一种用于距离维复杂空变多普勒SAR成像的改进运动补偿方法

沿距离维复杂空变的多普勒对SAR成像质量有很大影响，常规的距离多普勒 (RD)算法处理结果容易出现明暗交替现象，图像可视性较差。通过在方位预滤波和方位脉冲压缩时，沿距离块/门估计或者计算多普勒频率，在方位预滤波和方位脉压时把窗函数根据多普勒频率沿方位移动，能有效解决明暗交替现象，但是这种处理方法无法改善距离近端或远端的聚焦效果。基于上述问题，该文提出一种改进的运动补偿方法，通过沿距离维分块进行运动补偿和走动校正，把沿距离空变的多普勒校直，然后进行方位脉压处理。所提方法处理结果没有明暗交替现象，图像沿距离维连续完整，可视性较好，同时在远离距离中心处还具有良好的聚焦效果。实测数据处理结果验证了该算法的有效性。

An Improved Motion Compensation Algorithm for Range Complex Spatial Variant Doppler SAR Imaging

The complex spatial variant Doppler along the range dimension has large influence on SAR imaging quality, the normal range Doppler (RD) algorithm is easy to produce the phenomenon of alternating light and dark, image visibility is poor. During azimuth pre-filtering and azimuth pulse compression estimation or calculation the Doppler frequency along range block/gate, in azimuth pre-filtering and azimuth pulse compression, the window function is moved along the azimuth according to Doppler frequency can effectively solve the phenomenon of chiaroscuro, however, this method can not improve the focusing effect in near or far range. Based on the above problems, an improved motion compensation method is proposed in this paper, motion compensation and motion correction are performed by dividing the blocks along the range dimension, collimation of a spatially variable Doppler along range and then azimuth pulse compression is carried out. There is no alternation of light and dark in the proposed method processing results, the image is continuous and complete along the range dimension and has better visibility. At the same time, the image has a good focusing effect at far distance from the range center. The validity of the algorithm is verified by the measured data.