卫星导航接收机中窄带干扰抑制技术的研究与实现

发布时间：2018-08-12 18:32

【摘要】：全球卫星导航系统能够提供精确定位、测速和授时等服务,具有实时、连续和全天候等特点,不仅广泛应用于铁路、公路、航运和通信等公共服务行业,而且应用于航空航天、巡航导弹、单兵装备和水面作战舰艇等军事领域,它是个国家经济安全和的国防安全重要保证。由于导航卫星信号的调制频率和调制特性都是公开的,而且导航卫星信号的功率到达地球表面最弱时只有-160dBw,非常容易受到各种各样的信号干扰,例如来自人为的压制式干扰,还有来自环境中各种潜在的电磁信号的干扰等。在今天信息化时代的背景下,电子对抗已经成为战争的重要部分,能否在高复杂的电磁环境中提供有效的导航,成为一场战争胜负的关键。因此,研究卫星导航接收机中干扰信号的抑制技术具有重要的意义。论文首先综述了国内外时域窄带干扰抑制技术和变换域窄带干扰抑制技术的发展状况,分析和对比了GPS、GLONASS、GALILEO和BeiDou等全球主要的卫星导航系统,给出了潜在干扰和人为干扰等常见的干扰信号类型；然后,在分析卫星导航接收机基本组成原理的基础上,对GPS信号和C/A码的生成过程进行了详细描述,给出了利用到达时间测距和利用伪随机噪声码定位的卫星导航接收机原理；根据卫星导航接收机窄带干扰抑制的原理,分析了窗函数的应用,推导出了加窗造成的信号信噪比损耗表达式；其次,基于窗函数选择的原理,给出了反加窗和重叠组合算法,提出了使用重叠选择和反加窗算法相组合的窄带干扰抑制方法,并阐述了基于固定门限值和自适应门限值的窄带干扰抑制门限选择的方法,研究了硬件实现中信号截位的误差和改善信号截位误差的Dither方法；最后,利用VHDL语言实现了FPGA硬件环境下的窄带干扰抑制功能,阐述了开发工具、VHDL硬件描述语言和Xilinx FPGA处理器件等实现窄带干扰抑制功能的软硬件开发环境,给出了窄带干扰抑制模块的实现流程,详细地分析了FFT与IFFT计算模块、加窗与反加窗模块、ROM存储器模块和重叠选择模块的实现方法和设计流程,描述了自动增益控制模块的功能、实体结构和实现流程等,利用Modlesim和ChipScope测试平台,对不同条件下窄带干扰抑制模块进行了性能和功能测试,并基于信号截位原理,对信号截位进行了测试。
[Abstract]:Global satellite navigation systems can provide accurate positioning, speed measurement and timing services, with real-time, continuous and all-weather features. They are widely used not only in public services such as railways, highways, shipping and communications, but also in aerospace, Cruise missiles, individual military equipment and surface warships are important guarantees of national economic security and national defense security. Because the modulation frequency and modulation characteristics of the navigation satellite signal are open, and the power of the navigation satellite signal reaches the earth's surface only -160 dBw, it is very vulnerable to various kinds of signal interference, such as artificial suppression interference. There is also interference from various potential electromagnetic signals in the environment. In the background of today's information age, electronic countermeasure has become an important part of the war. Whether to provide effective navigation in the highly complex electromagnetic environment is the key to the success or failure of a war. Therefore, it is of great significance to study the suppression technology of interference signal in satellite navigation receiver. Firstly, this paper summarizes the development of narrowband interference suppression in time domain and narrow band interference suppression in transform domain, and analyzes and compares the main satellite navigation systems such as GPS / GLONASS / GALILEO and BeiDou. The common types of jamming signals such as potential interference and artificial interference are given, and then the generation process of GPS signal and C / A code is described in detail on the basis of analyzing the basic principle of satellite navigation receiver. The principle of satellite navigation receiver based on time of arrival ranging and pseudorandom noise code positioning is presented, and the application of window function is analyzed according to the principle of narrowband interference suppression of satellite navigation receiver. The signal-to-noise ratio (SNR) loss expression caused by windowing is derived. Secondly, based on the principle of window function selection, an inverse windowing and overlapping combination algorithm is presented, and a narrowband interference suppression method combining overlapping selection and inverse windowing is proposed. The selection method of narrowband interference suppression threshold based on fixed threshold value and adaptive threshold value is expounded, and the signal intercept error and the Dither method to improve the signal intercept error in hardware implementation are studied. The narrowband interference suppression function in FPGA hardware environment is realized by using VHDL language. The hardware and software development environment of FPGA hardware description language and Xilinx FPGA processing device are described. The realization flow of narrowband interference suppression module is given, and the implementation method and design flow of FFT and IFFT computing module, window adding module and inverse window adding module, ROM memory module and overlap selection module are analyzed in detail. This paper describes the function, entity structure and implementation flow of the automatic gain control module. The performance and function of the narrowband interference suppression module under different conditions are tested by using Modlesim and ChipScope test platform, and based on the principle of signal truncation. The signal intercept is tested.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN965.5

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