Research On SAR Time And Frequency Synchronization Technology For Bistatic Movement Platform

Bistatic synthetic aperture radar(Synthetic Aperture Radar,SAR)is a typical bistatic movement platform radar system.It can receive from close distance and transmit from remote distance due to its transmitter and receiver mounted on different platforms,and it has the ability of forward and view imaging.Compared to monostatic SAR,bistatic SAR has the characteristics of anti-reconnaissance,strong concealment,and strong antijamming.So it plays an extremely important role in military and civilian detection fields.However,separate transceivers also bring other problems to the system,and timefrequency synchronization error is one of the difficulties that must be solved.In the configuration of the bistatic movement platform,the high-speed moving transceiver platforms will cause positioning errors,motion errors and other factors that may affect the time-frequency synchronization effect.In this thesis,based on the timefrequency synchronization method of direct waves,the following work is carried out for the time-frequency synchronization technology in the case of the split motion platform configuration:1.The echo model and time-frequency synchronization error model of the bistatic movement platform SAR is established,the characteristics of the target's range migration,Doppler frequency are analyzed,and the influence of the time-frequency synchronization error on the imaging is studied,which lays a theoretical basis for the method of frequency synchronization error estimation and compensation.2.The SAR time-frequency synchronization method of the bistatic movement platform based on the direct signal is studied,the estimation effect of the direct signal synchronization method on the time and frequency synchronization error is analyzed,and the positioning error and motion error caused by the configuration of the bistatic movement platform are quantitatively analyzed for the method of direct signal synchronization.3.Aiming at the problem that the lack of positioning accuracy under the configuration of the bistatic movement platform will cause errors in the error value estimated by the direct signal synchronization method,a direct signal synchronization method based on the expansion of the number of pulse processing is proposed,which suppress the estimation error of synchronization error caused by positioning error.4.Based on the direct signal time-frequency synchronization method that expands the number of inter-pulse processing,a method of calculating and compensating image information entropy is proposed to calculate the optimal inter-pulse interval number,and the optimal estimation effect of time-frequency synchronization error is realized under the configuration of bistatic movement platform.The effectiveness of the above works are verified by theoretical analysis and simulation experiments,the problem of insufficient positioning accuracy of the direct signal time-frequency synchronization method under the configuration of the bistatic movement platform is solved,and the search of the optimal solution of the time-frequency synchronization error is realized.