FMCW SAR成像与动目标检测方法

发布时间：2019-03-21 17:47

【摘要】：调频连续波(Frequency Modulated Continuous Wave,FMCW)合成孔径雷达(Synthetic Aperture Radar,SAR)不仅具有全天时、全天候和高分辨率等优点,而且具有重量轻、体积小、造价低和功耗低等特点,因此,FMCW SAR适装于多种探测平台上,甚至是小型无人机平台,它在战场侦查等军事应用和资源遥感等民用中都具有重要的应用前景。同时,FMCW SAR系统通常采用连续发射信号和Dechirp接收体制,平台的运动不能忽略,传统脉冲式SAR体制中的“停-走-停”假设不再成立,其回波形式更为复杂,需要对FMCW SAR回波信号进行分析,研究相应的FMCW SAR成像和动目标检测算法。因此,FMCW SAR成像与运动检测方法研究是目前雷达信号处理的研究热点和难点,该方向研究具有重要的理论意义和应用价值。本文首先建立FMCW SAR回波信号模型,研究了斜视模式下的FMCW SAR成像算法。其次,建立FMCW SAR动目标检测的回波模型,论述了FMCW SAR动目标检测方法。然后,考虑到广域运动目标显示(Ground Moving Target Indication,GMTI)具有观测区域广、重访率高且对分辨率要求不高等特点,可以完成对观测场景的快速监视与侦查,是目前地面目标检测技术的研究重点,因此,本文对FMCW SAR体制下广域GMTI处理算法进行深入研究。最后,本文通过仿真实验数据处理对相关的FMCW SAR成像与广域GMTI方法进行了验证,主要工作总结如下:(1)首先建立FMCW SAR的回波模型,详细分析了FMCW SAR的信号特点和雷达工作原理,并阐述了FMCW SAR与脉冲式SAR的差别;然后,分析斜视下FMCW SAR的信号特性,提出一种有效的斜视FMCW SAR成像算法;最后,利用仿真实验验证了该算法的有效性。(2)建立FMCW SAR动目标检测的回波模型,对动目标信号进行分析,结合多普勒频移补偿和DPCA技术等对动目标进行检测和粗成像,将动目标信息进行提取,并反变换到其原始数据,进行二次成像聚焦处理,通过基于多普勒频移补偿、方位去斜、模糊数估计和Keystone变换等联合处理方法,获取聚焦良好的动目标成像结果。并通过仿真实验验证了该动目标检测与成像方法的有效性。(3)首先建立FMCW广域GMTI动目标信号模型,深入地分析FMCW-DBS成像原理及成像条件。其次,利用DBS成像技术获得各波位的目标成像结果,并对各波位子图像进行基于快速相关法的图像拼接和坐标转换处理;接着,通过偏置相位天线(Displaced Phase center Anenna,DPCA)和恒虚警率(Constant False-Alarm Rate,CFAR)技术完成杂波抑制和动目标的检测;然后,利用干涉相位法完成动目标的角域定位,并将定位结果标定在上述成像结果中。最后,利用仿真数据处理验证该方法的有效性。
[Abstract]:FM CW (Frequency Modulated Continuous Wave,FMCW (Synthetic Aperture Radar,SAR) not only has the advantages of all-weather, all-weather and high resolution, but also has the characteristics of light weight, small size, low cost and low power consumption. FMCW SAR is suitable for a variety of detection platforms, even small unmanned aerial vehicles (UAVs). It has an important application prospect in military applications such as battlefield investigation and remote sensing of resources and other civilian applications. At the same time, the, FMCW SAR system usually adopts the continuous transmitting signal and the Dechirp receiving system, the motion of the platform cannot be ignored, the hypothesis of "stop-walk-stop" in the traditional pulse SAR system is no longer valid, and its echo form is more complicated. The FMCW SAR echo signal needs to be analyzed, and the corresponding FMCW SAR imaging and moving target detection algorithms are studied. Therefore, the research on, FMCW SAR imaging and motion detection is a hotspot and difficulty in radar signal processing at present, and the research in this direction has important theoretical significance and application value. Firstly, the FMCW SAR echo signal model is established, and the FMCW SAR imaging algorithm in squint mode is studied. Secondly, the echo model of FMCW SAR moving target detection is established, and the FMCW SAR moving target detection method is discussed. Then, considering that the wide-area moving object display (Ground Moving Target Indication,GMTI) has the characteristics of wide observation area, high revisit rate and low resolution, it can complete the rapid monitoring and investigation of the observation scene. It is the focus of research on ground target detection technology at present. Therefore, in this paper, the wide-area GMTI processing algorithm under the FMCW SAR system is deeply studied. Finally, the related FMCW SAR imaging and wide-area GMTI methods are verified by simulation data processing. The main work is summarized as follows: (1) first, the echo model of FMCW SAR is established. The signal characteristics of FMCW SAR and the working principle of radar are analyzed in detail, and the difference between FMCW SAR and pulse SAR is expounded. Then, the signal characteristics of FMCW SAR under squint are analyzed, and an effective squint FMCW SAR imaging algorithm is proposed. Finally, the validity of the algorithm is verified by simulation experiments. (2) the echo model of FMCW SAR moving target detection is established, the moving target signal is analyzed, and the moving target detection and coarse imaging are carried out by combining Doppler frequency shift compensation and DPCA technology. The moving target information is extracted and inversely transformed into its original data, then the secondary imaging focus processing is carried out. The joint processing methods are based on Doppler frequency shift compensation, azimuth declination, fuzzy number estimation and Keystone transform, etc. The imaging results of moving target with good focus are obtained. The effectiveness of the proposed method is verified by simulation experiments. (3) first, the FMCW wide-area GMTI moving target signal model is established, and the imaging principle and imaging conditions of FMCW-DBS are analyzed deeply. Secondly, the DBS imaging technology is used to obtain the target imaging results of each wave position, and the image stitching and coordinate conversion processing based on the fast correlation method are carried out for the image of each wave position. Secondly, clutter suppression and moving target detection are accomplished by bias phase antenna (Displaced Phase center Anenna,DPCA) and constant false alarm rate (Constant False-Alarm Rate,CFAR) techniques. Then, the interferometric phase method is used to locate the moving target in the angular domain, and the localization results are calibrated in the above imaging results. Finally, simulation data processing is used to verify the effectiveness of the proposed method.
【学位授予单位】：西安电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN957.52

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