SAR图像边缘混叠现象研究

摘要

针对SAR图像边缘混叠现象,本文从SAR数据接收机理及数据处理方式上分析了这种混叠现象的起因.分析发现,这种混叠现象与SAR接收数据信号特性及线性调频信号匹配压缩特性有关.与截短的线性调频信号的匹配压缩结果相似,SAR实际数据方位向、距离向起始位置和结束位置附近的目标回波数据被截断,因此对任意一部以线性调频信号为发射信号的SAR系统,其所得成像处理结果总会出现图像边缘混叠现象,且混叠区域大小正好为方位向和距离向上的半个脉冲持续时间的采样点.RADARSAT-1数据及线性调频信号的处理结果验证了上述结论的正确性.最后,本文给出选择无混叠SAR图像的两种方法.%The mechanism of SAR received data and the method of data processing are studied in this paper, to explore the causes of the phenomenon of SAR image edges aliasing. Analysis shows that the aliasing phenomenon is related to the signal characteristics of SAR received data and the matching compressing characteristics of linear FM signal. Similar to the matching compressing result of shorted linear FM signal, SAR image edges aliasing always arises in the result of SAR imaging for every SAR system which uses linear FM signal as its transmitting signal, and the aliasing region size of SAR image is just equal to the sampling numbers of half pulse duration both in azimuth direction and range direction, because echo samplings of SAR real data are truncated which nearby beginning and ending both of azimuth direction and range direction. The reliability of above conclusion was tested by processing result of RADARSAT-1 data and linear FM signal. Two methods are proposed to choose non-aliasing SAR image last in the paper.