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Focusing and Parameter Estimation of Fluctuating Targets in High Resolution Spaceborne SAR
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摘要: 高分辨率星载SAR图像中目标的复杂运动将引起不可忽视的散焦现象，影响目标识别和解译。该文对高分辨率星载SAR中目标起伏运动引入的误差进行了定量化分析，并仿真了其在SAR图像中的成像特点，提出了一种基于星载复图像数据进行运动误差补偿和精细聚焦处理的方法，同时估计得到目标的运动参数和海浪信息。仿真实验和TerraSAR-X港口区域实际数据实验验证了该方法的有效性和正确性。Abstract: Complex motion can cause serious defocusing phenomena in high resolution spaceborne SAR cases, which then lead to decreased image resolution. In this study, we built a simulation model to quantitatively analyze the signature and effect on maritime fluctuating targets in high resolution cases. To deal with formed Single-Look Complex (SLC) SAR images containing fluctuating targets, we implement a motion-compensation and fine-focusing method to obtain refocused images and the fluctuation parameters. We demonstrate the effectiveness and correctness of the proposed approach in focusing and estimating the parameters of fluctuating targets by processing the simulation results and archived images acquired by Terra-SAR in hybrid spotlight mode.
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Key words:
- Spaceborne SAR /
- High resolution /
- Moving target fine focusing /
- Parameter estimation
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图 6 散焦结果深采样后方位向波形
Figure 6. Azimuth responses for focusing results after deep sampling
图 7 起伏运动点目标单次散射精细聚焦结果
Figure 7. Fine focusing result for single scattering of fluctuating target
图 8 海面起伏点目标二次散射精细聚焦结果
Figure 8. Fine focusing result for double scattering of sea surface
图 11 图10(a)中某一亮线分析与处理结果
Figure 11. Analysis and processing results for certain light line inFig. 10(a)
图 12 TerraSAR-X旅顺码头数据分析与处理结果
Figure 12. Analysis and processing results for Lushun port from TerraSAR-X
表 1 雷达系统仿真参数
Table 1. Radar system simulation parameters
参数 数值 l 0.03112 m 带宽 650 MHz 采样率 750 MHz 场景中心最短斜距 755.651 km 合成孔径时间 4.1 s PRF 6800 下视角 –30.849° 入射角 –34.34° 距离向分辨率 0.2 m 方位向分辨率 0.4 m 
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表 2 参数估计结果
Table 2. Estimating results
参数估计及误差 起伏运动单次散射 海面起伏二次散射 Ae 0.106 m 0.103 m Te 3.999 s 4.012 s $\left| {\frac{{A_{\rm e} - A}}{A}} \right|$ 6% 3% $\left| {\frac{{T_{\rm e} - T_{\rm v}}}{{T_{\rm v}}}} \right|$ 0.025% 0.3%
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表 3 TerraSAR-X旅顺岛参数表
Table 3. Parameters for TerraSAR-X
雷达参数 数值 雷达参数 数值 l 0.03112 m PRF 42300 带宽 300 MHz 下视角 38.799° 采样率 329.658 MHz 入射角 41.355° 景中心最短斜距 613.981 km 距离向分辨率 0.5 m 合成孔径时间 5.39 s 方位向分辨率 0.25 m
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