圆迹SAR系统DEM提取及运动补偿技术研究

发布时间：2018-08-23 13:01

【摘要】：圆迹合成孔径雷达(Circular Synthetic Aperture Radar,CSAR)是一种具备三维重建能力的新型的遥感成像系统。在圆迹SAR模式下进行聚焦成像对场景目标高度具有依赖性,而且非理想航迹下,受运动误差的影响,圆迹SAR回波信号重建的图像聚焦质量下降,散焦不再仅沿着方位向存在,运动补偿的实现较为困难。为此,基于圆迹SAR系统特性本文先研究了圆迹SAR模式下场景DEM提取的方法,然后讨论了基于非均匀傅立叶变换(NUFFT)的圆迹SAR回波成像,并进而实现非理想航迹下,重建圆迹SAR图像的运动补偿。本论文主要研究工作如下所述:1)圆迹SAR模式下对场景DEM提取方法的研究。首先对高度误差条件下圆迹SAR全孔径和子孔径成像重建图像的相位误差进行理论分析。然后,研究了子孔径图像目标定位偏差与高度误差之间的关系,进而介绍了圆迹SAR模式下提取目标高度的算法原理,并获得整个场景的DEM信息。最后通过编程仿真实验验证了该算法的有效性。2)基于非均匀傅立叶变换(Non-Uniform Fast Fourier Transform,NUFFT)的圆迹SAR成像和运动补偿算法研究。针对传统成像算法插值会引起误差影响成像质量的缺陷,本文研究了一种基于NUFFT的圆迹SAR成像算法,能够减少旁瓣并提高成像质量。然后,分析了圆迹SAR运动误差模型,基于NUFFT对子孔径成像,并利用相位梯度自聚焦算法对每个子孔径图像进行运动误差估计,并补偿到每幅子孔径图像中,最后把补偿后的子孔径图像拼接成全孔径聚焦图像。通过编程仿真同样验证了该算法的可行性。
[Abstract]:Circular synthetic Aperture Radar (Circular Synthetic Aperture) is a new remote sensing imaging system with 3D reconstruction capability. Focusing imaging in circular track SAR mode is dependent on the height of scene target, and under the influence of motion error, the focus quality of image reconstructed by circular track SAR echo signal decreases, defocusing does not exist only along azimuth direction. The realization of motion compensation is difficult. Therefore, based on the characteristics of circular trace SAR system, this paper first studies the method of scene DEM extraction in circular SAR mode, then discusses the circular trace SAR echo imaging based on non-uniform Fourier transform (NUFFT), and then realizes the non-ideal track. Motion compensation of reconstructed circular SAR images. The main work of this thesis is as follows: 1) the research of scene DEM extraction method based on circular trace SAR mode. Firstly, the phase error of circular track SAR full aperture and subaperture reconstruction images is theoretically analyzed under the condition of height error. Then, the relationship between target positioning error and height error in sub-aperture image is studied, and then the algorithm principle of extracting target height in circular SAR mode is introduced, and the DEM information of the whole scene is obtained. Finally, the validity of the algorithm is verified by programming and simulation. 2) Research on circular SAR imaging and motion compensation algorithm based on Non-Uniform Fast Fourier transform. Aiming at the defect that the interpolation of traditional imaging algorithm will cause errors to affect the imaging quality, a circular track SAR imaging algorithm based on NUFFT is studied in this paper, which can reduce sidelobe and improve imaging quality. Then, the motion error model of circular track SAR is analyzed, and the motion error of each sub-aperture image is estimated by using phase gradient autofocus algorithm based on NUFFT, which is compensated to each sub-aperture image. Finally, the compensated sub-aperture image is spliced into a full aperture focusing image. The feasibility of the algorithm is also verified by programming simulation.
【学位授予单位】：南京邮电大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN957.52

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