GPS接收机多径抑制算法研究

发布时间：2019-04-28 15:31

【摘要】：随着全球定位系统（GPS）的普遍应用，干扰抑制成为了研究热点。信号的干扰因素有很多，尤其是在具有许多高楼大厦、桥梁等建筑物的城市环境中，存在不同程度的多径误差。多径误差是GPS系统测量中最主要误差来源之一，其不能像电离层误差和对流层误差等误差源一样，可以通过差分技术或建模来消除，因此抑制多径误差成为现在全球卫星导航系统的热点和难题。本文的主要工作如下：在概述GPS系统基本组成和GPS信号的结构与特点的基础上，重点介绍了GPS接收机跟踪环的基本工作原理，并利用卡尔曼滤波器仿真实现了载波跟踪环中的环路滤波器。在分析了GPS系统中测量误差主要来源和特点的基础上，，重点研究多径误差的来源和特点；基于多径信号的一般数学模型，重点研究了多径信号对GPS跟踪环的影响。通过分析对比了窄相关技术、Strobe相关器技术和ELS（Early Late Slope）多径抑制技术等经典的基于鉴别器函数的多径抑制算法，针对这些算法的性能受接收机前端预相关带宽以及噪声的影响，提出了一种基于随机Hough变换（RHT，Randomized HoughTransform）估计相关峰两边斜率的多径抑制算法，并通过仿真分析对比了ELS多径抑制技术和基于RHT的斜率估计多径抑制算法的性能。通过对基于最大似然估计的多径延迟锁定环的仿真分析，针对MEDLL（MultipathEstimating Delay Lock Loop）算法性能受到噪声和相关器个数的影响，提出一种基于Kalman滤波改进的MEDLL算法，并通过仿真对比分析了该算法与MEDLL算法的性能。基于扩展卡尔曼滤波（EKF，即Extended Kalman Filter）的基本原理，设计并仿真了基于EKF的GPS跟踪环，利用动态估计得到输入信号各参数，达到抑制多径的目的。
[Abstract]:With the widespread application of global positioning system (GPS), interference suppression has become a research hotspot. There are many interference factors, especially in the urban environment with many high-rise buildings, bridges and other buildings, there are multi-path errors in varying degrees. Multipath error is one of the most important sources of error in GPS measurement. It can not be eliminated by difference technique or modeling like ionospheric error and tropospheric error. Therefore, the suppression of multipath error has become a hot and difficult problem in the global satellite navigation system. The main work of this paper is as follows: on the basis of summarizing the basic composition of the GPS system and the structure and characteristics of the GPS signal, the basic working principle of the GPS receiver tracking loop is introduced emphatically. The loop filter in carrier tracking loop is simulated by Kalman filter. Based on the analysis of the main sources and characteristics of the measurement errors in the GPS system, the source and characteristics of the multipath errors are studied, and based on the general mathematical model of the multipath signals, the influence of the multipath signals on the GPS tracking loop is studied emphatically. The classical multipath suppression algorithms based on discriminator function, such as narrow correlation technique, Strobe correlator technology and ELS (Early Late Slope) multipath suppression technique, are analyzed and compared. For the performance of these algorithms is affected by the pre-correlation bandwidth and noise of the receiver front end, a multipath suppression algorithm based on random Hough transform (RHT,Randomized HoughTransform) to estimate the slopes of the correlation peaks is proposed. The performance of the ELS multipath suppression technique and the slope estimation multipath suppression algorithm based on RHT are compared by simulation. Based on the simulation analysis of multipath delay locking loop based on maximum likelihood estimation (MLE), an improved MEDLL algorithm based on Kalman filter is proposed to improve the performance of MEDLL (MultipathEstimating Delay Lock Loop) algorithm due to the influence of noise and correlator number. The performance of this algorithm is compared with that of MEDLL algorithm by simulation. Based on the basic principle of EKF, (Extended Kalman Filter), the GPS tracking loop based on EKF is designed and simulated. The parameters of the input signal are obtained by dynamic estimation, and the multipath suppression is achieved.
【学位授予单位】：华东交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：P228.4

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