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Burst工作模式和方位波束的主动扫描使得TOPSAR工作模式能够有效削弱ScanSAR模式的扇贝效应,同时也导致图像方位向像素位置与回波脉冲的关系变得复杂,给目标定位带来了很多问题。惯性测量单元(IMU)数据记录延时也会导致方位向定位误差存在,精确估计这个误差能够大大提高目标的方位向定位精度。从TOPSAR数据采集的几何关系和成像过程出发,结合机载IMU数据,提出了一种新的机载TOPSAR目标定位方法。该方法能够直接从TOPSAR斜距图像中获取目标的经纬度信息。通过实际飞行试验获取的机载TOPSAR数据验证了该方法的有效性,能够获取25m的平均定位精度。
The active scanning of Burst working mode and azimuth beam makes TOPSAR working mode effectively weaken the scallop effect of ScanSAR mode and complicates the relationship between azimuth pixel position and echo pulse. It brings many problems for target localization. Inertial Measurement Unit (IMU) data recording delay can also lead to azimuth positioning error exists, accurate estimation of this error can greatly improve the target’s azimuth positioning accuracy. Based on the geometrical relationship and imaging process of TOPSAR data acquisition, a new airborne TOPSAR target location method is proposed based on the airborne IMU data. The method can obtain the longitude and latitude information of the target directly from the TOPSAR slant range image. The on-board TOPSAR data obtained from actual flight tests verify the effectiveness of this method and achieve an average positioning accuracy of 25 m.