Research On SAR Imaging Algorithm Of Complex Trajectory And Implementation Of Signal Processor

Complex trajectory synthetic aperture radar(CTSAR)can adapt to the movement of radar platform in all directions,and has great application prospects in navigation,search and other fields.Because of the uncertainty of the complex trajectory,SAR imaging processing needs to compensate the movement of the radar platform in all directions.The imaging algorithm is complex and difficult to process in real time.In this paper,according to the application requirements of real-time signal processing of complex trajectory SAR,the existing imaging algorithm of complex trajectory SAR is analyzed,and the adaptive pulse spacing method is proposed to eliminate the non-uniform sampling caused by the speed change of radar platform along the track direction,and the imaging steps are given in combination with PFA algorithm.A signal processor system is designed around the imaging algorithm to realize the real-time processing of the algorithm and the actual scene imaging experiment.The main research contents are as follows:1?Based on the complex trajectory SAR imaging,the geometry structure is established,the echo model is derived and the echo characteristics are analyzed.An adaptive method of pulse spacing is proposed,and the echo model after adaptive pulse spacing is derived,and the Doppler characteristics of echo are analyzed.Combining the pulse spacing adaptive method with PFA algorithm,the imaging steps are given and verified by simulation.2?According to the characteristics of large amount of imaging data and complex operation of complex trajectory SAR,a signal processing system based on VPX architecture is designed with FPGA + DSP as the core.The calculation amount of the algorithm is calculated,the specific models of FPGA and DSP are selected according to the calculation amount of the algorithm,and DDR3 is designed according to the memory requirements of the algorithm.And design data acquisition board,signal processing board,interface board and backplane.3?The steps of imaging algorithm are divided,down conversion,pulse compression,phase compensation and other preprocessing steps are completed on the FPGA of the acquisition card,and the more complex operation of polar format conversion is completed on the DSP of the signal processing card.According to the calculation amount of the algorithm,four DSPs are allocated the calculation tasks equally,the time-consuming of the imaging algorithm is optimized,and each functional module in the signal processor system is configured,and the data link interface is debugged.After the debugging of the whole signal processor,the imaging experiment is carried out in the field to verify the function and real-time of the imaging system.