高分辨率星载SAR成像与图像质量提升方法综述

李春升; 于泽; 陈杰

doi:10.12000/JR19085

高分辨率星载SAR成像与图像质量提升方法综述

DOI: 10.12000/JR19085

北京航空航天大学电子信息工程学院北京 100191

基金项目: 国家自然科学基金(61861136008)

详细信息

作者简介:
李春升(1963–)，男，天津人，北京航空航天大学，教授，博士生导师，主要从事星载SAR系统总体与仿真、多源遥感图像信息融合、信息获取与处理等方面的研究工作。E-mail: lichunsheng@buaa.edu.cn

于　泽(1979–)，男，博士，副教授，现任职于北京航空航天大学电子信息工程学院。分别于2002年、2007年在北京航空航天大学获得学士学位和博士学位。目前主要研究方向包括天基雷达系统体制设计、高分辨SAR成像处理、稀疏目标特征重建等。E-mail: yz613@buaa.edu.cn

陈　杰(1973–)，教授、博士生导师，长期从事高分辨率微波遥感信息系统理论与方法研究。2005年获得北京市高等教育成果二等奖，2006年入选教育部“新世纪优秀人才支持计划”，2008年获霍英东教育基金会第十一届高等院校青年教师奖三等奖。承担国家自然科学基金、“973”计划、“863”计划、国家重大专项等多项课题。已发表论文100余篇，其中SCI(E)检索15篇，EI检索80余篇。申请国家发明专利20余项，合作编写教材4部，合作出版译著1部。E-mail: chenjie@buaa.edu.cn

通讯作者:
李春升 lichunsheng@buaa.edu.cn

于泽 yz613@buaa.edu.cn

中图分类号: TN958
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出版历程
- 收稿日期: 2019-09-21
- 修回日期: 2019-11-30
- 网络出版日期: 2019-12-01

Overview of Techniques for Improving High-resolution Spaceborne SAR Imaging and Image Quality

School of Electronic and Information Engineering, Beihang university, Beijing 100191, China

Funds: The National Natural Science Foundation of China (61861136008)

More Information

Corresponding author: LI Chunsheng, lichunsheng@buaa.edu.cn; YU Ze, yz613@buaa.edu.cn

摘要

摘要: 作为一种重要的空间遥感信息获取工具，星载合成孔径雷达(SAR)具备高分辨率宽测绘、多方位信息获取、高时相对地观测、3维地形测绘等多种工作体制和模式。对于任何星载SAR系统，获取高质量的图像始终是提升SAR应用效能的前提。该文基于“观测在天，成像在地”的理念，分析了卫星轨道、平台姿态、有效载荷、地面处理等环节中星载SAR成像和图像质量的影响因素；阐释了中央电子设备幅相补偿与动态调整、天线方向图预估等高精度数据获取技术；给出了基于改进运动模型的星载SAR成像补偿和对流层传播效应补偿方法，能够实现优于0.3 m分辨率的成像；总结和对比了相干斑噪声抑制、方位模糊抑制和旁瓣抑制等SAR图像处理技术，可以使得等效视数优于25、方位模糊和旁瓣抑制优于20 dB。
- 星载合成孔径雷达 /
- 成像处理 /
- 图像处理 /
- 星地一体化
Abstract: As an important tool for acquiring remote sensing information, Synthetic Aperture Radar (SAR) has various modes, including high-resolution wide-swath, multi-angle information acquisition, high temporal observation, and three-dimensional topographic mapping. For any spaceborne SAR system, obtaining high-quality images is a prerequisite for improving the performance of SAR applications. In this paper, we analyze the factors affecting spaceborne SAR imaging and image quality with respect to orbit, platform, payload, and signal processing. We describe high-precision data acquisition techniques, including amplitude-phase compensation, the dynamic adjustment of the central electronic equipment, and antenna pattern estimation. We then present imaging compensation methods based on the improved motion model and tropospheric delay correction, which can achieve resolutions better than 0.3 m. Lastly, we summarize and compare SAR image processing techniques such as speckle noise suppression, azimuth ambiguity suppression, and sidelobe suppression, whereby the equivalent number of looks can be increased to more than 25 and the azimuth ambiguity and sidelobes can both be suppressed by 20 dB.
- Spaceborne Synthetic Aperture Radar /
- Imaging processing /
- Image processing /
- Satellite-terrestrial system integration

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图 1 星载SAR对地观测示意图

Figure 1. Observation geometry of spaceborne SAR

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图 2 星载SAR有效载荷基本结构示意图

Figure 2. Diagram of the basic structure of the spaceborne SAR payload

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图 3 MGC反演前后的成像结果

Figure 3. Imaging results before and after MGC inversion

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图 4 星载SAR天线系统优化和方向图预估技术示意图

Figure 4. Diagram of optimization and pattern estimation technology for spaceborne SAR antenna system

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图 5 停走误差补偿前后成像结果对比图

Figure 5. Comparison of imaging results before and after the compensation of stop-go phase error

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图 6 原始SAR图像和斑点噪声抑制后的结果

Figure 6. Results of speckle suppression

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图 7 方位模糊抑制效果

Figure 7. Azimuth ambiguity suppression result

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图 8 SVA处理结果

Figure 8. SVA result

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图 9 SAR图像质量提升方法总结

Figure 9. Summary of SAR image quality improvement methods

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表 1 实时定轨和事后定轨比较

Table 1. Comparison between real-time and precise orbit determination

	输入数据类型	数据时效性	定轨精度
实时定轨	广播星历+双频伪距载波观测数据	实时	米级
事后定轨	IGS最终产品+双频伪距载波观测数据	12–18天	厘米级

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表 2 通道误差补偿前后脉冲压缩性能

Table 2. Performance of pulse compression before and after compensating for channel error

幅相误差	分辨率(m)	展宽系数	峰值旁瓣比(dB)	积分旁瓣比(dB)
无补偿	0.2392	1.0800	–6.41	–5.85
补偿	0.2232	1.0077	–13.25	–9.97

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表 3 仿真参数

Table 3. Simulation parameters

参数	数值	参数	数值
轨道倾角	98.06°	波束宽度(方位向)	0.305°
轨道高度	680 km	斜视角	±6.21°
偏心率	0.001	信号带宽	1.0 GHz
观测视角	35°	脉冲宽度	40 μs
波长	0.03 m	脉冲重复频率	4000 Hz

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表 4 停走误差补偿前后成像质量评估结果

Table 4. Imaging quality evaluation of point target before and after compensating for stop-go error

		分辨率(m)	峰值旁瓣比(dB)	积分旁瓣比(dB)
距离向	补偿前	0.1444	–15.42	–12.51
距离向	补偿后	0.1342	–13.13	–9.80
方位向	补偿前	0.2420	–11.98	–9.79
方位向	补偿后	0.2170	–13.32	–10.41

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表 5 不同视角下目标对流层延迟补偿前后对比

Table 5. Evaluation results before and after tropospheric delay compensation with different looking angles

视角(°)	对流层延迟补偿前方位向性能			对流层延迟补偿后方位向性能
视角(°)	分辨率(m)	PSLR(dB)	ISLR(dB)	分辨率(m)	PSLR(dB)	ISLR(dB)
15	0.272	–12.448	–9.213	0.270	–13.246	–10.150
35	0.272	–12.033	–8.938	0.269	–13.223	–10.319
55	0.294	–8.579	–5.860	0.275	–13.240	–10.069

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表 6 斑点噪声抑制指标

Table 6. Speckle noise suppression performance

图像	ENL1	ENL2	EPI
图6(a)	0.9996	0.9682	–
图6(b)	36.3338	26.3064	0.9484
图6(c)	1.0420	1.0051	–
图6(d)	67.2727	36.5582	0.9480

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