Modeling and mitigation of terrain scattered interference

This paper addresses issues concerning terrain scattered interference (TSI) or hot clutter. TSI poses a unique adaptive signal processing problem because of the mainbeam interference which cannot be cancelled by adding more spatial degrees of freedom, and because of Doppler effects that result in time dependent covariance matrix which lead to time varying weights and time dependent signal-to-interference plus noise ratio (SINR). Earlier efforts on TSI mitigation such as the work of Brennan et al. (1982) have described TSI as a linear combination of weighted and delayed replicas of a jammer waveform. The obvious solution is to reverse TSI formation process by employing a tap delay line filter (a finite impulse response filter) whose coefficients are chosen according to an adaptive algorithm.