SAR-GMTI系统检测性能研究

发布时间：2018-05-31 20:52

本文选题：合成孔径雷达 + 运动目标检测　；参考：《西安电子科技大学》2014年硕士论文

【摘要】：合成孔径雷达地面运动目标检测(SAR-GMTI)系统在对观测场景进行二维高分辨率成像的同时还能检测场景中的运动目标,目前已经广泛应用于军用和民用领域。本文主要对SAR-GMTI系统的检测性能进行了研究,分析了影响检测性能的各个因素,并针对运动目标的散焦效应对系统检测性能造成的不利影响提出了改进的方法。SAR-GMTI系统的自由度比较低,系统的检测性能和参数估计性能不高,而MIMO雷达通过多天线同时发射和接收相互正交的信号,可以获得远多于天线个数的系统自由度。利用MIMO-SAR GMTI系统的高自由度特性可以显著提高SAR-GMTI系统的成像分辨率、目标检测能力等性能。本文的主要研究内容有以下几点:1.研究了SAR-GMTI系统检测概率的计算流程,对不同计算环节中涉及到的各个因素分别进行了分析,并说明了其对系统检测性能的影响。2.研究了运动目标的散焦效应。由于运动目标存在方位向速度,其成像结果会出现散焦,这会造成目标的能量分散,信杂噪比下降,因而不利于运动目标的检测。针对散焦造成的不利影响,本文利用传统的相位梯度自聚焦方法和最小熵法对运动目标进行重聚焦,可以使运动目标的能量分布更加集中,增加了信杂噪比,从而提高了系统的检测性能。并针对两种算法的优缺点进行了分析。3.研究了MIMO-SAR GMTI系统信号处理技术。将MIMO技术和SAR相结合,不仅可以解决SAR系统固有的高分辨率和宽观测条带之间的矛盾,而且还能获得更好的系统检测性能。MIMO-SAR系统在距离向发射载频不同的窄带信号,然后经频谱叠加合成大带宽信号,可以提高系统在距离向上的分辨率。由于MIMO-SAR GMTI系统自由度高于SAR-GMTI系统自由度,因而可以检测到更慢速或更弱小的目标。本文提出了一套完整的MIMO-SAR GMTI系统的数据处理方案,并且根据不同载频对应的可检测速度范围不同,解决了速度模糊和盲速问题,使得运动目标的参数估计更加准确。
[Abstract]:The synthetic Aperture Radar (SAR) ground moving target detection system (SAR-GMTI) can detect the moving targets in the scene as well as 2D high-resolution imaging, which has been widely used in military and civil fields. In this paper, the detection performance of SAR-GMTI system is studied, and the factors that affect the detection performance are analyzed. Aiming at the adverse effect of defocusing effect of moving target on the detection performance of the system, an improved method. The degree of freedom of SAR-GMTI system is relatively low, and the detection performance and parameter estimation performance of the system are not high. MIMO radar transmits and receives orthogonal signals simultaneously by multiple antennas, which can obtain much more system degrees of freedom than the number of antennas. The high degree of freedom characteristic of MIMO-SAR GMTI system can significantly improve the imaging resolution and target detection ability of SAR-GMTI system. The main contents of this paper are as follows: 1. In this paper, the process of calculating the detection probability of SAR-GMTI system is studied, the factors involved in different calculation links are analyzed respectively, and the influence of it on the detection performance of the system is explained. The defocusing effect of moving target is studied. Because of the azimuth velocity of the moving target, the imaging result will appear defocusing, which will cause the energy dispersion of the target and the decrease of the signal-to-noise ratio, which is not conducive to the detection of the moving target. In view of the adverse effects caused by defocusing, the traditional phase gradient autofocus method and minimum entropy method are used to refocus moving targets, which can make the energy distribution of moving targets more concentrated and increase the signal-to-noise ratio. Thus, the detection performance of the system is improved. The advantages and disadvantages of the two algorithms are analyzed. The signal processing technology of MIMO-SAR GMTI system is studied. The combination of MIMO and SAR can not only solve the contradiction between high resolution and wide observation bands inherent in SAR system, but also obtain better detection performance. MIMO-SAR system can transmit different carrier frequency narrowband signals in range direction. Then a large bandwidth signal is synthesized by spectrum superposition, which can improve the resolution of the system in the range up. Because the degree of freedom of MIMO-SAR GMTI system is higher than that of SAR-GMTI system, slower or weaker targets can be detected. In this paper, a complete data processing scheme for MIMO-SAR GMTI system is proposed. According to the different range of detectable velocities corresponding to different carrier frequencies, the problem of velocity blur and blind velocity is solved, which makes the parameter estimation of moving targets more accurate.
【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】：2014
【分类号】：TN957.52

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