基于稀疏表示和时频变换的ISAR成像算法

摘要

逆合成孔径雷达对空中机动飞行目标进行成像,在成像积累时间内,成像投影平面和横向尺度随时间变化,许多参数很难准确提取,人们无法获得更多的先验知识.一般采用鲁棒性强的距离-多普勒(RD)算法进行成像,但传统的RD成像算法基于目标匀速转动和方位均匀采样的假设,若用其对机动目标进行成像,则图像模糊,尤其对于随机缺损的雷达回波数据,其成像质量显著下降,甚至无法辨识.通过引入稀疏表示和时频变换,提出了一种基于稀疏表示和时频变换的距离-瞬时多普勒成像算法,其可对一般机动飞行目标进行有效成像.实验结果验证了所提算法的有效性和可行性.%Inverse synthetic aperture radar images maneuvering targets, and during the coherent processing interval time, imaging projection plane and the scale of cross-range change with time, so many parameters are difficult to accurately extract and more prior knowledge can't be acquired. In general, the robust range-doppler (RD) imaging algorithm is used. But the conventional RD imaging algorithm is based on the hypothesis of the target rotating uniformly and sampling uniformity in azimuth. For maneuvering target imaging,RD algorithm will make the image fuzzy. Especially for radar gapped data, the performance of imaging descends greatly and even can't be identified. This paper introduced a range-instantaneous Doppler imaging algorithm based on sparse representation and time-frequency transform which can effectively image the maneuvering target. The experimental results validate the effectiveness and feasibility of this approach.