. Felsenthal, Jr.
Life of this patent
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Abstract
Tracking of a target by a radar possessing electronically controlled nutan (conical scan) is difficult when the target employs pulse jamming techniques, since pulsing of the jammer at or near the nutation frequency causes the radar to break lock on the target. In the present concept, the lobing reference signals for azimuth and elevation are periodically reversed in phase, the reversals of the two signals bearing a quadrature relationship to one another. By thus reversing the direction of nutation in synchronism with the radar pulse-rate switching signal, the deleterious effects of countermeasures on the radar's angle-tracking capabilities are minimized.
Claims3
In a radar of the type possessing an electronically nutated antenna from the output of which azimuth and elevation difference signals are obtained and applied to a modulator for development of a suppressed-carrier wave which is amplitude-modulated at the nutation frequency and which has an amplitude and phase proportional to the amplitude and direction of antenna boresight error, and in which a lobing reference signal generator develops an elevation lobing reference signal and an azimuth lobing reference signal for application to said modulator and also for respective application to two phase-sensitive detectors in order to generate a pair of antenna error signals, the improvement which comprises
- apparatus for improving the target-tracking capabilities of said radar in a pulse-jamming environment, where said pulse jamming is at or near the antenna nutation frequency,
- said apparatus including means for periodically reversing the phase of the said two lobing reference signals so as to minimize the effect of any jamming energy which may be present in the return signal from the target,
- wherein said means for periodically reversing the phase of the said two lobing reference signals including means for developing a pair of rectangular commutating waves 90.degree. out of phase with one another, a pair of phase reversers, means for applying to the other of said phase reversers said azimuth lobing reference signal and the other of said commutating waves, means for applying the output of said one phase reverser both to said modulator and to one of said phase-sensitive detectors, and means for applying the output of the other of said phase reversers both to said modulator and to the remaining one of said phase-sensitive detectors.
Dependencies are inferred from the claim text.