Galieo系统频率和信号设计现状

介绍了Galileo系统频率和信号设计方案。对Galileo系统选用的信号频段、各频段的中心频率、码率等主要参数、Galileo系统服务与信号的对应关系进行了研究。并对Galileo系统和GPS系统的兼容性和协同工作性进行了比较分析。     

Galileo系统的频率和信号结构

根据近期公布的由Galileo信号任务组制订的Galileo频率和信号结构计划，列出了Galileo选用的频率和信号结构，包括数据周期，伪随机噪声码扩频的实施等，它考虑了和GPS系统的全兼容和相互共用问题，但对码序列选择、导航电文格式内容等方面尚未确定，有待今后进一步研究确定后公布。     

Galileo系统指标和导航信号结构

介绍了Galileo系统的工作指标、载波频率、信号体制和导航数据格式；并与GPS、GLONASS系统进行了比对研究，对于设计我国自主卫星导航系统具有参考价值。     

Galileo系统指标和导航信号结构

介绍了Galileo系统的工作指标、载波频率、信号体制和导航数据格式;并与GPS、GLONASS系统进行了比对研究,对于设计我国自主卫星导航系统具有参考价值.     

Galileo系统接收机测距性能分析

Galileo系统是欧盟提出并正在研制建设的全球卫星导航定位系统，本文从用户使用角度出发，简要论述了Galileo系统频率计划和信号体制设计情况，详细分析了不同频点、不同信号体制下Galileo系统接收机测距性能。     

一种非组合Galileo三频精密单点定位方法及精度分析

同时播发多个频段的导航信号已经成为新一代GNSS卫星的显著特征与未来趋势。多频导航信号设计对提升GNSS精密单点定位精度及缩短初始化时间方面尤其具有重大意义。本文提出了一种利用非组合Galileo三频观测数据的PPP定位算法,采用实测Galileo三频数据按照该算法进行了解算,并采用传统双频算法对相同数据进行解算形成参照,结果显示Galileo三频PPP算法在定位精度及收敛速度上均优于传统双频PPP算法,这种优势在观测数据异常时更为显著。     

Galileo系统特性简析

本文描述了Galileo系统的组成和信号结构，并将其与当前已投入使用的GPS和GLONASS系统进行了比较。文中的各项数据来源均来自Galileo办公室正式发布的文件，翔实可靠，可以作为设计Galileo用户终端的参考。     

发射信号不完善性对卫星导航系统内及系统间干扰的影响分析

研究了3种典型的卫星发射信号不完善性——载波泄漏、互调失真和杂散辐射对于卫星导航信号的接收所带来的干扰,通过信号建模以及谱分离系数、码跟踪谱灵敏度系数和等效载噪比的解析计算对干扰效果进行量化分析;针对GPS和Galileo系统L1/E1频段的信号进行了多层次的仿真计算,给出了综合考虑噪声、信号损耗、外源干扰、GNSS系统内和系统间干扰,以及3种信号不完善性单独作用、两两组合和综合作用下的结果,其中对于GPS L1C/A短码考虑了电文调制对线谱的影响。结果表明,当总的不完善干扰功率水平达到一定程度后,其对接收机信号捕获跟踪和解调的影响大于系统间干扰,不能忽略。     

Galileo电离层折射误差高阶项的四频改正方法

研究了电离层对Galileo观测信号的主要影响及电离层折射误差模型。针对Galileo中的四个频率,系统推导了四个频率的电离层改正模型及相位观测值无电离层组合(LC组合)模型。该模型将电离层折射误差模型改正至三阶项,可进一步提高Galileo定位精度,同时,为Galileo定位提供了有力的技术手段。     

GPS/Galileo/BDS系统测距信号精度分析与评价

随着Galileo、BDS的建设和GPS的发展完善,多系统多频融合的趋势促进了多模GNSS接收机产业化应用。利用零基线双差法对GPS/Galileo/BDS双频观测值进行测距信号精度评估,通过24h的观测数据分析,结果表明Galileo IOV卫星双频观测值残差值最小,测距信号精度最优,其次是BDS;Galileo与BDS系统载波相位观测精度均优于2mm,伪距观测精度优于0.2m,GPS系统测距信号精度相对较差。同时,通过对比Trimble NET R9、Septentrio POLARX4及Javad TRE_G3TH_8三种不同类型接收机间观测值残差及基线坐标偏差,得出NET R9和POLARX4接收机内部噪声水平相当,TRE_G3TH_8稍差的结论。     

BDS-3新频率与Galileo单频组合伪距单点定位精度分析

为对比分析北斗三号（BDS-3）/Galileo相同频率伪距单点定位精度,基于MGEX（Multi-GNSS Experiment）分布的跟踪站实测数据,分析了BDS-3、Galileo以及BDS-3/Galileo单系统单频、双系统相同频率组合和非相同频率组合伪距单点定位精度. 经研究发现,BDS-3/Galileo相比单系统有效提升了卫星可见数与卫星空间分布几何结构,在单系统定位方面,BDS-3系统B1C和B2a伪距单点定位精度优于Galileo对应相同频率的伪距单点定位精度,在双系统定位方面,BDS-3/Galileo相同频率组合伪距单点定位精度优于非相同频率组合,双系统组合定位对Galileo单系统定位精度提升优于BDS-3,表明BDS-3相同频率的设计有效地提升了与Galileo系统的兼容性.      

Identifying a low-frequency oscillation in Galileo IOV pseudorange rates

Galileo, the European global navigation satellite system, is in its in-orbit validation phase and the four satellites which have been available for some months now have allowed a preliminary analysis of the system performance. Previous studies have showed that Galileo will be able to provide pseudorange measurements more accurate than those provided by GPS. However, a similar improvement was not found for pseudorange rate observations in the velocity domain. This fact stimulated additional analysis of the velocity domain, and, in particular, an unintended oscillatory component was identified as the main error source in the velocity solution. The magnitude of such oscillation is less than 10 cm/s, and its period is in the order of few minutes. A methodology was developed to identify oscillatory components in the Galileo IOV pseudorange rate observables, and it was verified that the measurements from Galileo IOV PFM and Galileo IOV FM2 are affected by a small oscillatory disturbance. This disturbance stems from the architecture adopted for combining the frequency references provided by the two active clocks present in the Galileo satellites. The issue has been solved in Galileo IOV FM3 and Galileo IOV FM4, and the oscillatory component has been eliminated. We also propose a methodology for removing this unwanted component from the final velocity solution and for determining the performance that Galileo will be able to achieve. The analysis shows that Galileo velocity solution will provide a root-mean-square error of about 8 cm/s even in the limited geometry conditions achieved using only four satellites. This shows the potential of Galileo also in the determination of user velocity.     

GNSS制导的野外火扑救弹的Galileo引导系统

介绍了一种野外火扑救弹的Galileo引导系统，它是以首选独立的Galileo双频多通道接收设备作为扑救弹载体的单一制导源。该制导系统能够为扑救弹提供高精度实时的三维PVT参数和载体姿态的测量，并且具有与GPS／GLONASS的兼容、独立和协同性特点，从而能够连续可靠地制导野外火扑救弹以快速、准确、高效和安全地对森林大火进行有效的阻隔与扑救。     

GPS、Galileo及其组合系统导航定位的DOP值分析

利用Galileo系统的轨道参数模拟了Galileo系统的卫星位置，并计算出DOP值，比较了同一地点同时段内GPS和Galileo的能见卫星个数及DOP值。与单个系统相比，GPS／Galileo组合在任意地点、任意时刻的观测卫星个数增加．其DOP值明显变小；同时计算了组合系统在不同卫星高度角情况下的DOP值变化，发现在卫星高度角较高时仍可以接收到四颗以上的卫星．其DOP值也能达到导航定位的要求。     

利用单频GPS／Galileo组合观测值的导航性能分析

针对不同观测值的初始方差比值,对比GPS／Galileo组合单点定位的结果。利用不同测站的观测数据和广播星历数据进行单频GPS／Galileo组合单点定位试验。结果表明,组合GPS／Galileo单点定位的平面方向精度优于2m,高程方向精度优于4m,点位精度优于5m;相比于GPS单系统,GPS／Galileo组合系统在平面方向的定位精度略有提高,高程方向的定位精度改善率为11％。同时给出基于4颗IOV卫星的Galileo单点定位结果。     

BDS-3多频点伪距单点定位性能研究

针对目前有关北斗三号系统伪距单点定位研究较少，未对三号系统多个频点的定位性能进行对比分析的现状，本文利用实测数据对三号系统多个频点的定位性能进行了研究，并联合BDS-2、Galileo进行了同频伪距单点定位试验，统计分析了组合定位多个频点的同频定位结果。试验结果表明：目前三号系统单独定位能力有限，不适合单独定位；BDS-3/Galileo同频组合定位可以弥补BDS-3新频点单频定位时卫星个数不足、数据不完整导致的定位精度过差的情况，同时能够提高Galileo的定位精度；BDS-2/3的B3I频点与BDS/Galileo组合的B2b频点的定位精度均与GPS的L1频点的定位精度相当。     

伽利略系统信号调制体制研究

伽利略卫星导航系统的第一颗实验卫星已经发射到太空。在信号调制方面，除使用二元偏置载波（BOC）调制技术外，还首次使用了交替二元偏置载波（ALTBOC）调制技术。总结了伽利略卫星导航系统各信号的信号调制方式、各频段的信号调制体制，特别是BOC调制及ALTBOC调制技术的基本原理。然后，通过对伽利略卫星导航系统调制参数变动过程的研究，分析了在频谱及调制体制方面伽利略卫星导航系统与GPS的兼容性。     

Galileo civil signal modulations

Spectrum limitations for navigation systems require that the various navigation signals broadcast by the Galileo system must be combined and must utilize bandwidth-efficient modulations. At the L1 band, one of the most important questions is how to combine all the Open Service signals and the Public Regulated Service signal at the payload level, while maintaining good performance at reception. The Interplex modulation, a particular phase-shifted-keyed/phase modulation (PSK/PM), was chosen to transmit these signals because it is a constant-envelope modulation, thereby allowing the use of saturated power amplifiers with limited signal distortion. The Interplex modulation was also taken as baseline at the E6 band to transmit the three channels and the services associated on the same carrier frequency. At the E5 band, the modulation must combine two different services on a same constant envelope composite signal, while keeping the simplicity of a BOC implementation. The constant envelope Alternate Binary Offset Carrier (ALTBOC) modulation was chosen as the solution to transmit the Galileo E5 band signal. The main objective of this paper is to study these Galileo modulations. After the introduction, the E5 band signals are described, followed by the Alternate BOC modulation which has been chosen to transmit them. The second part describes the general formulation of the Interplex modulation and its key parameters for an optimal multiplexing of the Galileo L1 band signals. Since the Galileo Open Service signals at the L1 band are still not yet completely specified, different test cases are considered and their impact on the resulting choice for the Interplex modulation parameters is exposed.     

Estimation and analysis of Galileo differential code biases

When sensing the Earth’s ionosphere using dual-frequency pseudorange observations of global navigation satellite systems (GNSS), the satellite and receiver differential code biases (DCBs) account for one of the main sources of error. For the Galileo system, limited knowledge is available about the determination and characteristic analysis of the satellite and receiver DCBs. To better understand the characteristics of satellite and receiver DCBs of Galileo, the IGGDCB (IGG, Institute of Geodesy and Geophysics, Wuhan, China) method is extended to estimate the satellite and receiver DCBs of Galileo, with the combined use of GPS and Galileo observations. The experimental data were collected from the Multi-GNSS Experiment network, covering the period of 2013–2015. The stability of both Galileo satellite and receiver DCBs over a time period of 36 months was thereby analyzed for the current state of the Galileo system. Good agreement of Galileo satellite DCBs is found between the IGGDCB-based DCB estimates and those from the German Aerospace Center (DLR), at the level of 0.22 ns. Moreover, high-level stability of the Galileo satellite DCB estimates is obtained over the selected time span (less than 0.25 ns in terms of standard deviation) by both IGGDCB and DLR algorithms. The Galileo receiver DCB estimates are also relatively stable for the case in which the receiver hardware device stays unchanged. It can also be concluded that the receiver DCB estimates are rather sensitive to the change of the firmware version and that the receiver antenna type has no great impact on receiver DCBs.