一种低信噪比下的ISAR成像实现方法  

An implementation method of ISAR imaging at the low SNR level

作　　者：陈文驰[1] 刘飞[1] 

机构地区：[1]江南大学通信与控制工程学院,江苏无锡214122

出　　处：《电波科学学报》2010年第3期585-589,共5页Chinese Journal of Radio Science

基　　金：新世纪优秀人才支持计划(NCET-05-0485);江南大学青年科技基金

摘　　要：在逆合成孔径雷达成像中,对低信噪比的回波数据,常规的运动补偿方法不再适用,提出一种适用于低信噪比回波数据的成像实现方法。利用Radon变换提取目标径向速度粗估计,补偿回波消除多普勒模糊,以Keystone变换校正由目标速度引起的线性距离走动,在全局意义下以最小熵准则完成二次项距离走动的校正。在横向作多普勒分辨时,考虑各目标散射点子回波可近似为线性调频信号,引入修正离散Chirp-Fourier变换,并结合逐次消去技术,避免复杂的相位补偿,直接得到目标的距离-多普勒像。给出了应用该方法的具体步骤,仿真实验结果证明了该方法的有效性。For echo data with low input signal noise ratio （SNR） in the process of in verse synthetic aperture radar （ISAR） imaging, the conventional motion compensation method is invalid. In this paper, a new implementation method of ISAR imaging is proposed to deal with the data with low input SNR. A rough estimation of the radial velocity is extracted using the Radon transform. A Keystone transform is then employed to eliminate the effects of linear range migration caused by the radial velocity of the target. An entropy-minimization principle based compensation algorithm is used to correct the second-order range migration. When the radar target moves smoothly, the Doppler variation of subechoes from scatterers can be approximated as a first-order polynomial. Therefore, for avoiding complex phase adjustment, the modified Chirp-Fourier transform combined with the CLEAN technique is applied to each range cell to obtain the cross-range profiles of the target. Steps of this method for ISAR data with low input SNR are detailed. Simulations show the effectiveness of the new method.

关 键 词：逆合成孔径雷达 低信噪比 KEYSTONE变换 修正离散Chirp—Fourier变换 

分 类 号：TN957.51[电子电信—信号与信息处理]