Theoretical aspects on a method for terrain scattered interference mitigation in radar

Hot clutter (terrain-scattered interference (TSI), terrain-scattered jamming (TSJ) or jammer multipath) are signals from jammers which are reflected on the ground or sea before they are received by a radar. In the mainbeam an often weak target signal has to compete with hot clutter. Hot clutter is a significant problem today to military airborne radar systems and should be suppressed. This paper is a theoretical analysis of a hot clutter suppression method which consists of 1) estimating the direct jammer signal, 2) estimating the linear system created by the multipath (the "reflection system") and 3) removing an estimate of the reflected jammer signal from the main received radar signal. The paper can give a better understanding of the method and guidance on how to design the method for the best result. The results of the work in this paper are: both with white and colored noise, we can state and solve optimal estimation problems for the reflection system and give expressions for the bias and covariance. We can also see how the model order, the number of data etc. influences the estimation quality.