The spaceborne stripmap range sweep synthetic aperture radar (SAR) (SS-RSSAR) is a new-concept SAR mode proposed to efficiently image regions of interest (ROI) squinted with respect to satellite orbit. The most distinct feature of the SS-RSSAR is the beam sweeping in the elevation for continuous squinted ROI illumination. A wide nonlinear chirp scaling algorithm (WNLCSA) has been proposed to directly implement image formation along the ROI spreading direction. However, the algorithm efficiency is limited due to its time-consuming time-domain interpolation. In this letter, a new interpolation free WNLCSA (IF-WNLCSA) is proposed for more efficient SS-RSSAR imaging by substituting the interpolation with a much faster chirp scaling approach. Different from the interpolation, the chirp scaling induces additional range migration and Doppler modulation, both of which, however, are neglected due to their weak influences on imaging. The derivation of the chirp scaling is presented in detail, followed by the analyses on the algorithm accuracy and efficiency. The presented approach is evaluated by both the point- and extended-target simulations.

中文翻译：

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星载带状图距离扫描SAR成像的无插值宽非线性线性调频缩放算法

星载条带式距离扫描合成孔径雷达 (SAR) (SS-RSSAR) 是一种新概念 SAR 模式，旨在有效地对相对于卫星轨道斜视的感兴趣区域 (ROI) 成像。SS-RSSAR 最显着的特点是光束在仰角扫过，用于连续斜视 ROI 照明。已经提出了一种宽非线性线性调频缩放算法（WNLCSA）来直接实现沿 ROI 传播方向的图像形成。然而，算法效率由于其耗时的时域插值而受到限制。在这封信中，通过用更快的线性调频缩放方法代替插值，提出了一种新的无插值 WNLCSA（IF-WNLCSA），用于更有效的 SS-RSSAR 成像。与插值不同，线性调频缩放会引起额外的距离偏移和多普勒调制，然而，由于它们对成像的影响较弱，这两者都被忽略了。详细介绍了chirp缩放的推导，然后分析了算法的准确性和效率。所提出的方法通过点和扩展目标模拟进行评估。