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Coherence-Based Geosynchronous SAR Tomography Employing Formation Flying: System Design and Performance Analysis
IEEE Transactions on Geoscience and Remote Sensing ( IF 8.2 ) Pub Date : 2021-02-12 , DOI: 10.1109/tgrs.2021.3056209
Zhiyang Chen , Cheng Hu , Xichao Dong , Yuanhao Li , Weiming Tian , Stephen Hobbs

Coherence-based synthetic aperture radar (SAR) tomography (TomoSAR) exploits the complex coherences of SAR images to achieve 3-D imaging. Utilizing two-sensor spaceborne SAR formation flying to realize coherence-based TomoSAR has attracted increasing attention because temporal decorrelation-free interferograms can be constructed; therefore, TomoSAR has excellent potential for inverting the vertical structures of natural scenes such as forests and glaciers. However, low earth orbit (LEO) TomoSAR is disadvantaged by limited data and nonuniform sampling in the elevation direction. Geosynchronous (GEO) TomoSAR can overcome these limitations owing to its short revisit time of no more than 24 h. For the first time, this article discusses coherence-based TomoSAR exploiting GEO SAR formation flying. The benefits of GEO-formation coherence-based TomoSAR, including the low cost of slave satellites, rich data sets, and uniform sampling, are noted. The key problems of system design, including the formation design and data acquisition, are discussed. A formation design method based on the minimum along-track baseline is proposed that can realize uniform elevation sampling. The geometric correlation of a general SAR observation geometry is derived; on this basis, an optimal data acquisition method based on the optimal height measurement Cramer–Rao lower bound (CRLB) is proposed. Finally, the performance of GEO-formation coherence-based TomoSAR is analyzed; in particular, the ambiguity height in the altitude direction, the Rayleigh resolution in the altitude direction, and the theoretical optimal geometric correlation are evaluated. Finally, computer simulations validate the proposed formation design method, data acquisition scheme, and performance analysis formula.

中文翻译:

使用编队飞行的基于相干的地球同步 SAR 层析成像:系统设计和性能分析

基于相干的合成孔径雷达 (SAR) 断层扫描 (TomoSAR) 利用 SAR 图像的复杂相干性来实现 3-D 成像。利用双传感器星载SAR编队飞行实现基于相干的TomoSAR越来越受到关注,因为它可以构建无时间去相关的干涉图;因此,TomoSAR 在反转森林和冰川等自然场景的垂直结构方面具有极好的潜力。然而,低地球轨道 (LEO) TomoSAR 的劣势在于数据有限且在仰角方向采样不均匀。地球同步 (GEO) TomoSAR 可以克服这些限制,因为它的重访时间不超过 24 小时。本文首次讨论了利用GEO SAR编队飞行的相干TomoSAR。基于地理形成相干的 TomoSAR 的好处,包括从属卫星的低成本、丰富的数据集和统一的采样等。讨论了系统设计的关键问题,包括编队设计和数据采集。提出了一种基于最小沿航迹基线的编队设计方法,可实现均匀高程采样。推导出一般SAR观测几何的几何相关性;在此基础上,提出了一种基于最优高度测量Cramer-Rao下界(CRLB)的最优数据采集方法。最后,分析了基于GEO形成相干的TomoSAR的性能;特别是对高度方向的模糊高度、高度方向的瑞利分辨率和理论最优几何相关性进行了评估。最后,
更新日期:2021-02-12
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