基于FRFT的大型平稳目标ISAR成像算法  

A New ISAR Imaging Algorithm for Steadily Flying Big Targets based on FRFT

作　　者：曹敏[1] 付耀文[1] 黎湘[1] 庄钊文[1] 

机构地区：[1]国防科技大学电子科学与工程学院,长沙410073

出　　处：《信号处理》2009年第9期1458-1462,共5页Journal of Signal Processing

基　　金：国家部委基金资助课题

摘　　要：逆合成孔径雷达(ISAR)通常忽略越距离单元走动(MTRC),采用距离多普勒(RD)算法进行ISAR成像。但对于高分辨ISAR成像雷达,当目标尺寸较大时,距目标中心较远的散射点会产生MTRC,从而导致ISAR像质量下降。为避免散射点的MTRC,本文提出了一种基于分数阶傅立叶变换(FRFT)的ISAR成像算法。从多普勒域看,MTRC是由信号频率和多普勒频率耦合引起的。本文算法以此为基础,利用FRFT的Chirp-multiplication性质对多普勒域进行尺度变换,实现信号频率与多普勒频率的解耦合,获得目标横向像,然后利用IFFT进行径向压缩,无需越距离单元走动校正即可获得清晰的ISAR像。该算法不需要已知目标的转动信息,实现简单,而且计算量与RD算法相当。仿真数据和暗室测量数据验证了算法的有效性。The Range-Doppler （RD） algorithm is widely used in inverse synthetic aperture radar imaging （ISAR）. In the RD algorithm,the migration through resolution cells （MTRC） due to target rotation is usually ignored. However, with the improvement of the target size or the increase of the coherent angle, MTRC cannot be ignored for the high resolution radar. If still using RD algorithm to imaging, the ISAR image will be distorted. In order to improve the quality of ISAR images, a new ISAR imaging algorithm based on fractional Fourier transform is proposed. In the Doppler domain, MTRC can be considered as the coupling between the signal frequency and the Doppler frequency. Based on this fact, the Chirp-multiplication property of FRFT is applied to realize the Doppler scale transform. Through the processing, the coupling between the Doppler frequency and the signal frequency can be removed and cross-range profiles are obtained. Then FFT is used for each cross-range cell and the ISAR image is obtained without the mitigation of MTRC. The proposed algorithm not only can be implemented easily without the information of the target rotation, but also has the comparative computation load with RD algorithm. The simulation data and real data results demonstrate the effectiveness of the proposed algorithm.

关 键 词：逆合成孔径雷达成像 分数阶傅立叶变换 越距离单元走动 

分 类 号：TN957[电子电信—信号与信息处理]