双基地角时变下的ISAR等效旋转中心估计

双基地逆合成孔径雷达（ISAR）距离-多普勒算法成像时，容易引起越分辨单元徙动问题，影响成像质量，为了抑制越分辨单元徙动，需要估计目标的等效旋转中心。本文针对双基地角时变下的ISAR等效旋转中心估计问题，提出了一种等效旋转中心估计算法。该算法首先将运动补偿后的一维距离像序列分为两组并分别成像，得到两幅图像；其次，假定某个距离单元为等效旋转中心位置，对两幅图像进行畸变校正，使得两幅图像只存在一个视角差，按视角差旋转其中的一幅图像，并与另一幅图像作相关，得到相关系数；然后，假定下一个距离单元为等效旋转中心位置，重复上述步骤，直至遍历结束，相关系数最大值对应的假定位置就是估计的等效旋转中心。最后进行了仿真对比实验，表明本文算法能够有效估计双基地角时变下的ISAR等效旋转中心位置。

Rotation center estimation of bistatic ISAR in presence of time-varying bistatic angle

When range-Doppler algorithm is used in bistatic Inverse Synthetic Aperture Rador (ISAR), migration through resolution cell may occur in bistatic ISAR, affecting the imaging quality. To suppress migration through resolution cell, it is necessary to estimate the equivalent rotation center of the target. Aiming at the problem in the rotation center estimation of the bistatic inverse synthetic aperture radar in the presence of time-varying bistatic angles, a rotation center estimation algorithm is proposed in this paper. Firstly, one-dimensional range image sequences after motion compensation are divided into two groups, obtaining two images separately. Secondly, assuming that a range cell is the equivalent rotation center, we correct the distortion of the two images so that only one angle difference of view exists between the two images. Based on the difference of viewing angle, we rotate one of the images and correlate it with the other image, obtaining the correlation coefficient. Then, assuming the next range cell is the position of the rotation center, we repeat the above steps until the end of the traversal, and the assumed position corresponding to the maximum correlation coefficient is the estimated equivalent rotation center. Finally, the simulations are carried out and the results show that the method in this paper can effectively estimate the rotation center of the bistatic ISAR in the presence of time-varying bistatic angles.