卫星导航系统中窄带干扰抑制技术研究与实现

发布时间：2017-12-28 16:01

本文关键词：卫星导航系统中窄带干扰抑制技术研究与实现　出处：《电子科技大学》2016年硕士论文　论文类型：学位论文

【摘要】：全球导航卫星系统(Global Navigation Satellite System,GNSS)通过全天候、不间断地播发导航信号,可实现对目标的实时定位、导航和监督管理。GNSS已深入应用于生产生活等多个领域。但在复杂的无线环境中,经过长距离地传输,卫星导航信号到达地面时已经很微弱。同时,导航信号还受到多种有意和无意的干扰,严重时使得接收机无法正常工作。窄带干扰就是一种常见的干扰。因此,需在接收机中加入窄带干扰抑制模块,以保证接收机的正常工作。在单天线接收导航信号的前提下,本文主要对时域和频域的窄带干扰抑制技术进行了深入研究,并在此基础上对时域LMS滤波器和频域的50%重叠加窗法频谱滤波器进行了实现。根据导航信号和窄带干扰在时域和频域中的不同特性,本文主要做了以下工作:(1)通过对接收机面临干扰种类的分析,对接收的导航信号和窄带干扰进行了建模,并根据模型对窄带干扰对接收机的影响进行了详细分析。(2)基于预测估计思想,在时域研究了导航信号的窄带干扰抑制技术。详细介绍了LMS(Least Mean Square)及其改进的变步长滤波器和LS(Least Squares)、LSL(Least Squares lattice)滤波器的基本原理,对各个滤波器的窄带干扰抑制性能进行了仿真对比。(3)介绍了频域窄带干扰抑制的基本原理,并对其中涉及模块的相关算法进行了深入研究。详细介绍了导致“频谱泄露”现象的原因,并阐述了改善频谱泄露和信号失真的方法--50%重叠加窗法、反加窗法。频域的干扰抑制模块可分为干扰检测和干扰消除两部分。因此,本文同时详细介绍了用于自适应计算干扰门限的N-Sigma算法,研究了用于限幅的条件中值滤波器并对其进行了改进。最后对相关算法组成的频域窄带干扰抑制方案进行了仿真比较。(4)根据仿真结果,用Verilog从时域和频域上实现了窄带干扰抑制模块。验证模块功能后,将模块加入导航信号的接收系统。然后对加入窄带干扰模块前后的系统进行测试,给出了测试结果。
[Abstract]:Global Navigation Satellite System (GNSS), through all-weather and continuous broadcasting of navigation signals, enables real-time location, navigation and supervision of targets. GNSS has been used in many fields, such as production and life. But in a complex wireless environment, through long distance transmission, the satellite navigation signal is very weak when it reaches the ground. At the same time, the navigation signal is also disturbed by a variety of intentional and unintentional, which makes the receiver unable to work properly. Narrowband interference is a common kind of interference. Therefore, the narrowband interference suppression module should be added to the receiver so as to ensure the normal operation of the receiver. Under the premise of single antenna receiving navigation signals, this paper mainly studies the narrow-band interference suppression technology in the time domain and frequency domain. On this basis, we implemented the 50% time overlapped window filter and LMS filter in the frequency domain. According to the different characteristics of the navigation signal and narrowband interference in time domain and in frequency domain, this paper mainly do the following work: (1) through the analysis of the interference type face of the receiver, a model of the navigation signal and narrowband interference received, and according to the model of narrowband interference receiving machine is analyzed in detail. (2) based on the thought of prediction and estimation, the narrowband interference suppression technique of navigation signals is studied in the time domain. The basic principles of LMS (Least Mean Square) and its improved variable step size filter, LS (Least Squares) and LSL (Least Squares lattice) filter are introduced in detail, and the narrow-band interference suppression performance of each filter is simulated and compared. (3) the basic principle of frequency domain narrowband interference suppression is introduced, and the related algorithms involving modules are studied in depth. The cause of the phenomenon of "spectrum leakage" is introduced in detail, and the method of improving the spectrum leakage and signal distortion, --50% overlapping window method and back window method, is expounded. The interference suppression module in frequency domain can be divided into two parts: interference detection and interference cancellation. Therefore, this paper introduces the N-Sigma algorithm for adaptive computation of interference threshold, and studies the conditional median filter used for clipping, and improves it. Finally, the frequency domain narrowband interference suppression scheme, which is composed of the related algorithms, is simulated and compared. (4) according to the simulation results, the narrowband interference suppression module is realized in the time domain and frequency domain by Verilog. After the function of the module is verified, the module is added to the receiving system of the navigation signal. Then the system is tested before and after the narrow band interference module is added, and the test results are given.
【学位授予单位】：电子科技大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN967.1

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