Exploiting robust direct data domain STAP for GMTI in very high resolution SAR

In this paper we exploit the robust direct data domain STAP (RD³-STAP) in the SAR case. This is extremely interesting especially for very high resolution SAR systems. In fact, in this case due to the strong heterogeneous characteristics of the clutter over range, stochastic STAP might fail due to the possible lack of enough homogeneous secondary data for adequate clutter covariance matrix estimation. In the proposed approach, the RD³-STAP filter is applied in the Doppler domain independently for every different Doppler bin, leading to a factorization of the space-time cancellation problem into independent space only cancellation sub-problems. The different spectral clutter components decoupling resulting from long SAR coherent processing intervals ensures that clutter cancellation capabilities are not reduced by this factorization. A nice property of the RD³-STAP filter ensures together with the clutter cancellation also a compensation of the moving target phase history. A possible integration of the RD³-STAP with the remainder SAR processing is presented and finally the effectiveness of the integrated technique is tested against a simulated dataset.