US 4,789,861 AGranted

Method and apparatus for detecting an out of beam condition in a monopulse radar receiver

AssigneeHughes Aircraft Company

InventorsDon W. Baggett, Jay G. Herther, Deborah E. Bassham

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Abstract

There are derived from the sum and difference signals of a monopulse radar receiver a pair of signatures that quickly and reliably, e.g., unambiguously, indicates when a target being tracked moves out of the center of the antenna main beam. The sum and difference signals are combined in phase quadrature to form a first vector signature signal. The sum and difference signals are also combined in phase quadrature to form a second vector signature signal so that the phase difference between the signature signals varies with the amplitude of the difference signal. The first and second signatures are compared to detect the phase difference therebetween. Commutated signatures are used to determine the direction of target displacement from the antenna boresight and/or to verify the accuracy of the out of beam indication.

Claims23

Dependent claims

A method for detecting an out of beam condition in a monopulse radar receiver comprising the steps of:

forming sum and difference signals from a target return signal;
combining the sum and difference signals to form a first vector signature signal;
combining the sum and difference signals to form a second vector signature signal so that the phase difference between the first and second signature signals varies with the amplitude of the difference signal;
comparing the first and second signature signals to detect the phase difference therebetween;
combining the sum and difference signals to form a third vector signature signal in which the difference signal is of opposite phase to the difference signal of the first signature signal;
combining the sum and difference signals to form a fourth vector signature signal in which the difference signal is of opposite phase to the difference signal of the second signature signal, the phase difference between the third and fourth signature signals varying with the amplitude of the difference signal;
and
comparing the third and fourth signature signals to detect the phase difference therebetween.

5 more elements

A monpulse radar receiver comprising;

means for forming sum and difference signals from a target return signal;
means for combining the sum and difference signals in phase quadrature to form a first vector signature signal;
means for combining the sum and difference signals in phase quadrature to form a second vector signature signal so that the phase difference between the first and second signature signals varies with the amplitude of the difference signal;
means for comparing the first and second signature signals to detect the phase difference therebetween;
means for combining the sum and difference signals in phase quadrature to form a third vector signature signal in which the difference signal is of opposite phase to the difference signal of the first signature signal;
means for combining the sum and difference signals in phase quadrature to form a fourth vector signature signal in which the difference signal is of opposite phase to the difference signal of the second signature signal, the phase difference between the third and fourth signature signals varying with the amplitude of the difference signal;
and
means for comparing the third and fourth signature signals to detect the phase difference therebetween.

5 more elements

Dependencies are inferred from the claim text.