分布式全相参雷达参数估计及ISAR成像方法研究

发布时间：2018-01-09 02:15

本文关键词：分布式全相参雷达参数估计及ISAR成像方法研究　出处：《北京理工大学》2015年博士论文　论文类型：学位论文

【摘要】：随着航空航天技术的快速发展，全球空间竞争日趋激烈，军事力量呈现空天一体化趋势。空天目标的探测、识别以及监视在未来空间攻防对抗中起着至关重要的作用。分布式全相参雷达具有探测威力强、时空分辨率高的优势，满足当前远程雷达的战术机动性需求，且制造工艺相对简单、成本低，是当前空间监视雷达的重要发展方向。虽然分布式相参雷达已实现原理验证，但当前仍处于初期发展阶段，尚存在不少关键技术问题有待研究与改善。本论文研究的分布式全相参雷达采用频率步进波形作为基本发射波形，发射单元集中式部署以实现发射相参，接收单元分布式部署以实现高分辨的分布式逆合成孔径雷达(ISAR)成像。针对该分布式全相参雷达体制，主要对其中的关键问题分布式全相参与分布式ISAR高分辨成像进行了深入的研究与探讨，主要的研究内容概述如下： 1.研究了基于频率步进宽带波形的分布式全相参雷达信号建模及相参性能分析。建立了基于频率步进波形的全相参雷达信号模型，包括接收相参参数估计模型与发射相参误差信号模型；基于接收相参参数估计模型，详尽地推导了相参参数的克拉美罗界（CRLB），分析发现频率步进波形具有实现高精度相参参数估计的潜力；基于发射相参误差模型，详尽地分析了频率步进波形下实现发射相参的参数估计精度需求；此外，还对发射相参对发射单元的几何配置约束进行了分析；最终，结合估计精度需求与CRLB，对基于频率步进宽带波形的分布式雷达实现全相参的信噪比要求进行了仿真分析，这对分布式相参雷达的设计与实现具有了重要的指导意义。 2.研究了基于频率步进波形的分布式雷达相参参数估计方法。建立了频率步进波形的高分辨距离像重建模型，分别提出了基于相关系数后向投影与最小二乘估计的高分辨距离像重建方法，分析了两种重建方法对频率步进间隔的无模糊约束条件，并通过仿真验证了提出的两种距离像重建法的有效性与可行性；此外，针对分布式雷达的相参参数估计问题，分别提出了基于包络熵快速相关的相参延时差估计方法以及基于包络相关粗估计与精搜索相结合的相参相位估计方法。最终通过仿真验证了提出方法在精度与效率方面的估计性能，，为实现发射相参以及分布式ISAR高分辨成像提供了支撑。 3.研究了基于图像熵的分布式相参ISAR高分辨成像方法。建立了广义的分布式ISAR成像信号模型，理论推导了双基地ISAR成像平面与回波数据关系；针对平动补偿中的距离包络对齐与平动相位校正问题，提出了熵准则下基于二次逼近迭代原理的参数寻优方法，实现了鲁棒的包络对齐以及精确的平动相位校正。其中，距离对齐方法还采用了循环级联滤波处理的方法，克服了局部极值造成的全局最优收敛问题，并采用仿真与实测数据验证了提出迭代估计方法的鲁棒性与精确性；针对双基地ISAR图像重建，提出了基于ISAR后向投影的转动中心与角速度估计方法，获得各子天线单元成像的投影几何关系，解决了回波数据的空间对齐问题，从而实现了各接收单元在同一空间坐标系下的ISAR图像重建；最终，基于各重建ISAR图像，进行了接收相参处理，实现了分布式全相参ISAR的高分辨图像融合，并通过仿真验证了提出方法的有效性，证明了提出方法可以为目标识别提供高分辨信息。
[Abstract]:With the rapid development of aerospace technology, global competition is becoming increasingly fierce, military power has the tendency of air and space integration. Space target recognition and detection, monitoring plays an important role in future space attack defense confrontation. Distributed coherent radar detection has strong power, high spatial and temporal resolution advantage, meet the remote radar tactical mobility the demand, and the manufacturing process is relatively simple, low cost, is an important development direction of current space surveillance radar. Although distributed coherent radar has been implemented to verify the principle, but the current is still in the early stage of development, there are still many problems to be studied and improved. The key technology
This paper studies the distributed coherent radar using stepped frequency waveform as the basic waveform, transmission unit of centralized deployment in order to achieve coherent emission and receiving unit to realize the distributed deployment of distributed high resolution inverse synthetic aperture radar (ISAR) imaging. According to the distribution of full coherent radar is one of the key issues of distributed phase in distributed ISAR conducted in-depth research and discussion of high resolution imaging, the main research contents outline as follows:
1. the analysis of distributed step frequency wideband waveform coherent radar signal modeling and performance. Based on a coherent coherent radar signal model of step frequency waveform based on coherent emission model and includes the error signal model to estimate the parameter estimation model based on coherent receiver; receiving phase parameters, detailed derivation of coherent parameters Clarke Meiluo circle (CRLB), analysis found that the stepped frequency is to achieve high accuracy of parameter estimation of coherent potential waveform; coherent emission error model based on the detailed analysis of the stepped frequency waveform to achieve emission parameters parameter estimation accuracy requirements; in addition, the emission of coherent emission unit geometric configuration constraints are analyzed; finally, combined with the estimation accuracy requirement and CRLB of distributed radar based on stepped frequency waveform to achieve broadband coherent SNR requirements are simulated and divided It is of great significance to the design and implementation of distributed coherent radar.
2. study on the estimation method of distributed radar parameters of step frequency waveform based on stepped frequency waveform is established. The high resolution range profile reconstruction model, are proposed to estimate the projection and least squares based on correlation coefficient after high resolution range image reconstruction method, fuzzy constraints analysis of two kinds of reconstruction methods in the frequency interval the two step, and proposed the effectiveness and feasibility of image reconstruction method is verified by simulation; in addition, for the problem of estimating the parameters of the distributed coherent radar, respectively, a method is proposed to estimate the coherent phase envelope entropy fast correlation parameter estimation method based on delay and envelope correlation coarse estimation and fine search based on the combination of. Finally through the simulation shows that the proposed method estimates the performance in terms of accuracy and efficiency, to achieve the emission of coherent and distributed ISAR imaging provides high resolution Support.
3. the study of the high resolution imaging method based on ISAR distributed coherent image entropy is established. The distributed ISAR imaging signal model is generalized, theoretical derivation of the bistatic ISAR imaging plane and echo data; for motion compensation in the distance alignment and translational phase correction, two parameter iteration optimization method based on principle put forward the entropy, to achieve robust and precise alignment of the translational phase correction. The range alignment method also adopts the method of cyclic cascade filtering, to overcome the global convergence problem caused by the local extremum, and the proposed iterative estimation of robustness and accuracy of the method used for simulation and measured data; bistatic ISAR image reconstruction based on ISAR is put forward after the projection of center of rotation and the angular velocity estimation method, the antenna unit projection imaging The geometric relationship between the solution space alignment problem of echo data, so as to realize the ISAR image reconstruction of each receiving unit in the same space coordinates; finally, the reconstruction of ISAR image based on the received coherent signal processing, realize the distributed coherent ISAR high resolution image fusion, and verify the effectiveness of the method through the simulation result shows that the proposed method can provide high resolution information for target recognition.

【学位授予单位】：北京理工大学
【学位级别】：博士
【学位授予年份】：2015
【分类号】：TN957.52

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