合成孔径雷达的一种快视实时成像算法

A Real Time Quick Look Image Formation Method for Airborne SAR System

给出一种适于机载 SAR实时成像处理的快视方法 (RQL M)及其实现 ,该算法在方位向上采用非聚焦的处理方法。方位向非聚焦压缩的原始方法是采用一个固定宽度的时域矩形窗对方位向所形成的线性调频信号进行滑动滤波 ,使用简单的加法操作完成方位向非聚焦压缩。但由于矩形窗的旁瓣衰减慢 ,因而在图像中如果高频分布比较多 ,由于相位误差的加大会使图像质量变差。文中采用两个级联的可变宽度矩形窗来形成一个梯形窗 ,使窗函数的频率响应介于矩形窗和三角窗之间 ,可以通过调节两个矩形窗的宽度来调节频率响应的主瓣宽度和旁瓣衰减。从而调节方位向的分辨率、积分旁瓣比 (ISL R)和峰值旁瓣比 (PSL R) ,进而调节成像结果的质量。

In this paper,we present a real time quick look image formation method (RQLM) suitable for airborne stripmap SAR system.A unfocused azimuth copression method is used in this approach.With the basic unfocussed compression method,a fixed width rectangle window in time domain was used to process the azimuth chirp signal with a moving average and all of these were completed only using complex addition.Since the sidelobes of rectangle window are high,the image quality will be distorted by the augmented phase error when more high frequency components exist in images.In this paper, a trapezoidal window is formed of two cascaded rectangle windows with adjustable width and it's mainlobe width and peak sidelobe ratio (PSLR) can be adjusted though changing the durations of two rectangle windows to get suitable image.The same simple hardware architecture can be used to implement the new approach without any additional complexity,while the flexibility is retained.