星载干扰抑制技术研究及实现

发布时间：2018-03-03 22:38

本文选题：模数结合　切入点：旁瓣对消　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：随着卫星技术的发展,卫星通信抗干扰受到各国的重视,如今已经成为抗干扰研究的一个热点话题。某型号卫星通信系统使用了相控阵天线技术,通过控制阵列方向图主瓣指向,加强有用信号,提高通信效果。现在为了增强系统对抗从阵列方向图旁瓣进入的压制式干扰信号的能力,在尽量小改动原系统结构的前提下,采用了一种模数结合的旁瓣对消方法对系统加以改进。本文主要内容就是在一个简化系统上对这种模数结合的旁瓣对消方法进行设计和实现,检验此方法的性能,为其能否应用到实际卫星通信系统提供参考。文中首先针对相控阵介绍了有关自适应波束形成的相关理论,包括波束形成的原理、准则和实现算法,并对旁瓣对消方法的原理进行了详细介绍,为后文中模数结合旁瓣对消方法的理论和实现奠定基础。然后介绍了模数结合旁瓣对消方法的具体实现方案,给出了实验所用系统的硬件结构,分析了系统的工作原理。该方法把系统分为了模拟端和数字端两个部分,在数字端利用一种无阻塞矩阵旁瓣对消方法计算干扰抑制权值,并通过迭代的方法使其靠近系统的最优权值;在模拟端则将数字端求解的权值作用到一个由数字衰减器和数字移相器构成的幅相加权模块上,在信号射频段直接进行干扰抑制。之后,针对文中的模数结合旁瓣对消方法进行了一系列仿真。比较了无阻塞矩阵旁瓣对消和常规的旁瓣对消方法性能,说明设计中采用前者的原因;验证了文中权值迭代方法的正确性,并研究了迭代方法的收敛性;分析了权值求解算法的性能,选择一种SMI和LMS结合算法作为数字端权值计算的具体方法;讨论了实现过程中衰减器和移相器性能对干扰抑制效果的影响。最后对系统数字信号处理部分在FPGA中的具体实现做了详细介绍,给出包括信号去直流、数字下变频、系统干扰检测、SMI和LMS联合求解权值、权值转换和RS-232接口数据传输各模块的实现方案和对应的Modelsim仿真结果。并最终到实际系统上进行了测试,验证了此模数结合旁瓣对消方法对干扰抑制的有效性。
[Abstract]:With the development of satellite technology, the anti-jamming of satellite communication has been paid more and more attention by many countries, and it has become a hot topic in the research of anti-jamming. A certain type of satellite communication system uses phased array antenna technology. By controlling the direction of the main lobe of the array pattern, the useful signal is strengthened and the communication effect is improved. Now, in order to enhance the system's ability to resist the suppressed interference signal coming from the sidelobe of the array pattern, the original system structure is changed as little as possible. An analog-to-digital sidelobe cancellation method is used to improve the system. The main content of this paper is to design and implement this analog-to-digital sidelobe cancellation method on a simplified system, and to test the performance of this method. This paper first introduces the theory of adaptive beamforming for phased array, including the principle, criterion and implementation algorithm of beamforming. The principle of sidelobe cancellation method is introduced in detail, which lays a foundation for the theory and realization of modular combined sidelobe cancellation method, and then introduces the concrete realization scheme of modular combined sidelobe cancellation method. The hardware structure of the system used in the experiment is given, and the working principle of the system is analyzed. The system is divided into two parts, the analog end and the digital end. In the digital end, a non-blocking matrix sidelobe cancellation method is used to calculate the interference suppression weight. The iterative method is used to make it close to the optimal weight value of the system. At the analog end, the weights solved by the digital terminal are applied to a amplitude-phase weighting module composed of digital attenuators and digital phase shifters. The interference suppression is carried out directly in the radio frequency segment of the signal. Then, a series of simulations are carried out for the analog-to-digital sidelobe cancellation method in this paper. The performance of the non-blocking matrix sidelobe cancellation method and the conventional sidelobe cancellation method are compared. The reason why the former method is used in the design is explained, the correctness of the iterative method is verified, and the convergence of the iterative method is studied, and the performance of the algorithm is analyzed. A combination algorithm of SMI and LMS is chosen as the concrete method to calculate the digital end weight. The influence of the performance of attenuator and phase shifter on the effect of interference suppression is discussed. Finally, the realization of digital signal processing in FPGA is introduced in detail, including signal de-DC, digital downconversion, etc. The system interference detection and LMS solve the weight value, the weight conversion and the data transmission module of RS-232 interface and the corresponding Modelsim simulation results. Finally, the system is tested on the actual system. The effectiveness of this method combined with sidelobe cancellation for interference suppression is verified.
【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】：TN927.2

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