Research On Imaging And Recognition Algorithm Of GEO Dual Base Moving Target Based On FRFT

The geostationary earth orbit bistatic synthetic aperture radar(GEO-BSAR)system is a passive bistatic synthetic aperture radar system with a special configuration.The transmitter of this system can be deployed on a stationary orbiting satellite,and the receiver can be placed on the surface of a satellite,an airplane or the earth.The imaging target can be a target on the ground or a target in the air,or a moving target or some stationary targets.The GEO-BSAR system has technical advantages of low deployment cost,wide exposure range,strong system concealment and geosynchronization,etc.It also has the advantages of good security,low development cost,high flexibility,good coverage,simple data processing,etc.These characteristics reduce the impact of the space-time characteristics of target detection,and has broad application prospects in military and civilian use.Using the advantages of GEO-BSAR system,this article first analyzes and explains the distance migration and imaging quality of stationary targets under the background of high orbit and long synthetic aperture time.Aiming at the large-distance migration of stationary targets in this scene,through the study of the GEO-BSAR system imaging algorithm of cascaded Keystone transformation,high-precision,fast-distance migration correction and accurate imaging of stationary targets are realized.Due to the greater distance migration caused by the moving target's own speed,and the influence of stationary targets and ground clutter on the moving target information,only the cascaded Keystone method is used in this scenario,and accurate imaging images of the moving target cannot be obtained.Therefore,this article combines the characteristics of Fractional Fourier Transform(FRFT)and Displaced Phase Center Antenna(DPCA),analyzes and explains the imaging and recognition process of moving targets in a single-static scene,an algorithm based on FRFT parameter estimation combined with Keystone transformation is proposed.This algorithm is used in the GEO-BSAR system to perform distance migration correction through Keystone transformation to obtain low-precision pre-imaging,then use DPCA technology to eliminate static clutter information.Finally,the FRFT-based parameter estimation is performed in the azimuth frequency domain,which effectively corrects the position offset and imaging defocus caused by the moving target,and obtains a clear image of the ground moving target.The simulation results show that the algorithm proposed in this article can achieve accurate distance migration correction,high-resolution imaging and recognition of moving targets.