Research On High-precision Time Identification Technology In Laser Bidirectional Time-Frequency Transmission

With the development of navigation technology and time-frequency reference,satellites need more accurate time reference and higher frequency stability for navigation.This puts forward higher requirements for the stability of time-frequency transmission,and it is difficult to improve the microwave frequency synchronization method commonly used in modern technology.The time-frequency transmission stability in optical fibers is usually several orders of magnitude higher than that of microwaves,which means that the time-frequency transmission method with light as a carrier has great potential.The application of optical-borne laser time-frequency transmission technology to the space optical path The research focus of this topic.The laser time-frequency transmission used in this paper uses the IEEE1588 time synchronization protocol for time synchronization,useing digital double-mixing time difference measurement technology,to detect the phase difference of the clock recovery signal after communication is received,and the frequency difference is integrated into the algorithm of the precise time synchronization protocol to perform the frequency synchronization.The advantages of this architecture are obvious,the phase information of the double-ended clock is extracted by means of mixing,which solves the situation of single-clock ambiguity in simple time synchronization protocols.The research content of this paper mainly includes two parts.The first is to analyze the requirements related to the time-frequency transmission of space lasers,and to explain what hardware components and index considerations are needed to implement time-frequency transmission technology in laser links.The second is the research on the key technology of time-frequency synchronization in laser time-frequency transmission,high-precision time-frequency transmission requires high-precision phase subdivision ability.In this paper,the time synchronization method and phase measurement are combined to design high-precision Time-frequency transfer mode.The structure of this article is as follows:First,the background,physical objectives and structure of the experiment are introduced.Then,the requirements of laser time-frequency transmission and the link architecture are analyzed,and the current laser time-frequency transmission target is pointed out.Then,the energy margin calculation of the link is designed for the laser time-frequency transmission system,and the laser time-frequency transmission is designed.The structure of the system's optical transceiver;finally,the method to solve the problem of clock synchronization in long-distance asynchronous communication is theoretically introduced.The next part starts from the requirements of laser time-frequency transmission,and introduces two key technologies used in time-frequency transmission: IEEE1588 timesynchronization protocol and DDMTD digital dual-mixing time difference measurement technology.Then,the two key technologies are described in detail,and the two key technologies are combined to design a time-frequency transfer scheme for joint measurement of time synchronization and phase discrimination.By analyzing the noise that may occur in various locations in the system,the sources of noise in the system during normal use are enumerated.Finally,tested the performance of the time-frequency transmission system.The composition of the experimental system and the test equipment are introduced first,and the schematic diagram of the composition of the fiber-space test system is given.Tested the performance of space laser time-frequency transmission system,after analyzing the data,the time synchronization stability accuracy of the master and slave in the system is 90ps(3?).