小转角下空间目标双基地ISAR二维成像算法

2D imaging algorithm for bistatic ISAR of space target in small rotating angle

为了解决小转角下空间目标双基地ISAR方位向分辨率下降的问题,提出基于AR模型数据外推的双基地ISAR成像算法。双基地ISAR成像时,小转角下的方位向回波可认为服从AR模型,据此建立线性预测方程,利用Burg熵最大法中的Levions递推估计预测系数,然后对方位向回波进行外推,最后基于原始数据和外推后的数据共同进行谱估计得到高分辨的二维图像。算法提高了小转角下方位向的图像分辨率,同时避免了长相干积累条件下双基地角变化等因素造成的图像散焦问题。仿真实验验证了算法的有效性。

In bistatic inverse synthetic aperture radar（ ISAR）, azimuth resolution decreases when imaging space target in small rotating angle. To solve this problem, algorithm based on auto regressive （ AR ） model dada extrapolation is presented. Echo in azimuth direction can be deemed to obey AR model in bistatie ISAR. Based on the property,linear prediction equation is established, and the Levions recursive method in maximum Burg entropy algorithm is used to estimate the prediction coefficients. The echo in azimuth direction is extrapolated in forward and backward, and the 2D image is estimated based on the original and extrapolated data together. The azimuth resolution is increased in small rotating angle, and the defocusing problem caused by bistatic angle variance is avoided in large accumulation time. Simulation experiment validates the availability of this algorithm.