双向比对方法在eLoran系统内应用研究

Research on the application of a two-way comparison method in eLoran systems

  • 摘要: 增强型罗兰(Enhanced Long-Range Navigation, eLoran)系统是国际标准的定位、导航与授时(positioning, navigation and timing, PNT)系统的重要组成部分. 系统采用台链设计,每个台链由1个主台和2~3个副台组成. 为了提供稳定的PNT服务,eLoran台链内各发播台需要实现高精度的时间频率同步. 实现时频同步的方式主要依靠卫星共视、光纤时频传递或者搬运钟等手段,对外部依赖较强. 本文提出了一种eLoran双向时间频率传递技术,利用eLoran系统自身发播的信号,在各个发播台之间实现时间频率同步. 该技术增加系统的独立性,减少对外部系统的依赖. 通过试验验证,该方法在736 km和486 km基线测得钟差数据万秒稳定度均可达10−12量级.

     

    Abstract: eLoran is an important component of the international standard positioning, navigation and timing (PNT) system. High-precision time-frequency synchronization among transmitting stations is essential for stable PNT service, but conventional synchronization methods mainly rely on external techniques such as satellite common-view, optical fiber transfer, or transported clocks. To reduce this external dependence, this paper proposes a two-way time-frequency transfer method based on eLoran signals. In the proposed method, two eLoran transmitting stations receive each other’s signals carrying timing information, perform local time-difference measurements, and exchange observation data to obtain the time-frequency transfer result. Owing to the reciprocal propagation path between the two stations, the propagation delay can be largely canceled. Experimental results on 736 km and 486 km baselines verify the feasibility of the proposed method. The measured 10 000 s stability reaches 10−12, respectively. The results show that the proposed method can realize time-frequency synchronization among eLoran transmitting stations by using the system’s own signals, thereby improving system autonomy and reducing dependence on external synchronization links.

     

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