Signal amplitude conditioned density function for monopulse measurements of fixed-amplitude targets

Since the measured amplitude of the sum-signal of a monopulse radar is known in the receiver, the probability density function (PDF) for the monopulse measurements can be conditioned on the measured amplitude. The conditional PDF and related statistical properties are developed for the in-phase and quadrature parts of the monopulse measurements of fixed-amplitude targets. Conditions under which the conditional PDF can be approximated as Gaussian are considered. A decoupling of the estimation of the target amplitude and the monopulse processing is proposed for estimating the direction-of-arrival (DOA) for moderate to low SNR targets. Estimators of the variances of the monopulse measurements and the DOA estimate are also given for use in decision and control algorithms such as target tracking with a Kalman filter