Research On Bistatic Forward-looking SAR Non-stationary Clutter Suppression

Since the transmitter and receiver of bistatic forward-looking synthetic aperture radar(SAR)are placed on different platforms,it has the advantages of antireconnaissance,good concealment,strong anti-interference and other advantages compared with monostatic SAR.Bistatic forward-looking SAR can also achieve high resolution imaging of the forward-looking scene of the receiver.Therefore,bistatic forward-looking SAR has important application value in the military and civilian firlds.Bistatic forward-looking SAR clutter suppression technology,which is to suppress the background clutter in the forward-looking region by using signal processing method,is the prerequisite for moving target detection.However,the clutter is strong nonstationary(the space-time distribution of different range cells are inconsistent),which seriously affects performance of clutter suppression and moving target detection.In this thesis,the non-stationary compensation of clutter and clutter suppression are studied,and the main work is following:1.Space-time-range 3-D model of bistatic forward-looking SAR echo is established.Range cell migration,Doppler frequency,space frequency of moving targets and clutter scatterers are analyzed.Meanwhile,the non-stationary characteristics and space-time spectrum extension of clutter in different bistatic configuration is studied,which lays a theoretical basis for the subsequence research.2.The clutter non-stationary compensation method based on clutter spectrum center compensation and time-varing weighted method is studied.The influence of clutter nonstationary on the existing method are analyzed.3.A bistatic forward-looking SAR clutter non-stationary compensation method based on prior information of attitude is proposed,which solves the problem of accurate estimation of clutter covariance matrix.Meanwhile,the performance of the proposed method is compared with that of the existing non-stationary compensation methods,which lays an important premise for effective clutter suppression based on space-time adaptive processing(STAP).4.A clutter suppression method based on multi-pulse two-channel cancellation is proposed,which solves the problem of clutter suppression caused by space-time spectrum extension of bistatic forward-looking SAR.This method achevies effective clutter suppression of bistatic forward-looking SAR,and laying a foundation for highly reliable detection of moving targets.The effectiveness of the above methods is verified by theoretical analysis and simulation experiments,and the bistatic forward-looking SAR clutter suppression can be realized.