北斗卫星系统中伪码捕获技术的研究

发布时间：2018-04-23 02:32

本文选题：北斗接收机 + 信号捕获　；参考：《安徽大学》2016年硕士论文

【摘要】：北斗卫星导航系统(BeiDou Navigation Satellite System, BDS)是我国独立研发的卫星导航系统,它的成功研制将在全球范围内为我国提供卫星定位导航服务；同时它也是当前世界上较为先进的卫星导航系统,已经在生产、生活、科学研究、国防建设等众多领域中得到了广泛的应用。接收机系统对伪码(Pseudo-random noise code)信号的捕获是实现卫星导航定位功能的关键,而伪码捕获速度的快慢直接反应了接收机性能的优劣,所以本文将对北斗卫星系统中伪码快速捕获技术进行深入的研究。论文在研究对比几种常见的伪码捕获算法的基础上,对相关算法改进后得到一种适用于北斗二代卫星信号接收机基带信号快速捕获算法。论文主要从以下几个方面进行了论述：首先介绍了全球卫星导航系统的发展历程,借此引申出我国北斗卫星导航系统；接着阐述了北斗卫星导航系统的发展历史,说明了自主研发全球卫星导航系统的重要意义,进而提出对北斗卫星接收机系统中伪码信号捕获技术的研究。然后论文介绍了北斗卫星导航系统的理论基础,在介绍完北斗卫星系统的组成结构之后,着重分析了北斗卫星信号的构成；从北斗信号的载波、伪随机噪声码和调制方式等方面详细分析了北斗信号的特性。介绍完北斗卫星系统之后,进一步分析北斗接收机中信号捕获的原理,以及对信号的多普勒频移、数据码的长度、频率搜索步长和捕获门限值等信号捕获过程中所涉及的重要参数分析。论文第四部分介绍并分析了三种常用的信号捕获算法,分别是匹配滤波器法、串行时域捕获算法和并行码相位捕获算法。了解了它们的优缺点之后,分析提出了一种基于部分匹配滤波器与FFT结合捕获算法,该算法利用了FFT的性质把传统算法中对信号伪随机噪声码相位和载波频率的二维搜索过程变成了只对伪随机噪声码相位搜索的一维过程,这样极大的缩短了信号捕获所需要的时间；信号载波的搜索是通过FFT估算出的多普勒频移调节接收机本地复现信号,从而实现信号载波的快速捕获。然而对具有较长周期的伪随机码信号进行捕获时,这种部分匹配滤波器与FFT结合的方法将会消耗更多硬件资源。因此对部分匹配滤波器结构进一步改进,采用能够实现长周期伪码快速捕获且硬件资源消耗小改进方法,即用折叠匹配滤波器的结构代替部分匹配滤波器实现长伪码信号快速捕获,这样改进后的折叠匹配滤波器与FFT结合算法不仅能实现伪码信号的快速捕获,还能极大的减小硬件资源的消耗。最后分析折叠匹配滤波器的原理与结构,并对北斗二代伪码信号进行仿真验证,证明该算法的有效性。
[Abstract]:BeiDou Navigation Satellite system (BDSs) is a independently developed satellite navigation system in China. Its successful development will provide China with satellite positioning and navigation services on a global scale. At the same time, it is also a relatively advanced satellite navigation system in the world at present. Has been widely used in production, life, scientific research, national defense construction and many other fields. The acquisition of pseudo-random noise code signals by receiver system is the key to realize satellite navigation and positioning, and the speed of pseudo-code acquisition directly reflects the performance of the receiver. In this paper, the pseudo-code fast acquisition technology in Beidou Satellite system will be deeply studied. Based on the research and comparison of several common pseudo-code acquisition algorithms, a fast base-band signal acquisition algorithm for the second generation Beidou satellite signal receiver is obtained by improving the correlation algorithm. This paper mainly discusses the following aspects: firstly, the development course of global satellite navigation system is introduced, by which the Beidou satellite navigation system of our country is extended, and then the history of the development of Beidou satellite navigation system is expounded. The significance of independently developing global satellite navigation system is explained, and the research of pseudo-code signal acquisition technology in Beidou satellite receiver system is put forward. Then the paper introduces the basic theory of Beidou satellite navigation system. After introducing the structure of Beidou satellite system, the paper analyzes the structure of Beidou satellite signal, the carrier wave of Beidou signal, and the structure of Beidou satellite navigation system. The characteristics of Beidou signal are analyzed in detail from pseudorandom noise code and modulation mode. After the Beidou satellite system is introduced, the principle of signal acquisition in the Beidou receiver, the Doppler frequency shift of the signal and the length of the data code are further analyzed. The analysis of the important parameters involved in the signal acquisition process, such as the frequency search step size and the acquisition threshold value. In the fourth part of the paper, three common signal acquisition algorithms are introduced and analyzed, which are matched filter method, serial time domain acquisition algorithm and parallel code phase acquisition algorithm. After understanding their merits and demerits, a novel acquisition algorithm based on partial matched filter and FFT is proposed. The algorithm utilizes the properties of FFT to transform the two-dimensional search process of the phase and carrier frequency of the signal pseudorandom noise code into a one-dimensional process which only searches the phase of the pseudorandom noise code. In this way, the time needed for signal acquisition is greatly shortened. The search of signal carrier is to adjust the local reproduction signal of the receiver by Doppler frequency shift estimated by FFT, so as to realize the fast acquisition of signal carrier. However, when the pseudorandom code signal with long period is captured, the combination of the partial matched filter and FFT will consume more hardware resources. Therefore, the structure of partial matched filter is further improved, and the method of fast acquisition of long period pseudo code and small improvement of hardware resource consumption is adopted. The structure of folding matched filter is used instead of partial matching filter to realize fast acquisition of long pseudo code signal, so the improved folding matching filter combined with FFT algorithm can not only realize the fast acquisition of pseudo code signal. Can also greatly reduce the consumption of hardware resources. Finally, the principle and structure of folding matched filter are analyzed, and the simulation results of Beidou second generation pseudo code signal show that the algorithm is effective.
【学位授予单位】：安徽大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TN967.1

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