一种利用掩模法抑制杂波的GMTI方法
doi: 10.3724/SP.J.1146.2006.00001
A Novel GMTI Method Based on Masking Technique
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摘要: 该文研究了一种利用掩模抑制杂波的GMTI(Ground Moving Target Indication)方法。在该方法中利用子孔径对消形成动目标掩模。由于静目标在方位向两个子孔径中的表现相同而动目标不同，因此在该掩模上静目标被消掉，动目标的痕迹得以保留。利用此掩模与距离压缩方位未聚焦的复图像相乘，以恢复动目标的幅度和相位。乘积的复图像采用比静目标更宽频带的参考函数进行方位聚焦，并采用自聚焦的方法进一步聚焦，以提高信噪比和动目标的发现概率。该方法适合运动速度较大的目标，和ATI(Along-Track Interferometry)方法相结合可以有效增大动目标的速度检测范围。Abstract: A novel approach of Ground Moving Target Indication (GMTI) based on subapertures and masking is developed in this paper. At first, Range Compressed and Azimuth Unfocused (RCAU) complex SAR image is split into two subapertures symmetrically in azimuth. Due to different behaviors of moving target and stationary target between the two subapertutes, the stationary target can be canceled and the moving target can be reserved by subtraction between the subapertures. The trajectory of moving target can be recovered and a image mask can be formed from this difference image. The phase history of the moving target can be restored on this mask by multiplying with the RCAU complex image. Then, the moving target is focused with a wider Doppler band matched filter and refined with Phase Gradient Autofocus (PGA) to aggregate energy and enhance detection probability. Finally, the moving target is detected with a 2-D Constant False Alarm Rate (CFAR). Combined with Along-Track Interferometry (ATI) the approach can extend velocity range of moving target extensively.
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