光纤分配网多点高精度时频传递方法研究

Fiber-based time and frequency distribution network providing high-precision synchronization services of time and frequency for multiusers in local areas.It is the crux for the terrestrial time and frequency network to realize the wide distribution and popular application of the standard time and frequency signals, which lays a solid foundation for many fields, such as navigation and positioning, exploration of deep space, synergy of command and control, synchronization of the communication network and scientific researches. Considering the typical topology, transfer span, and demand for the network transfer of the standard time and frequency signal, the project is to study the methods of self-sensing and self-compensating the degradations of the transferred time and frequency signals at client side, guaranteeing the transferring performance and reducing the network complexity. Methods of monitoring and assessing the performance of the clients in real time are to be researched to improve the usability of the dissemination network. Also the restrictions among the network resource, the transferring performance and the user capability are to be researched to explore the limitation and optimization of the distribution network. Moreover, the project is to develop techniques for the joint transfer of time, frequency and communication signals by a shared channel, improving the service integrity of the network and the utilization of the channels. Experimental network is to be established to verify and optimize the proposed methods for point-to-multipoint time and frequency transfer as well as the methods for client-side performance assessment. The research results of the project could provide theoretical and technical support for the further study and application of the terrestrial time and frequency transfer network in future.

光纤时间频率分配网在区域范围内为多个用户提供高精度时间频率同步服务，是陆基时频网络实现时频基准信号高精度广泛传递、充分发挥效能的关键，在导航定位、深空探测、指控协同、通信网同步和科学研究等领域具有重要的基础支撑作用。项目针对光纤分配网典型拓扑结构、网络跨距和标准时频信号的网络化传递要求，研究时频信号传递误差终端自感知和自补偿方法，在保证时频传递性能的同时降低网络复杂度；提出时频网络终端性能实时评估方法，研究评估效能，提升时频分配网络的可用性；研究时频分配网络资源、传递性能与用户容量之间的制约规律，探索网络性能容量极限和优化方法；研究时间、频率、信息三类信号共享信道混合传递方法，提高时频网络服务完整性和信道利用效率；搭建光纤时频分配实验网络，验证优化多点高精度时频传递方法和性能评估效能；本项目的研究将为陆基时间频率分配网后续研究应用提供理论方法和技术支撑。

项目研究中针对时频信号高精度、网络化传递的需求，在光网络多点时频传递自感知、自补偿和自评估方法，时间、频率和信息混合传递、网络容量与性能理论极限和空间激光授时信道的动态时延特性四个方面进行了研究。.项目提出了树型和环型网络拓扑条件下，时频终端站误差自感知、自补偿的方法，搭建了200km的光网络时频传递实验平台。在树型拓扑网络中采用往返传输的无源补偿法，在环型网络中采用环路时延广播加终端补偿法，实现了授时误差小于50ps，频率万秒稳定度损失小于5.0E-17的时频传递性能。针对现有光纤通信网络为单纤单向链路的现状，提出了双纤单向传输的光纤授时自感知和自评估方法，实验研究了该方案的可行性。.为解决利用单载波实现时间、频率和信息同时传递的实际需求，提出了时频混插法和副载波调制法并实验研究验证了所提方法的有效性。在传送频率较低的时频网络中，将秒脉冲和信息插入到频率信号的低电平空隙处，在终端站利用数字处理技术分离低速的秒脉冲、信息和频率信号；而在传送射频信号的时频网络中，利用副载波调制技术将时间信息先经负载波调制到一个与待传频标不同的中频上，然后已调中频信号与频标信号耦合后同时调制一个激光器，在时频终端利用精细滤波技术分离两类信号，从而实现了时、频、信混合传递。.项目建立了光强度噪声、色散、色散温变效应、Sagnac效应，光纤温度变化和光电频率串扰等因素对时频传递性能的影响模型，分析了时频传递网络所能达到的性能极限。探究了噪声和色散温变影响下，环型光纤网络和树形光网络的网络容量与时频传递性能之间的量化关系。基于大气分层模型研究了空间激光授时中大气折射率变化导致的双波长授时偏差，仿真和实验研究了湍流导致的授时时延的随机抖动。.在项目支持下，在国内外正式出版期刊发表学术论文17篇，其中SCI检索文章7篇，EI检索文章9篇，申请国家发明专利3项，培养硕士研究生4名，博士研究生2名。