Research On Backend Test System Of Optical Fiber Frequency Transmission

With the widespread popularity of 5G and the mushroom growth of the Internet of Everything,time-frequency synchronization technology plays an increasingly important role in the coordinated work of devices and even the orderly operation of the whole society.In addition to its application in production and life,high-precision time-frequency synchronization technology has also made great achievements in scientific research fields such as astronomical observation,physical constant measurement,aerospace observe and control,etc.Affected by factors such as solar rays,electromagnetic storms,and near-Earth multipath effects,the traditional time-frequency synchronization system based on satellite can not keep up with the increasing precision demand for high-precision time and frequency signals in the fields of production and scientific research in terms of accuracy and reliability.Because of the characteristics of small attenuation and high reliability,optical fiber has become a new medium of time-frequency transmission system.The time-frequency transmission system based on optical fiber has developed rapidly.The time-frequency transmission system of optical fiber consists of two parts:frequency transmission system and time transmission system.For the frequency transmission system based on optical fiber,there are mainly three test methods:double mixing time difference method,quadrature phase detection method and phase shift fixed amplitude method.The double mixing time difference method uses the Allan variance analyzer,that has high precise measure.However,it needs complicated equipment and operations,and its measurement range is limited.The other two methods have low requirements for the equipment,simple operation and wide measurement range.But as a result of the lack of corresponding components specially developed for these two methods,the overall measurement accuracy is low.Therefore,developing a high-precision,highly-integrated backend test system for the optical fiber frequency transmission system that combines the quadrature phase detection method and the phase shift fixed amplitude method,which provides a low-cost,easy-to-operate and accurate method for the frequency transmission system is extremely significant.This dissertation develops an effective backend test system for optical fiber frequency transmission system and conducts a detailed performance evaluation for the test system.The specific work includes:1.Analysis of the overall scheme of the backend test system of the optical fiber frequency transmission system.In this dissertation,three measurement methods of stability are studied.In consideration of the different characteristics of the measurement methods,the overall design scheme combining the quadrature phase detection method and the phase shift fixed amplitude method is determined.According to the actual situation of the transmission system and the relevant requirements of stability measurement,the overall performance indicators of the backend test system are determined.2.Design and realization of the circuit of the backend test system of the optical fiber frequency transmission system.According to the overall performance indicators,this dissertation allocates various performance indexes to different parts of the system and performs chip selection.Based on the selected module chips,design and optimize the circuit of each functional module,realize the integration of the system,so as to complete the test system.3.Relevant tests of the backend test system.According to the current instruments in the laboratory and the specific conditions of the optical fiber frequency transmission system,this dissertation designs a complete measurement scheme and conducts relevant tests for each module of the back-end test system and the system as a whole.The test shows that the system can well evaluate the function of our optical fiber frequency transmission system.The specific performance indicators are:the stability of the first part of the back-end test system is 1.3×10-16/s and 2.5×10-19/10000 s;the stability of the second part is 2.1×10-16/s and 1.4×10-19/10000 s.To sum up,this dissertation develops a reliable backend test system for the current optical fiber frequency transmission system.Through relevant tests,the system demonstrates satisfactory performance and can provide high-precision performance evaluation for the optical fiber frequency transmission system.This is of great significance for promoting the development of optical fiber frequency transmission systems.