Study On STAP Algorithm For Airborne Radar In Nonhomogenous Environments

Space-Time Adaptive Processing (STAP) techonology that effectively suppresses clutter bytwodimentional filter greatly improves the detection performance of airborne phased array radar. Forconventional STAP approaches, a key step is to adaptively estimate the clutter plus noise covariancematrix, in which the training sample must be independent identically distributed (I.I.D) with the cellunder test. Unfortunately, in practical processing, the clutter environments always present to beheterogeneous. That means the I.I.D assumption will never valid, which finally leads to performanceloss of STAP. This dissertation focuses on the investigation of clutter suppression techniques forairborne radar in nonhomogeneous environment. The major work is summarized as follows:1The clutter model for airborne radar is investigated and the clutter characteristic is analyzed.Basic theories such as optimal STAP weight vector as well as several criterions to evaluate theperformance are introduced. Experimental results with respect to measured data collected by athree-channel airborne radar are employed to verify the related theories and algorithms.2The influence to STAP caused by interference target and isolated interference is analyzed. Thennonhomogeneity detectors based on generalized inner product (GIP) and adaptive power residual(APR) are studied. For isolated interference, direct data domain (DDD) algorithm is investigated andverified by simulation as well as experimental results.3The decompose principle of multistage wiener filter (MWF) is analyzed. The MWF does notutilize the clutter covariance matrix estimation, inversion and eigendecomposition techniques, whichdramatically improves the computational efficiency as well as the convergence rate. Then, threeimplementations of the MWF are investigated and verified by both simulation and experimentalresults.4The Space-Time Autoregressive (STAR) algorithm is investigated and verified by simulationas well as experimental results. To remedy the serious space-time aperture loss caused by sub-aperturesliding operation in DDD algorithm, an algorithm that employes STAR algorithm to solve the weightvector of DDD is proposed for the detection of moving targets disturbed by isolated interference.Simulation and experimental results show that the proposed algorithm obtains better performance thanthe conventional DDD algorithm with low aperture loss.