基于IMU的机载TOPSAR目标定位方法

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25 m的平均定位精度。

Target geo-location method in airborne TOPSAR mode based on IMU

In the terrain observation by progressive scans synthetic aperture radar (TOPSAR) mode, the application of burst mode and beam steering in the azimuth can effectively weaken scalloping effect, which is an inherent defect in ScanSAR mode. In addition, several problems arise in TOPSAR mode, such as the complex relationship between image pixels and the corresponding echo pulses, which makes it difficult to geo-locate targets precisely. Meanwhile, time-lapse in the process of recording inertial measurement unit (IMU) data will worsen the location accuracy in azimuth and precise estimation of the error will greatly improve geo-location performance. Proceeding from the geometric relationship of data acquisition and imaging algorithm in TOPSAR mode, a new target geo-location method is proposed with the usage of airborne IMU data. The presented method can provide longitude and latitude information of targets from processed imagery. Tests have been conducted using airborne TOPSAR imagery to verify the proposed method and average geo-location accuracy of twenty-five meters can be obtained.