Research On Ground Slow Moving Targets Detection And Imaging Methods By Monostatic/Bistatic SAR

In recent years, the moving targets detection and imaging technology is a hot direction in SAR research. In this paper, the method of slow moving targets detection and imaging by the airborne SAR and GEO spaceborne-airborne bistatic SAR is studied. Firstly, the effects of target movement to SAR imaging and clutter feature are analyzed, and the imaging method of GEO SAR is also studied. Then the characteristics and parameters of spaceborne-airborne bistatic SAR system are analyzed, and the imaging model is constructed. On this basis, using the Doppler Distribution Weighed method to estimate the echo signal’s two-dimensional spectrum, and combining with the Inverse Scaled Fast Fourier Transformation method to realize the imaging of GEO spaceborne-airborne bistatic SAR. Further the method of slow moving targets detection and imaging by the airborne SAR is studied, and a detection algorithm that using two-channel DPCA- CFAR combined with Frft for clutter suppression and target speed estimating is put forward. Further, the method of three-channel DPCA-ATI combined with Frft is used to realize slow moving targets detection and imaging by GEO spaceborne-airborne bistatic SAR. The main contents are as follows:1) Based on SAR echo equation of moving targets, the moving target Doppler center frequency and Doppler rate are derived, and the effects of target velocity and acceleration for imaging are analyzed. Then the characteristics of gro und clutter are analyzed, and it is stated that the key of slow moving targets detection is clutter suppression. Finally the imaging method of GEO SAR is studied, and a kind of improved CS algorithm in squint model based on curve trajectory and considers of the cubic phase compensation is put forward.2) According to the structure characteristics of GEO spaceborne-airborne bistatic SAR system, the indexes of synthetic aperture time, imaging bandwidth, fuzzy performance, resolution performance, Doppler performance and feasibility are put forward, and a set of reasonable simulation parameters are given.Considering the sending and receiving platform’s isomerism, it i s concluded that the key of imaging is to derive the echo signal’s two-dimensional spectrum,then using the Doppler Distribution Weighed method to estimate the two-dimensional spectrum, and combining with the Inverse Scaled Fast Fourier Transformation method to image.3) For airborne SAR system, slow moving targets detection and imaging method is studied, and a detection algorithm of DPCA- CFAR combined with Frft is put forward the, then the maximum detectable velocity and minimum detectable velocity are derived to indicate the detection performance of the algorithm.4) According to the structure characteristics of GEO spaceborne-airborne SAR system, the three-channel moving target detection model is constructed. The method of three-channel DPCA-ATI combined with Frft for slow moving targets detection and imaging is proposed. And the algorithm process is derived,then the algorithm’s detection performance in different SCR is ana lyzed by simulation to indicate the algorithm’s advantage.