Stap performance in site-specific clutter environments

Space-time adaptive processing (STAP) assumes the availability of an ample supply of independent and identically distributed secondary data from a homogeneous clutter environment to estimate the covariance matrix, but typical airborne sensor systems operate under heterogeneous, site-specific clutter circumstances. Sitespecific clutter exhibits several types of heterogeneity, including varying amplitude and spectral characteristics as a function of azimuth and range, which lead to degradation of the STAP filter. Utilizing site-specific clutter prediction based on cultural databases, the effects of different types of clutter heterogeneity can be isolated to help determine the most important parameters for STAP design. Characterization of the effect of heterogeneous clutter on the STAP, and fusion of a priori operating environment knowledge into a knowledge-aided and expert reasoning filter design philosophy, offer potentially significant improvements in target detection and data screening capabilities. Several scenarios are presented to demonstrate the effects of site-specific clutter heterogeneity on the performance of STAP algorithms. Examples of intelligent screening of secondary data, showing 10 to 20 dB improvement in signal-to-interference plus noise ratio (SINR) loss in measured data, and synthetic aperture radar based pre-filtering of discretes are also discussed. This research was supported under US Air Force Contract Number F30602-02-C-00 1 1. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressed or implied, of the Defense Advanced Research Projects Agency or the U.S. Government. This paper presented at the 2003 IEEE Aerospace Conference, Big Sky, MT, USA. March 8-15.2003. 0-7803-7651-X/03/$17.00