Aperture-dependent motion compensation for airborne SAR with 0.1 m resolution
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摘要: 讨论了0.1 m分辨率机载合成孔径雷达(SAR,Synthetic Aperture Radar)运动补偿方案设计中的一个新问题.超高方位分辨率意味着长合成孔径和大相干积累角,条带模式下的回波数据中可能包含不可忽略的方位角度相关的残余运动误差.分析了这种运动误差孔径依赖性对机载SAR成像质量的影响,它将造成图像的几何失真和方位散焦.提出了一种基于子孔径数据处理的补偿方法,根据雷达瞬时照射时刻与多普勒频率之间的关联性对数据进行方位向上的分段和补偿,可以直接嵌入联合一阶运动补偿和二阶运动补偿的成像处理流程中.仿真结果表明此孔径依赖性运动补偿方法进一步改善了图像的聚焦质量.Abstract: A new technological problem in 0.1 m resolution airborne SAR(synthetic aperture radar) motion compensation design procedure was discussed. High azimuth resolution means large synthetic aperture length and wide integration angle, thereby echo data collected in stripmap mode might include remarkable residual motion errors related with azimuth angle between the radar and the target. The impact of platform aperture-dependent motion errors in stripmap mode on airborne SAR image quality was analyzed. It shows that the errors cause geometry distortion and azimuth defocusing. Based on the relation between radar instantaneous illuminate time and Doppler frequency, an aperture-dependent motion compensation approach was put forward to improve image quality. This method applies segmentation and compensation data in azimuth direction and enters into the processing scheme integrated with conventional motion compensation,the first order motion compensation and the second order motion compensation. Simulation results validate the whole analysis and the proposed procedure.
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Key words:
- airborne synthetic aperture radar /
- high resolution /
- motion compensation
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