An Azimuth Frequency Non-Linear Chirp Scaling (FNCS) Algorithm for TOPS SAR Imaging With High Squint Angle
An Azimuth Frequency Non-Linear Chirp Scaling (FNCS) Algorithm for TOPS SAR Imaging With High Squint Angle
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DOI：
10.1109/jstars.2013.2258893
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发表时间：
2014
影响因子：
5.5
通讯作者：
Yufeng Wu;Guangcai Sun;X. Xia;M. Xing;Jun Yang;Z. Bao
中科院分区：
文献类型：
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作者：
Yufeng Wu;Guangcai Sun;X. Xia;M. Xing;Jun Yang;Z. Bao
TOPS合成孔径雷达（SAR）斜视地形观测数据采集过程中，天线主波束的转向增加了方位带宽，导致方位信号在多普勒域出现混叠。此外，斜视TOPS SAR的距离曲率和线性距离走动校正后的多普勒频率调制（FM）率是方位变化的。这些问题给SAR数据处理带来了一定的困难。针对这一问题，本文提出了一种新的斜视TOPS SAR成像算法。线性距离走动校正后，进行方位预处理，得到无混叠的二维频谱。然后，利用一种改进的Chirp Scaling算法，对无子孔径的TOPS SAR数据进行了距离徙动校正（RCMC）和距离压缩。最后，提出了频率非线性线性调频定标（FNCS）来校正调频速率的变化，并通过频谱分析（SPECAN）方法将方位信号聚焦在多普勒域。仿真和真实的数据结果均表明了该算法的有效性。
During the data acquisition of a squint terrain observation by progressive scan (TOPS) synthetic aperture radar (SAR), the steering of the antenna main beam increases the azimuth bandwidth and results in the azimuth signal aliasing in the Doppler domain. Besides, the range curvature and the Doppler frequency modulation (FM) rates after linear range walk correction are azimuth-variant for squint TOPS SAR. These problems may cause some difficulties for the SAR data processing. To deal with the problems, a new imaging algorithm for the squint TOPS SAR is introduced in this paper. After linear range walk correction, the azimuth preprocessing is implemented to achieve the two-dimensional frequency spectrum without aliasing. Then, utilizing a modified chirp scaling algorithm, we complete the range cell migration correction (RCMC) and range compression to the TOPS SAR data without subaperture. Finally, the frequency nonlinear chirp scaling (FNCS) is proposed to correct the variation of the FM rates and the azimuth signal is focused in the Doppler domain via the spectral analysis (SPECAN) method. Both simulation and real data results show the effectiveness of the proposed algorithm.