卫星导航系统中高性能干扰抑制新方法研究及实现

发布时间：2018-01-31 08:10

本文关键词： 导航抗干扰采样矩阵求逆空时结构 FPGA实现　出处：《电子科技大学》2014年硕士论文　论文类型：学位论文

【摘要】：全球卫星导航系统在民用领域的普及程度越来越高,在军事领域的重要性更是日益凸显,但同时由自身脆弱性所导致的极易受到人为干扰破坏的问题也很严重。改善卫星性能和排布方式虽然是最有效的抗干扰手段,但成本过高而且耗时很长,因此利用软件无线电技术在接收终端进行干扰抑制是目前的主流方向。本文在这样的背景下对基于阵列信号处理的接收终端抗干扰技术及其硬件实现进行了研究和分析。功率倒置是基于阵列的导航抗干扰中最常用的方法之一,基于功率倒置的权值更新算法较多,其中LMS(最小均方误差)算法因其在实现时运算量较小而成为工程首选,但是LMS也存在着自身无法回避的缺陷。本文在此基础上详细介绍了另外一种计算权值的方法即SMI(采样矩阵求逆)算法,最后通过仿真将它与LMS算法在纯空域和空时结构下的性能进行了对比。仿真结果说明,LMS算法的收敛性能对自相关矩阵特征值的分布十分敏感,而SMI算法则可以有效地克服这个问题;SMI的空时结构能够在一定程度上改善卫星信号和干扰信号来向靠近时的信号损失问题。在算法分析的基础上,本文基于一个集成Stratix II系列FPGA芯片的导航接收机前端首先介绍了AD变换以后的数字域处理流程,然后给出了纯空域SMI算法的FPGA实现方案,并利用实测数据进行了设计中各模块功能的仿真验证。最后进行外场实验,通过信号源远场发射干扰信号,有规律地改变干扰发射类型和发射功率,通过采集片上实时数据进行频谱分析的方法验证空域SMI算法的干扰抑制性能。在空域算法实现的基础上,本文通过接收机内嵌的型号为OMAP_L138的DSP芯片制定了空时二维SMI算法的FPGA和DSP联合实现方案,并着重介绍了该方案中FPGA定点运算部分各模块的实现流程,通过实测数据进行了ModelSim仿真验证。最后采取与空域相同的外场实验手段,通过采集实时数据进行空时二维SMI算法的干扰抑制性能的分析,并与纯空域进行了对比。
[Abstract]:The global satellite navigation system is becoming more and more popular in the civilian field, and the importance of the global satellite navigation system in the military field is becoming more and more prominent. But at the same time, the vulnerability caused by human interference caused by the problem is also very serious. Improving satellite performance and layout is the most effective anti-jamming means, but the cost is too high and time-consuming. So it is the mainstream direction to use the software radio technology to suppress the interference at the receiving terminal. In this paper, the anti-jamming technology and its hardware implementation of the receiving terminal based on array signal processing are studied in this paper. Power inversion is one of the most common methods in array based navigation anti-jamming. There are many weight updating algorithms based on power inversion, among which LMS (least mean Square error) algorithm is the first choice because of its small operation time. However, LMS also has its own defects. On this basis, this paper introduces another method to calculate the weight of the SMI (sampling matrix inverse) algorithm in detail. Finally, the simulation results show that the convergence performance of LMS algorithm is sensitive to the distribution of eigenvalues of autocorrelation matrix. The SMI algorithm can overcome this problem effectively. The space-time structure of SMI can improve the loss problem of satellite signal and interference signal when approaching to a certain extent. This paper introduces the digital domain processing flow after AD transform based on the front end of navigation receiver based on an integrated Stratix II series FPGA chip. Then, the FPGA implementation scheme of pure spatial SMI algorithm is given, and the function of each module is simulated with the measured data. Finally, the external field experiment is carried out, and the interference signal is transmitted by the signal source in the far field. The interference emission type and power are changed regularly, and the interference suppression performance of the spatial SMI algorithm is verified by collecting the real-time data on the chip for spectrum analysis, based on the implementation of the spatial algorithm. In this paper, the FPGA and DSP implementation scheme of space-time two-dimensional SMI algorithm is developed based on the DSP chip with OMAP_L138 embedded in the receiver. The realization flow of each module of FPGA fixed-point operation in this scheme is introduced emphatically, and the ModelSim simulation verification is carried out through the measured data. Finally, the same external field experimental means as in airspace is adopted. The interference suppression performance of space-time two-dimensional SMI algorithm is analyzed by collecting real time data and compared with pure spatial domain.
【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】：TN967.1

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