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利用MIMO-SAR系统相比传统SAR系统易获得更大空间自由度的特点,可进一步提高杂波抑制的性能。但对机动目标进行处理时,目标检测会受到目标非线性距离单元徙动影响,并且传统的运动参数估计方法难以准确获取合成孔径时间内的时变参数信息,这些极易造成目标在图像中出现散焦与模糊的现象。为此,文中采用长相干积累孔径划分的方法,消除越距离单元徙动对STAP性能的影响,并且将时变多普勒参数的非线性估计问题转化为对多个线性参数估计。仿真结果验证了文中方法的有效性。
Compared with the traditional SAR system, MIMO-SAR system can obtain more space degree of freedom, which can further improve the performance of clutter suppression. However, when the maneuvering target is processed, the target detection will be affected by the migration of the target non-linear distance element, and the traditional motion parameter estimation method can not accurately obtain the time-varying parameter information within the synthetic aperture time, which can easily cause the target to appear in the image Defocused and fuzzy phenomenon. Therefore, in this paper, the method of long coherent accumulation of aperture is adopted to eliminate the influence of distance cell migration on the performance of STAP, and the nonlinear estimation problem of time-varying Doppler parameters is transformed into multiple linear parameters estimation. Simulation results verify the effectiveness of the proposed method.