High Precision Imaging Algorithm For Arc-GBSAR Based On Back Projection Algorithm

Arc scanning Ground based SAR(Arc scanning GBSAR)system is type of novel GBSAR system.The system utlizes the antennas mounted on the end of the boom(The boom is extending from the center of the rotating platform.)to scan the scene around the system in 360 degrees,which means that it has the large field of view.In view of the unique advantages of the Arc scanning GBSAR system,the system has become a current research hotspot and has received extensive attention from domestic and foreign experts.However,although some teams at home and abroad have been committed to verifying the feasibility of the Arc scanning GBSAR system and researched its imaging algorithm in recent years,the imaging of this system still has difficulties to be solved urgently.The imaging accuracy of the Arc scanning GBSAR system is affected by terrain fluctuations.Even if several targets in the imaging scene have the same distance from the antenna and have the same Doppler,if the heights of these targets are different,their range migration will be different.The traditional the Arc scanning GBSAR imaging algorithm achieves imaging on a fixed-height imaging reference plane.Therefore,the height difference between the imaging reference plane and the imaging target will cause the range migration cannot be correctly compensated,which will cause the quality of the Arc scanning GBSAR imaging results to decrease and even the SAR image to be defoucsed.In this paper,a systematic and in-depth study is carried out on the high-resolution imaging of the the Arc scanning GBSAR system.The main work of this paper are as follows:(1)The basic geometric model and signal model of the Arc scanning GBSAR system are established.Based on the basic geometric model and signal model,we derive the error model of the traditional Arc scanning GBSAR system imaging algorithm.Besides,The effects of experimental parameters such as target height,boom rotation radius,antenna beam width,rotation angle,signal wavelength,and signal bandwidth on the accuracy of Arc scanning GBSAR system imaging are also explored.(2)Based on the research and analysis of the traditional Arc scanning GBSAR imaging algorithm error model,a high precision imaging method for Arc scanning GBSAR based on back projection algorithm is proposed.We utlize the back projection algorithm to acquire the SAR image of the scene,and using DEM to assist imaging.With the assistance of DEM data,the target can be imaged at its real height,which means that range migration can be correctly compensated.(3)The SAR image pair used to extract the DEM of scene is obtained by the traditional Arc scanning GBSAR imaging algorithm,which means that if the height of the imaging target is not the same as the height of the imaging reference plane,the imaging result will have reduced accuracy or even defocusing.Therefore,we analyze the influence of defocused SAR imaging results on the accuracy of the DEM obtained by interference,and prove that even if the traditional imaging method will cause the SAR imaging results to decrease in accuracy or even defocus,the impact on the accuracy of the DEM can be ignored.Besides,the application background of the Arc scanning GBSAR system in this paper is ground deformation monitoring.Thus we analyze the impact of the high-precision imaging method of the Arc scanning GBSAR proposed in this paper on the accuracy of ground deformation monitoring.(4)In order to improving the efficiency of extracting the DEM of scene,we hope to efficiently obtain SAR image pairs for obtaining DEM.So in this paper,a large field of view fast imaging algorithm for Arc scanning GBSAR systems is proposed.The echo signal of the proposed fast imaging algorithm is focused in the frequency domain,which means it can efficiently acquire SAR image pairs,thereby improving the efficiency of DEM acquisition.