GPS III首星信号结构及其特性分析

导航信号是连接空间卫星和地面用户端的枢纽，是卫星导航定位系统中最重要的部分之一，其优劣直接影响后续的定位、测速、授时等性能。该文利用国家授时中心40 m高增益天线对GPS III首星进行多次信号采集及比对分析工作，从GPS III L1频点调制矢量及频谱分布入手，对L1频点载波相位存在“滑动”现象进行了深入剖析，得出该现象主要源于L1M信号。利用C/A码解析出授权信号M码，定量分析了L1频点信号分量的S曲线过0点偏差以及功率占比，其中L1M S曲线过0点偏差达到0.058 ns，信号功率占比最高可达6.78。该文研究成果可为研究新一代GPS信号的调制方式提供支撑，也可为后续北斗导航卫星系统信号体制设计以及信号质量评估方法提供参考。

Analysis on Structure and Multiplexing of L1 Signal from Global Positing System III in-orbit Satellites

The navigation signal is the hub connecting space satellites and ground users, and is one of the most important parts of the satellite navigation and positioning system. Its advantages and disadvantages directly affect the subsequent positioning, speed measurement, timing and other performance. The 40 m high-gain antenna of the National Time Service Center is used to conduct multiple signal acquisition and comparison analysis of the Global Positing System III (GPS III) first satellite. Starting from the GPS III L1 frequency point modulation vector and frequency spectrum distribution, an in-depth analysis of the "sliding" phenomenon in the carrier phase of the L1 frequency point is carried out, and it is concluded that the phenomenon is mainly derived from the L1M signal. C/A code is used to analyze the authorized signal M code. The S-curve zero-crossing deviation and the power proportion of the L1 frequency point signal component are quantitatively analyzed. Among them, the L1M S-curve zero-crossing deviation reaches 0.058ns, and the signal power proportion is up to 6.78. The research results of this paper can provide support for the research on the modulation methods of the new generation GPS signals, and also provide references for the subsequent Beidou navigation satellite signal system design and signal quality evaluation methods.