低信杂(噪)比情况下机载雷达的舰船目标成像  

Airborne Radar Imaging of Ship Targets at the Low SNR Level

作　　者：李燕平[1] 李亚超[1] 邢孟道[1] 保铮[1] 

机构地区：[1]西安电子科技大学雷达信号处理重点实验室,陕西西安710071

出　　处：《电子学报》2008年第3期433-439,共7页Acta Electronica Sinica

基　　金：国家自然科学基金(No.60502044)

摘　　要：传统的针对飞机目标的成像方法一般要求高信杂(噪)比以保证回波的强相关性,然而受海杂波和噪声的影响,舰船目标回波的信杂(噪)比可能不高.本文提出一种低信杂(噪)比情况下机载雷达对舰船目标的成像方法.该方法首先对回波数据进行慢时间尺度变换,去除距离频率-方位时间的二次耦合,再采用最小熵准则对包络斜率进行搜索,校正剩余的距离走动,最后利用分数阶傅立叶变换对多个散射点的参数进行估计,得到舰船目标的瞬态像.理论分析及实测数据的成像结果表明,针对低信杂(噪)比数据的处理,该方法优于传统方法.The conventional methods for aircraft targets imaging often require that the correlation of the radar returns is high enough, thus, the SNR level of the radar returns should be high enough. However, due to the existence of the sea clutter and the noise, the SNR level of the radar returns may be low. In this paper, a novel method is proposed for airborne radar imaging of ship targets at the low SNR level. To eliminate the second order coupling between the range frequency and the slow time,the slow time scaling transformation is first applied on the raw data. Then,based on the minimum entropy criterion, the slope of the envelope is searched, leading to an accurate correction of the residual range walk. And then, the fractional Fourier transformation is used to esti- mate the parameters of the scatters.After that,the instantaneous image of the ship targets is obtained. The analysis and the imaging results of real data show that, for the processing of the data with a low SNR, the performance of the proposed method is better than that of the conventional one.

关 键 词：合成孔径雷达 低信杂(噪)比 雷达成像 参数估计 分数阶傅立叶变换 

分 类 号：TP957[自动化与计算机技术]