Research On Stable Radio Frequency Dissemination Over Optical Network

Ultra-stable radio frequency dissemination technology has an outstanding value in communication fields.In recent years,with the increasing accuracy of time and frequency standard such as atomic clocks and optical clocks,traditional time and frequency dissemination schemes are faced with great challenges.As a country with the largest commercial optical network in the world,Chinese researchers are constantly exploring solutions for ultra-stable frequency synchronization over the existed optical network.Frequency dissemination technology based on optical fiber provides a solid foundation for stable frequency dissemination over long distances,and also provides a theoretical guarantee for the further use of commercial optical fiber network for time-frequency synchronization.This paper introduces the development of time-frequency datum and time-frequency dissemination technology,and summarizes the three main technologies of frequency dissemination based on optical fiber,the development processes and the latest research results at home and abroad.The principle of time-frequency dissemination technology based on optical fiber,dissemination model,and the characterization method of frequency stability are summarized.The related factors affecting the stability of frequency dissemination are analyzed.Furthermore,the basic compensation principles of linear dissemination scheme and ring dissemination scheme are compared.Then the application of frequency dissemination technology in frequency synchronization network is analyzed.The traditional frequency dissemination technology shows the defects of poor scalability and compatibility,which couldn't meet the needs of wide range of frequency dissemination.Based on the analysis of the limitation of the traditional compensation scheme in the optical network,we designed a hybrid dissemination scheme over optical network based on optical switch,which provides a new idea for the application of stable radio-frequency dissemination scheme in the optical network.In this paper,we proposed the application of hybrid dissemination scheme over optical network based on optical switch.The dissemination principles of the schemes in linear network topology,tree network topology and ring network topology are introduced respectively.The application prospects of the scheme are analyzed.In order to verify the feasibility and practicability of the compensation principle of the schemes,a VPI simulation was carried out to demonstrate the hybrid dissemination scheme over optical network based on optical switch,and a simulation platform was built to verify the stability of frequency dissemination and the feasibility of the scheme applied in optical network.The simulation results confirmed the fact that the frequency dissemination stability of single station in ring topology can reach 1.26×10-15/s and 8.5×10-18/104s.The frequency dissemination stability of linear single station can reach 2.76×10-15/s and 2.07×10-17/104s.In the ring multi-station dissemination simulation,the three remote stations can obtain the short-term stability of 2×10-15 and long-term stability is more than 10-17.In the dissemination simulation of linear multi-station,the dissemination stability of 4×10-15 and 3×10-17 can be obtained from three remote stations.