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US 4,994,810 AGranted
Monopulse processor digital correction circuit
AssigneeAllied-Signal Inc.
InventorAllen I. Sinsky
Life of this patent
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Abstract
A method and correction circuit is described incorporating a monopulse receiver, injecting a first signal of known amplitude and arbitrary phase and a second signal of the same amplitude shifted 90.degree. and measuring the output voltages of the channel and using the measurements to generate four coefficients which may be mathematically applied to the ouptut signals of the channel to provide a corrected output. The invention overcomes the problem of compensating for phase and gain drift in the in-phase and quadrature paths of the sum and difference channels of a monopulse receiver.
Claims8
In a monopulse radar having sum .SIGMA. and difference .DELTA.channels for providing angular measurements of a radar target from the radar,
- said sum channel including a first quadrature detector,
- said difference channel including a second quadrature detector,
- each of said first and second detectors having an in-phase I channel and a quadrature Q channel;
- a method for digital compensation of phase and gain drift in said first and second detectors comprising the steps of:
- first, injecting a first signal of known amplitude and arbitrary phase into both said first and second detectors;
- second, measuring the uncorrected voltage outputs of said in-phase I and quadrature Q channels of said first detector and said second detector to provide values V.sub..SIGMA.I (1) from said in-phase channel of said first detector and V.sub..SIGMA.Q (1) from said quadrature channel of said first detector and V.sub..DELTA.I (1) from said in-phase channel of said second detector and V.sub..DELTA.Q (1) from said quadrature channel of said second detector;
- third, inserting a 90.degree. phase shift in said first signal to provide a second signal;
- fourth, injecting said second signal into both said first and said second detectors;
- fifth, measuring the uncorrected voltage outputs of said in-phase I and quadrature Q channels of said first and second detectors to provide values V.sub..SIGMA.I (2) from said in-phase channel of said first detector and V.sub..SIGMA.Q (2) from quadrature channel of said first detector and V.sub..DELTA.I (2) from said in-phase channel of said second detector and V.sub..DELTA.Q (2) from said quadrature channel of said second detector;
- sixth, computing directly from said values V.sub..SIGMA.I (1), V.sub..SIGMA.Q (1), V.sub..SIGMA.I (2) and V.sub..SIGMA.Q (2) a first set of four correction coefficients K.sub.1, K.sub.2, K.sub.3 and K.sub.4 ;
- seventh, computing directly from said values V.sub..DELTA..sub.I (1), V.sub..DELTA.Q (1), V.sub..DELTA.I (2) and V.sub..DELTA.Q (2) a second set of four correction coefficients K.sub.5, K.sub.6, K.sub.7 and K.sub.8 ;
- eighth, removing said first and second signals from both said first and second quadrature detectors;
- ninth, applying said first set of coefficients to the output signals of said in-phase and quadrature channels of said first detector to provide third and fourth signals having compensation for phase and gain drift;
- and
- tenth, applying said second set of coefficients to the output signals of said in-phase and quadrature channels of said second detector to provide fifth and sixth signals having compensation for phase and gain drift.
12 more elements
In a monopulse radar having sum .SIGMA. and difference .DELTA. channels for providing angular measurements of a radar target from the radar,
- said sum channel including a first quadrature detector,
- said difference channel including a second quadrature detector,
- each of said first and second detectors having an in-phase I channel and a quadrature Q channel;
- a method for digital compensation of phase and gain drift in said first and second detectors comprising the steps of:
- first, injecting a first signal of known amplitude and arbitrary phase into both said first and second detectors;
- second, measuring the uncorrected voltage outputs of said in-phase I and quadrature Q channels of both said first and said second detectors to provide values V.sub..SIGMA.I (1) from said in-phase channel of said first detector and V.sub..SIGMA.Q (1) from said quadrature channel of said first detector and V.sub..DELTA.I (1) from said in-phase channel of said second detector and V.sub..DELTA.Q (1) from said quadrature channel of said second detector;
- third, inserting a 90.degree. phase shift in said first signal to provide a second signal;
- fourth, injecting said second signal into both said first and said second detectors;
- fifth, measuring the uncorrected voltage outputs of said in-phase I and quadrature Q channels of both said first and second detectors to provide values V.sub..SIGMA.I (2) and V.sub..SIGMA.Q (2) from said first detector and V.sub..DELTA.I (2) and V.sub..DELTA.Q (2) from said second detector;
- sixth, computing directly from said values V.sub..SIGMA.I (1), V.sub..SIGMA.Q (1), V.sub..SIGMA.I (2) and V.sub..SIGMA.Q (2) a first set of four correction coefficients K.sub.1, K.sub.2, K.sub.3 and K.sub.4 ;
- seventh, computing directly from said values V.sub..DELTA.I (1), V.sub..DELTA.Q (1), V.sub..DELTA.I (2) and V.sub..DELTA.Q (2) a second set of four correction coefficients K.sub.5, K.sub.6, K.sub.7 and K.sub.8 ;
- eighth, repeating said first, second, third, fourth, fifth, sixth, and seventh steps a plurality of times to provide a plurality of values of said K.sub.1, K.sub.2, K.sub.3 and K.sub.4 of said first set of correction coefficients and K.sub.5, K.sub.6, K.sub.7 and K.sub.8 of said second set of correction coefficients;
- ninth, computing from said plurality of values of K.sub.1, K.sub.2, K.sub.3 and K.sub.4 a third set of correction coefficients K.sub.1 av., K.sub.2 av., K.sub.3 av. and K.sub.4 av., each of said coefficients of said third set comprising the average value of corresponding coefficients of said plurality of values of said first set;
- tenth, computing from said plurality of values of K.sub.5, K.sub.6, K.sub.7 and K.sub.8 a fourth set of correction coefficients K.sub.5 av., K.sub.6 av., K.sub.7 av. and K.sub.8 av., each of said coefficients of said fourth set comprising the average value of corresponding coefficients of said plurality of values of said second set;
- eleventh, removing said first and second signals from both said first and said second detectors;
- twelfth, applying said third set of correction coefficients to the output signals of said in-phase and quadrature channels of said first detector to provide third and fourth signals having compensation for phase gain and drift;
- and
- thirteenth, applying said fourth set of correction coefficients to the output signals of said in-phase and quadrature channels of said second detector to provide fifth and sixth signals having compensation for phase gain and drift.
15 more elements
Dependencies are inferred from the claim text.