空间目标双基地ISAR越多普勒单元徙动校正算法

针对双基地逆合成孔径雷达(ISAR)的越多普勒单元徙动问题,以转台模型为研究对象,分别从回波信号模型和散射点相对收发双站速度变化2个角度分析了越多普勒单元徙动的产生机理,并提出了基于距离单元相位补偿的多普勒徙动校正算法.该算法首先由双基地雷达与目标的几何关系估计出其等效旋转速度,然后通过等分观测期间的目标回波获取2幅不同观测视角的ISAR图像,依据图像旋转相关最大准则估计出图像的等效旋转中心,实现一维距离像的定标,最后对每个距离单元进行相位补偿,完成越多普勒单元徙动的校正.仿真实验表明,算法能有效解决双基地ISAR越多普勒徙动问题,提高ISAR成像质量.

Correction algorithm of migration through Dopplercells for space target in bistatic ISAR

Aiming at the problem of migration through Doppler cells in bistatic ISAR, based on bistatic ISAR turntable model, the reason of migration through Doppler cells from two aspects of echo model and the relative speed changes of scattered points was analyzed. The correction algorithm was presented based on range cell phase compensation. Firstly, target rotating rate was estimated through the geometrical relationship of bistatic stations and target. Secondly, the algorithm divided the echo data into two parts, and then imaging separately, getting two images of different angles of view. And the rotating center was estimated according to the maximum criterion of rotating correlation, which was used to range scaling. The migration through Doppler cells was corrected through phase compensation of each range cell at last. The simulation result show that the method could solve the problem of migration through Doppler cells, and could improve the image quality.