A Modified Fixed-Point Chirp Scaling Algorithm Based on Updating Phase Factors Regionally for Spaceborne SAR Real-Time Imaging
A Modified Fixed-Point Chirp Scaling Algorithm Based on Updating Phase Factors Regionally for Spaceborne SAR Real-Time Imaging
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DOI：
10.1109/tgrs.2018.2852062
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发表时间：
2018-08
影响因子：
8.2
通讯作者：
Zegang Ding;F. Xiao;Yizhuang Xie;Wenyue Yu;Zhu Yang;Liang Chen;T. Long
中科院分区：
文献类型：
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作者：
Zegang Ding;F. Xiao;Yizhuang Xie;Wenyue Yu;Zhu Yang;Liang Chen;T. Long
为了实现星载合成孔径雷达（SAR）的Chirp Scaling（CS）算法实时成像，相位因子的产生速率高，计算量大。例如，在2-D时间或频率空间中连续地更新相位因子对于生成用于实时成像的相位因子是困难的。针对这一问题，提出了一种基于相位因子区域更新的CS算法。此外，传统的浮点算法是无法负担的实时成像机载。因此，采用定点处理。在该算法中，相位因子只在特定的时间和频率上更新，并采用定点运算。基于成对回波理论和有限字长误差数学模型，研究了该算法对SAR成像质量的影响。在此基础上，结合中国HJ-1C和GF-3星载SAR实测数据，构建了以数字信号处理器和现场可编程门阵列板为核心的硬件系统。
To realize real-time imaging for the spaceborne synthetic aperture radar (SAR) using the chirp scaling (CS) algorithm, high generation rates of phase factors and heavy computation loads are unavoidable. For example, updating phase factors continuously in the 2-D time or frequency space is difficult for generating phase factors for real-time imaging. To solve this problem, a modified CS algorithm based on updating phase factors regionally is proposed. Moreover, conventional floating-point arithmetic is unaffordable for real-time imaging onboard. Therefore, fixed-point processing is adopted. In the proposed imaging algorithm, the phase factors are updated only at some specified times and frequencies, and fixed-point operation is adopted. Furthermore, based on the paired echo theory and the finite word length error mathematical model, the effect of the proposed imaging algorithm on the SAR image quality is studied. Moreover, based on the above analysis and the experiments of Chinese HJ-1C and GF-3 spaceborne SAR practical measured data, a hardware system including digital signal processor and field-programmable gate array boards is constructed.