基于LFM-PC复合调制信号的SAR波形抗干扰技术研究

发布时间：2018-06-27 13:56

本文选题：合成孔径雷达 + LFM-PC信号　；参考：《南京航空航天大学》2017年硕士论文

【摘要】：合成孔径雷达(SAR)是一种主动式微波遥感系统,与光学成像相比,由于其不受光照和气候条件的影响,能实现全天时、全天候工作,因此在民用和军用领域都有广泛应用。欺骗式干扰通过较小的干扰功率就可以在SAR图像上生成虚假目标,是当前干扰技术中的研究重点。针对欺骗式SAR干扰,目前的抗干扰技术主要包括脉间信号参数捷变、脉间波形捷变等。常用雷达信号中,线性调频(LFM)信号自相关性能差,信号形式简单,易被干扰机识别,抗干扰性能差;相位编码信号和混沌类信号有很好的抗干扰性能,但是对多普勒敏感。基于上述背景,本文的主要研究内容如下:(1)利用相位编码信号调制LFM信号,得到了一种新的复合调制信号——LFM-PC信号。分析了该信号的距离向分辨率、多普勒容限和正交性。针对该信号对多普勒敏感的问题,采用序列二次规划(SQP)法优化模糊函数,增大其多普勒容限。讨论了基于LFM-PC信号和极坐标格式算法的SAR成像方法的可行性。(2)针对欺骗式SAR干扰,提出了一种基于正交LFM-PC波形捷变的抗干扰方法。通过在不同方位时刻发射相互正交的LFM-PC信号,使得干扰信号无法获得距离向脉压增益。基于极小化峰值旁瓣能量准则建立优化模型,采用SQP法设计正交LFM-PC波形。仿真验证了优化后的LFM-PC信号具有良好的正交性,且该方法取得了良好的抗干扰性能。(3)针对欺骗式SAR干扰,提出了一种方位向叠加自适应初相的抗干扰方法。采用共轭梯度法设计自适应初相,极小化待优化区域的方位向干扰幅度。针对上述方法在干扰幅度过大时造成的真实目标信息被压制的问题,提出了正交LFM-PC波形捷变和自适应初相结合的复合抗干扰方法,首先通过正交LFM-PC波形捷变使得干扰信号无法获得距离向脉压增益,再设计自适应初相极小化待优化区域的覆盖噪声干扰幅度。仿真验证了该方法具有良好的抗干扰性能。
[Abstract]:Synthetic Aperture Radar (SAR) is an active microwave remote sensing system. Compared with optical imaging, synthetic Aperture Radar (SAR) is widely used in civil and military fields because it is not affected by light and weather conditions and can work all day and all weather. Deceptive jamming can generate false targets on SAR images through small jamming power, which is the focus of current jamming technology. The current anti-jamming techniques for deceptive SAR jamming mainly include inter-pulse signal parameter agility, inter-pulse waveform agility and so on. Among the common radar signals, the linear frequency modulation (LFM) signal has poor autocorrelation performance, simple signal form, easy to be recognized by jammer, and poor anti-jamming performance. The phase coded signal and chaotic signal have good anti-jamming performance, but they are sensitive to Doppler. Based on the above background, the main contents of this paper are as follows: (1) A new composite modulation signal, LFM-PC signal, is obtained by modulating LFM signal with phase-coded signal. The range resolution, Doppler tolerance and orthogonality of the signal are analyzed. To solve the problem that the signal is sensitive to Doppler, the sequential quadratic programming (sqp) method is used to optimize the ambiguity function to increase its Doppler tolerance. The feasibility of SAR imaging method based on LFM-PC signal and polar format algorithm is discussed. (2) an anti-jamming method based on orthogonal LFM-PC waveform agility is proposed for deceptive SAR jamming. By transmitting orthogonal LFM-PC signals at different azimuth times, the interference signal can not obtain the range pulse compression gain. The optimization model is established based on the minimized peak sidelobe energy criterion and the orthogonal LFM-PC waveform is designed by sqp method. Simulation results show that the optimized LFM-PC signal has good orthogonality and good anti-jamming performance. (3) for deceptive SAR jamming, a new anti-jamming method based on azimuth superposition adaptive initial phase is proposed. The conjugate gradient method is used to design the adaptive initial phase to minimize the azimuth interference amplitude of the region to be optimized. In view of the problem that the real target information caused by the above methods is suppressed when the jamming amplitude is too large, a composite anti-jamming method combining orthogonal LFM-PC waveform agility and adaptive initial interference is proposed. First, the interference signal is unable to obtain the range pulse compression gain by orthogonal LFM-PC waveform agility, and then the adaptive initial phase minimization is designed to minimize the coverage noise interference amplitude of the region to be optimized. The simulation results show that the method has good anti-interference performance.
【学位授予单位】：南京航空航天大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN957.51

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