Ground Moving Target Indication via Multichannel Airborne SAR

We consider moving target detection and velocity estimation for multichannel synthetic-aperture-radar (SAR)-based ground moving target indication (GMTI). Via forming velocity versus cross-range images, we show that small moving targets can be detected even in the presence of strong stationary ground clutter. Furthermore, the velocities of the moving targets can be estimated, and the misplaced moving targets can be placed back to their original locations based on the estimated velocities. An iterative adaptive approach, which is robust and user parameter free, is used to form velocity versus cross-range images for each range bin of interest. Moreover, we discuss calibration techniques to estimate the relative antenna distances and antenna gains in practical systems. Furthermore, we present a simple algorithm for stationary clutter cancelation. We conclude by demonstrating the effectiveness of our approaches by using the Air Force Research Laboratory publicly released Gotcha airborne SAR-based GMTI data set.

I. Introduction

Synthetic aperture radar (SAR) imaging has been widely used in many civilian and military applications [1], [2]. Since SAR was originally developed for imaging the stationary scene, a moving target is usually misplaced due to the motion-induced Doppler shift in the SAR image [3]–[6]. The goal of SAR-based ground moving target indication (GMTI) is twofold: detection of moving targets in the SAR images and parameter estimation, including velocity and location determination of the moving targets. This problem is rather challenging when the moving targets are slow and small and are buried in strong stationary ground clutter.