Temporal-Spatial Varying Background Ionospheric Effects on the Moon-Based Synthetic Aperture Radar Imaging: A Theoretical Analysis
Temporal-Spatial Varying Background Ionospheric Effects on the Moon-Based Synthetic Aperture Radar Imaging: A Theoretical Analysis
复制标题
时空变化背景电离层对月基合成孔径雷达成像的影响：理论分析
DOI：
10.1109/access.2018.2853163
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发表时间：
2018
期刊：
影响因子：
3.9
通讯作者：
Chen Kun-Shan
中科院分区：
文献类型：
--
作者：
Xu Zhen;Chen Kun-Shan
月基合成孔径雷达（SAR）具有前所未有的高时间分辨率和大空间覆盖能力，可用于对地观测。然而，月球-SAR-地球运动的复杂几何关系，在地球自转和月球公转的共同作用下，对信号处理和成像提出了很大的挑战。此外，低轨SAR成像中通常假设的电离层冻结模型不再适用于月基SAR，超长合成孔径时间导致的弯曲轨道使背景电离层效应更加复杂，从而使背景电离层效应对相位色散的影响变得更加严重。本文通过建立精确的弯曲轨道信号模型，研究了这种影响对月基SAR成像的影响。详细分析了电离层背景时空变化引起的像移和像散焦。数值分析表明，距离偏移可达数百米，而方位偏移要小得多，在几十米的数量级。至于图像质量，距离散焦持续显著，而方位聚焦仅受到轻微干扰。在存在背景电离层的情况下，在图像质量方面，应特别注意引起月基合成孔径雷达的几何失真和图像散焦。
The Moon-based synthetic aperture radar (SAR) potentially offers an unprecedented high temporal resolution and wide spatial coverage, simultaneously, for earth observation. However, the complex geometry in relating Moon-SAR-Earth motion, where both the earth’s rotation and lunar revolution exert, poses a great challenge in signal processing and image formation. Besides, the background ionospheric effects contributing to the phase dispersion become even more critical because the ionospheric freezing model usually assumed in the low earth orbit SAR imaging is no longer valid for the Moon-based SAR, and the curved trajectory induced by the ultra-long synthetic aperture time further complicates the background ionospheric effects. In this paper, we investigate such effects on the Moon-based SAR imaging by establishing an accurate curved trajectory signal model. The image shift and image defocus caused by the temporal–spatial varying background ionosphere are evaluated in detail. Numerical analysis shows that the range shift can be up to hundreds of meters, while the azimuth shift is much less, on the order of tens of meters. As for image quality, the range defocusing is persistently significant, and yet the azimuth focusing is only slightly disturbed. Under the presence of background ionosphere, the geometric distortion and image defocusing given rise to a Moon-based SAR deserve a special care in the context of image quality.
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DOI：
10.2478/v10018-007-0005-5
发表时间：
2006
期刊：
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影响因子：
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作者：
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通讯作者：
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DOI：
10.1007/s11430-013-4714-2
发表时间：
2014-05
期刊：
Science China Earth Sciences
影响因子：
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DOI：
10.1109/taes.2010.5545172
发表时间：
2010-08
影响因子：
4.4
作者：
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通讯作者：
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影响因子：
2.2
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影响因子：
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作者：
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