TABLE OF CONTENTS In this chapter the effect of additional jamming on the performance of clutter filters will be analysed. We assume that the jammers transmit continuously (CW) and are broadband, that is, the jammer bandwidth is larger than the usable Doppler bandwidth. In the numerical analysis the jammer model given in Section 2.4.3 is used. The effect of MTI under jamming conditions has been discussed by the author [246, 255].
There are basically two ways of performing jammer and clutter rejection. One possibility is simultaneous jammer and clutter suppression. This means that during normal radar operation the jamming + clutter space-time covariance matrix is estimated and a space-time filter for rejection of jamming and clutter is designed on the basis of the covariance matrix. The number of degrees of freedom has to be chosen so that the jammer + clutter scenario is adequately covered.
The second possibility is to perform jammer and clutter rejection in two steps (KLEMM [246], FANTE [117]). The first step includes the estimation of a spatial jammer covariance matrix in a passive radar mode, that is, before transmit, to make sure that the covariance matrix estimate is free of clutter. In the second step the jammer + clutter covariance matrix is estimated after transmit and after the spatial anti-jamming filter. The resulting space-time clutter filter has to cope with clutter only if the jammer cancellation is perfect.
Both of these techniques will be analysed in the following sections. Optimum and suboptimum...
