Abstract
Imaging position shift based on the multiple azimuth squint angles (MASA) mode is effective for target azimuth velocity estimation, whereas accuracy is low when target range velocity is high. In this paper, the estimation problem for both target azimuth and range velocities is considered based on the multi-channels MASA (MC-MASA) mode. Firstly, the acquisition geometry of MC-MASA mode and Doppler characteristics of a moving target are analyzed in detail, especially in squint mode. Then, for better moving target estimation, the stationary background clutter is removed using the displacement phase center antenna (DPCA) technique, and the failure in range velocity estimation with sequential SAR images is also discussed. Furthermore, a modified along-track interferometry (ATI) is proposed to preliminarily reconstruct the azimuth-and-range velocity map based on the MC-MASA mode. Since the velocity estimation accuracy is dependent on squint angle and signal-to-clutter ratio (SCR), the circumstances are divided into three cases with different iteration estimation strategies, which could expand the scene application scope of velocity estimation and achieve a high estimation accuracy along both azimuth and range directions. Finally, the performance of the proposed method is demonstrated by experimental results.
Highlights
Ground moving target indication (GMTI) and track formation have received growing attention in both civilian and military applications [1,2,3], with the development of synthetic aperture radar (SAR) technique
Clutter energy is coherent in the integration time and the change of target energy leads to different values of signal-to-clutter ratio (SCR)
The designed experiment is mainly to verify the effectiveness of the combination method when method 1 and method 2 have large errors, so two targets belong to Case 2 and one is T3 corresponds to the worst situation in Case 1
Summary
Ground moving target indication (GMTI) and track formation have received growing attention in both civilian and military applications [1,2,3], with the development of synthetic aperture radar (SAR) technique. By interference processing using signals from different receiving channels, the residual phase is used for target range velocity estimation, whereas the detection performance eventually depends on the signal-to-clutter-plus-noise ratio (SCNR) To address this issue, detectors were constructed by combining amplitude and phase of ATI information [21,22]. MASA (MC-MASA) mode, which introduces multiple-channel receiving technique on MASA mode On this basis, the DPCA technique in azimuth squint-looking is introduced for background clutter remove, which has better performance on azimuth velocity estimation with sequential SAR images. In order to achieve a high target azimuth-and-range velocity map reconstruction accuracy even in some relatively complex situations, the circumstances are divided into three cases with different iterative strategies according to SAR acquisitions, i.e., iterative combinations of the method with moving target position shift among sequential SAR images and ATI interferometric method.
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