星机双基地SAR同步技术研究

发布时间：2018-01-16 10:13

本文关键词：星机双基地SAR同步技术研究　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：本文的研究对象为星机双基地SAR(Spaceborne/Airborne Bistatic Hybrid SAR,SA-Bi SAR)系统,一种非对称体制双基地SAR系统,其结合了星载SAR系统覆盖面广、隐蔽性强和机载SAR系统机动灵活、分辨率高等优点,无论在军事或者民用领域,都有较高的研究和应用价值。以德国为代表的西方发达国家已经展开了一系列SA-Bi SAR系统试验,并取得了令人鼓舞的成果。然而,SA-Bi SAR系统要走向实用化仍面临诸多难题,同步问题便是其中之一。并且,由于非对称性,SA-Bi SAR系统的同步技术与对称体制双基地SAR系统有很大差别。目前,同步问题已成为SA-Bi SAR系统迈向实用化所面临的艰巨挑战。针对SA-Bi SAR系统的同步技术,本文展开了深入研究,主要工作如下:1.对SA-Bi SAR系统的主要技术参数进行了分析,这些技术参数包括:空间分辨率、信噪比、成像时间、场景长度、合成孔径时间和测绘带。并结合这些参数,对现有文献中提出的工作模式进行了分析。2.针对现有SA-Bi SAR系统空间同步方法的不足,提出基于多波束接收模式的空间同步方案。分析了SA-Bi SAR系统空间同步的必要性,给出了所提空间同步方案的理论推导和实现步骤,通过信噪比、场景长度和方位分辨率等性能参数与“双宽波束模式”进行了对比分析,验证了基于多波束接收的同步方法的有效性。同时,对由“事前误差”引起的成像场景偏移以及由“事中误差”引起的收发波束指向偏移进行了仿真,进一步证明了该空间同步方案的可行性。3.详细分析了时间同步误差的来源、模型以及影响。借鉴现有理论成果,设计了一种基于直达波的SA-Bi SAR系统时间同步方案,给出了方案的具体实现步骤。为提取线性时间误差漂移率,设计了一种高效的多普勒质心估计算法,适用于实时处理。最后,以基于2D-PSP的RD成像算法进行仿真,结果表明:经时间同步误差补偿后的成像性能有较大改善。4.详细分析了频率/相位同步误差的来源、模型以及影响。借鉴现有理论成果,设计了一种基于直达波的SA-Bi SAR系统频率/相位同步方案,给出了方案的具体实现步骤。为提取每一个脉冲对应的随机误差项,设计了一种估计基线距离的方法。最后,以基于2D-PSP的RD成像算法进行仿真,结果表明:经频率/相位同步误差补偿后的成像性能有较大改善。
[Abstract]:The research object of this paper is the bistatic SAR(Spaceborne/Airborne Bistatic Hybrid SAR-Bi SAR) system. An asymmetric bistatic SAR system combines the advantages of wide coverage, strong concealment, maneuverability and high resolution of an airborne SAR system, both in military and civilian fields. The western developed countries, represented by Germany, have carried out a series of SA-Bi SAR system tests and achieved encouraging results. SA-Bi SAR system still faces many problems to be practical, synchronization is one of them, and because of asymmetry. The synchronization technology of SA-Bi SAR system is very different from that of symmetrical bistatic SAR system. Synchronization has become a formidable challenge for SA-Bi SAR system to become practical. This paper has carried out a deep research on synchronization technology of SA-Bi SAR system. The main work is as follows: 1. The main technical parameters of SA-Bi SAR system are analyzed, including spatial resolution, signal-to-noise ratio, imaging time and scene length. Combined with these parameters, the working mode proposed in the existing literature is analyzed. 2. Aiming at the deficiency of the existing spatial synchronization method of SA-Bi SAR system. A spatial synchronization scheme based on multi-beam receiving mode is proposed, and the necessity of spatial synchronization in SA-Bi SAR system is analyzed. The theoretical derivation and implementation steps of the proposed spatial synchronization scheme are given, and the signal-to-noise ratio (SNR) of the proposed spatial synchronization scheme is given. Performance parameters such as scene length and azimuth resolution are compared with "double wide beam mode" to verify the effectiveness of the synchronization method based on multi-beam reception. The imaging scene offset caused by "prior error" and the transceiver beam pointing offset caused by "mid-incident error" are simulated. Furthermore, the feasibility of the spatial synchronization scheme is proved. 3. The source, model and influence of the time synchronization error are analyzed in detail. A time synchronization scheme for SA-Bi SAR system based on direct wave is designed, and the implementation steps are given. The linear time error drift rate is extracted. An efficient Doppler centroid estimation algorithm is designed, which is suitable for real-time processing. Finally, the Rd imaging algorithm based on 2D-PSP is simulated. The results show that the imaging performance after compensation of time synchronization error is greatly improved. 4. The source, model and influence of frequency / phase synchronization error are analyzed in detail. A frequency / phase synchronization scheme for SA-Bi SAR system based on direct wave is designed, and the implementation steps are given. The random error terms corresponding to each pulse are extracted. A method of estimating baseline distance is designed. Finally, the Rd imaging algorithm based on 2D-PSP is simulated. The results show that the imaging performance is improved greatly after the frequency / phase synchronization error is compensated.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN958

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