GPS信号仿真与实测数据离线分析

发布时间：2018-06-23 13:59

本文选题：GPS + 信号体制　；参考：《中国科学院研究生院（国家授时中心）》2013年硕士论文

【摘要】：随着全球卫星导航系统（Global Navigation Satellite System,GNSS）应用的日益广泛，全世界主要大国纷纷建设自己的卫星导航系统，，形成GPS、GLONASS、Galileo和北斗既竞争又互补的局面。想要在如此多的卫星导航系统中屹立于不败之地，导航信号质量的优劣是重要的指标之一。导航信号质量的优劣，直接关系到卫星导航系统的性能，同时也反映了卫星有效载荷的工作状态和各种电性能指标。信号质量评估可以为卫星导航系统的信号设计及关键技术在轨试验验证提供手段及支撑。因此，导航信号评估工作引起了国际上该领域的高度重视，在GPS、欧洲Galileo和北斗等导航系统的建设过程中，都建设了配套的导航信号监测与分析评估平台。本文的研究工作主要从两部分展开：首先对GPS信号体制进行分析，对GPS信号中采用的各种调制方式，包括GPS现代化中采用的新型TMBOC调制技术，从功率谱和自相关函数两个方面进行了分析与仿真；然后针对两种不同类型的实测数据——基带信号与监测接收机数据进行了质量评估，给出了不同数据的质量评估指标，并且利用实测数据进行了算法验证，以图表的形式给出了实测数据的评估结果。基于基带信号的数据评估，主要是从时域、频域、调制特性和相关特性等几个方面展开。其中时域特性主要是分析信号的时域波形图、眼图；在频域主要是分析信号的功率谱密度（PSD），本文主要采用的是Welch周期图法来进行PSD的研究与带宽的估计；调制特性重点分析了基带信号的星座图以及相位误差；相关特性的分析主要是从相关峰展开的。基于监测接收机的数据评估，主要是从稳定性、一致性、多径效应三个方面展开。信号的稳定性主要是从伪距和载波相位的稳定性来判断，本文重点采用最小二乘法通过伪距来分析信号稳定性；一致性又分为码与载波一致性和码间一致性两种，用来衡量卫星信号在调制过程中码与载波的相对抖动情况；本文采用CMC（Code minus carrier）算法推导出了多径效应计算公式，利用该公式对于双频GPS数据的所有采样，载波L1和L2上的多径误差都能够估计。论文最后给出了两种不同类型的实测信号在Matlab环境下评估的具体结果，分析结果进一步证实了论文中采用的信号评估方法的正确性和可行性。这进一步保证了全球导航卫星系统空间信号的连续性与可靠性。
[Abstract]:With the increasing application of Global Navigation Satellite system GNSS (GNSS), major countries around the world have built their own satellite navigation systems, forming a situation of competition and complementarity between GPS GLONASS and Galileo and Beidou. In order to remain invincible in so many satellite navigation systems, the quality of navigation signal is one of the important indicators. The quality of navigation signal is not only related to the performance of satellite navigation system, but also reflects the working state of satellite payload and various electrical performance indexes. The signal quality assessment can provide the means and support for the signal design of the satellite navigation system and the verification of the key technology in orbit test. Therefore, the evaluation of navigation signals has attracted great attention in the world. In the construction of GPS, Galileo and Beidou navigation systems, a complete platform for monitoring and analysis of navigation signals has been built. The research work of this paper is mainly divided into two parts: firstly, the GPS signal system is analyzed, and various modulation methods used in GPS signal, including the new TMBOC modulation technology used in GPS modernization, are analyzed. The power spectrum and autocorrelation function are analyzed and simulated, then the quality evaluation of two different types of measured data-baseband signal and monitoring receiver data are given, and the quality evaluation indexes of different data are given. The algorithm is verified by the measured data, and the evaluation results of the measured data are given in the form of charts. The data evaluation based on baseband signal is mainly carried out in time domain, frequency domain, modulation characteristic and correlation characteristic. The characteristic of time domain is mainly to analyze the time domain waveform and eye diagram of the signal, and the power spectrum density (PSD) of the signal is mainly analyzed in the frequency domain. In this paper, Welch periodic chart method is mainly used to study the PSD and estimate the bandwidth. The modulation characteristics focus on the constellation diagram and the phase error of the baseband signal, and the correlation characteristics are mainly analyzed from the correlation peaks. The data evaluation based on monitoring receiver is mainly carried out from three aspects: stability, consistency and multipath effect. The stability of signal is mainly judged by the stability of pseudo-range and carrier phase. In this paper, the least square method is used to analyze the stability of the signal, and the consistency is divided into two types: code and carrier consistency and inter-symbol consistency. It is used to measure the relative jitter between code and carrier in the modulation process of satellite signal. In this paper, the calculation formula of multipath effect is derived by using the CMC (Code minus carrier) algorithm, which is used to sample all dual-frequency minus carrier) data. Multipath errors on carriers L1 and L2 can be estimated. At the end of the paper, the concrete results of two kinds of measured signals in Matlab environment are given. The analysis results further verify the correctness and feasibility of the signal evaluation methods used in this paper. This further ensures the continuity and reliability of GNSS space signals.
【学位授予单位】：中国科学院研究生院（国家授时中心）
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P228.4

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