An Improved SAC Algorithm Based on the Range-Keystone Transform for Doppler Rate Estimation
An Improved SAC Algorithm Based on the Range-Keystone Transform for Doppler Rate Estimation
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DOI：
10.1109/lgrs.2012.2220753
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发表时间：
2013-07
影响因子：
4.8
通讯作者：
Y. Wu;Guangcai Sun;X. Xia;M. Xing;Z. Bao
中科院分区：
文献类型：
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作者：
Y. Wu;Guangcai Sun;X. Xia;M. Xing;Z. Bao
多普勒频率是合成孔径雷达（SAR）信号处理中的一个重要参数，它影响SAR图像的聚焦效果。从SAR数据中估计多普勒频率的方法有很多，但有些方法不适用于聚束式SAR，因为聚束式SAR采用两步算法，方位向预处理后的信号在方位向时域会出现混叠。虽然移位相关（SAC）算法可能适用于这样的信号，但它是针对条带成像模式提出的;并且当它用于估计聚束SAR的多普勒速率时，可能会出现一些问题，例如来自零填充的高计算量和聚焦深度的约束。在这封信中，提出了一种改进的多普勒速率估计方法，称为Keystone-SAC算法。提出了一种迭代算法来估计模糊数，并分析了模糊数分裂为两个数的特殊情况。真实的聚束式SAR数据处理结果验证了该算法的有效性。
Doppler rate is an important parameter in synthetic aperture radar (SAR) signal processing since it affects the SAR image focusing. There are many approaches to estimate the Doppler rate from SAR data; however, some approaches are not appropriate for spotlight SAR, which is focused with the two-step algorithm, since, after azimuth preprocessing, the signal is aliased in the azimuth time domain. Although the shift-and-correlation (SAC) algorithm may be suitable for such signals, it is proposed for the stripmap imaging mode; and when it is used to estimate the Doppler rate for spotlight SAR, some problems, such as the high computational load from zero padding and the constraint of the focus depth, may occur. In this letter, an improved Doppler rate estimation approach, which is called the Keystone-SAC algorithm, is proposed. An iterative scheme is presented to estimate the ambiguity number, and a special case when the ambiguity number splits into two numbers is analyzed. The real spotlight SAR data processing results are used to validate the effectiveness of the proposed algorithm.