Research On Imaging And Trajectory Tracking Technology Of Ground Moving Target Based On Airborne Single Channel CSAR

Circular Synthetic Aperture Radar(CSAR)has all-weather,all-weather detection capability,which can obtain three-dimensional microwave images of observation objects.In recent years,Ground Moving Target Indication(GMTI)technology has attracted widespread attention of domestic and foreign research institutions.Because the movement of the target introduces additional range walking and bending,the moving target on the CSAR image will appear defocused and position shifted,which seriously affecting its image quality.Therefore,based on the single-channel moving target detection,this paper implements moving target parameter estimation,refocusing and driving trajectory reconstruction.The research improved the moving target imaging performance of CSAR system.The main research results obtained are as follows:1.Research on the CSAR sub-aperture fitting method.Firstly,a spatial model of the moving target is established.Next,the sub-aperture of the CSAR full aperture is divided,and the sub-aperture fitting method is proposed.This method combines the motion characteristics of the CSAR platform and uses a parabola with a special curvature to fit the sub-aperture,simplifying the coupling between the parameters.Finally,using the method of numerical simulation,it is verified that under the same aperture length,the fitting error of the proposed method is significantly smaller than that of the traditional fitting method.2.Research on the refocusing and trajectory reconstruction of uniformly moving targets based on the second-order Keystone transform.Firstly,the motion parameter estimation and the refocusing results of the uniformly moving target are obtained.On this basis,a joint parameter estimation method for sub-aperture is proposed.This method not only improves the estimation accuracy of the motion parameters in the sub-aperture,but also obtains the estimation results of the position parameters.Finally,realized the trajectory reconstruction of the moving target.Compared with traditional time-domain algorithms,the execution efficiency of the proposed method is improved by an order of magnitude,laying a foundation for real-time imaging tracking of moving targets.3.Research on the refocusing and trajectory reconstruction of uniformly accelerating moving targets based on the second-order Keystone transform.In the accelerate model,the coupling between the motion parameters and position parameters of the moving targets are more serious.The accurate estimation results of each parameter cannot be obtained,and the difficulty of refocusing and trajectory reconstruction increases.Therefore,this paper proposes a new parameter estimation method.The method improves the processing efficiency and obtains the motion parameters estimation and refocusing results in the sub-aperture time.At the same time,using the sub-aperture joint parameter estimation algorithm,the position parameters estimation and the trajectory reconstruction results of the moving target are obtained.4.Researched the refocusing and trajectory reconstruction of curved moving targets based on road information assistance.Aiming at the target of uniform speed curve motion and uniform acceleration curve motion,an arc fitting model and a parabola fitting model are established respectively.Then,the curve fitting algorithm and nonlinear optimization algorithm are proposed.The proposed algorithms can obtain the motion parameters estimation results,and achieve the refocusing of the curved moving target.Finally,using the a priori information of the road,we obtain the position parameters estimation results of the moving target.The driving trajectory of the curved moving target is reconstructed.