速度聚束调制对顺轨干涉SAR浅海地形成像的影响研究

摘要

Such an along-track interferometric SAR (ATI-SAR) as the conventional SAR can also be affected by the velocity bunching modulation when taking an ocean scene. The nonlinearity induced by the velocity bunching mechanism has a relationship between the azimuth gradient of radial current and the range-to-velocity ratio (R/V). The influence of velocity bunching modulation on shallow sea topography imaged by ATI-SAR is analyzed by taking a kind of shallow sea topography with a slope in azimuth direction as an example in this paper. The simulation results indicate that the interferometric phase of the shallow sea topography will be compressed, stretched or even overlapped according to the magnitude and direction of the azimuth gradient of radial current. Furthermore, the higher the ratio of R/V, the more serious distortion of the ATI-SAR.%通过理论推导,证明了顺轨干涉SAR对海洋成像时同普通SAR一样,存在速度聚束调制.速度聚束调制使得顺轨SAR对海洋成像时产生一种非线性映射关系,这种非线性映射关系与径向流场的方位向梯度变化以及平台到目标的斜距与平台运动速度的比值(R/V)有关.以方位向存在一定坡度的浅海地形为例,分析了速度聚束调制对顺轨干涉SAR浅海地形成像的影响.仿真结果分析表明:当径向流场在方位向上存在梯度变化时,根据梯度变化的大小和方向的不同,会使浅海地形特征在顺轨干涉SAR相位图像上产生压缩、拉伸甚至混叠等失真,且R/V越大失真越严重.