一种超高分辨率机载聚束SAR两维自聚焦算法

 受运动参数测量误差和大气扰动等因素影响,合成孔径雷达(SAR)图像通常会发生散焦,利用自聚焦对散焦的SAR图像进行后处理是一种有效的重聚焦手段。传统的自聚焦算法都只是针对方位一维相位误差的估计和补偿。随着成像分辨率的提高,自聚焦时残留距离徙动的校正成为SAR成像面临的一个新挑战。本文推导得到了极坐标格式算法处理后残留距离徙动和方位相位误差的解析表达式,分析了两者之间的内在关系,并利用该关系,提出了一种能够同时进行残留距离徙动和方位相位误差补偿的两维自聚焦算法。实测数据处理结果表明,在残留距离徙动效应不可忽略的条件下,该方法能够极大地改善原有自聚焦算法的聚焦性能。

2-D Autofocus Algorithm for Ultra-high Resolution Airborne Spotlight SAR Imaging

Synthetic aperture radar(SAR) images are often blurred by phase perturbations induced by uncompensated sensor motion and / or unknown propagation effects caused by turbulent media.To get refocused images,autofocus proves to be useful post-processing technique applied to estimate and compensate the unknown phase errors.However,an important drawback of the conventional autofocus algorithms is that they are able to compensate for only one-dimensional azimuth phase errors.As the resolution increase,residual range cell migration,which makes the defocus inherently two-dimensional(2-D),becomes a new challenge.In this paper,the analytical relationship between the residual range cell migration and azimuth phase error in polar format imagery is developed.Utilizing this relationship,a 2-D autofocus algorithm that can simultaneously compensate for the residual range migration and azimuth phase error is proposed.The results of real data processing validate the effectiveness of the proposed method.