Research On Wide Area And High Precision Time Transfer Based On White Rabbit Network

Time and frequency are important strategic resources of the country and the foundation of defense,industry,finance and scientific research.Wide-area and high-precision fiber-optic time transfer is of great significance to the national timing system and time security strategy.At present,high-precision optical fiber time synchronization mainly adopts a point-to-point transmission system,and it is difficult to achieve time synchronization of multiple nodes in a wide area.Improving the coverage of fiber optic time-frequency transmission systems while ensuring high-precision time synchronization is still a problem to be solved.In order to further improve the time synchronization accuracy and extended time synchronization coverage of the fiber synchronous network,this paper focuses on the wide-area and high-precision optical fiber time transfer based on White Rabbit time synchronization technology.The main contents are as follows:(1)Aiming at the influencing factors of high-precision time synchronization of White Rabbit technology,establish a single-fiber bidirectional fiber delay asymmetry and circuit delay calibration method,and analyze the influence of synchronization link delay calibration error on synchronization accuracy.The method can realize the high-precision measurement of the bidirectional delay asymmetry coefficient and the delay of the transceiver circuit in the time synchronization link,and improve the time synchronization accuracy.(2)According to the prominent influence of temperature on the fiber synchronous link,the synchronization performance of the fiber synchronous link under temperature fluctuation is analyzed.A time synchronization method based on temperature compensation and Kalman filtering is proposed.The method uses the experimentally measured optical fiber and transceiver temperature effects as the input control quantity of the synchronous system to correct the one-way delay,and uses the Kalman filter algorithm to filter the noise during the synchronization process.Effectively improve synchronization accuracy and synchronization precision in temperature fluctuation environments.(3)Aiming at the problem of insufficient coverage of high-precision optical fiber time synchronization network,a wide-area expansion method based on OEO and optical amplifier cascaded White Rabbit synchronization link is proposed.The design of White Rabbit synchronous link relay is analyzed.The effects of OEO relay and optical amplifier relay on fiber time transfer are studied.The model of determining relay distance and relay node is established based on the actual White Rabbit synchronization link parameters.The research results in this paper can be applied to the White Rabbit fiber time synchronization network,and provide a theoretical reference for the future construction of terrestrial wide-area fiber optic time synchronization network.Through the compensation filtering method and the relay method proposed in this paper,the time synchronization accuracy and the time transmission distance can be effectively improved.