Research On Railway Time Synchronization Technology Based On IEEE1588

Railway time synchronization network is an important part of railway communication network,which provides unified standard time information for each system of railway,so as to ensure the accurate fault location and train operation safety.At present,the railway time synchronization network mainly uses the Network Time Protocol(NTP)for time synchronization between railway systems.With the improvement of train operation speed,the requirement of the system for synchronization accuracy is gradually increasing,and the problem of insufficient time synchronization accuracy of the NTP has become increasingly apparent.Therefore,it is the general trend to find a more accurate time synchronization protocol to replace the current NTP.According to the structure and communication mode of railway time synchronization network,this thesis studies the implementation of the railway time synchronization network using the IEEE1588v2 protocol for time synchronization.Based on the application status analysis and research of the railway time synchronization network communication process,it is considered that the current network time protocol synchronization accuracy is insufficient and needs to be improved.In-depth study of the IEEE1588v2,the feasibility of replacing the NTP with the IEEE1588v2 is concluded,and the railway time synchronization network has the conditions for using the IEEE1588v2 protocol.This thesis designs the hardware and software of the railway time synchronization module.Hardware system design Based on the AM3358 of ARM Cortex-A8 core as the core processor of the clock synchronization module basis,it integrates a network PHY chip to achieve IEEE1588v2 time synchronization without external hardware,thus simplifying the circuit design of the baseboard.The design of the software system is based on a pure software PTPd2 implementation.At the same time,the clock servo system and the optimal master clock algorithm are researched,and five kinds of message processing flows are designed.The asymmetric link is analyzed and a correction scheme is designed.The time offset compensation method based on a three-layer BP neural network is used tocorrect the asymmetric link,thereby improving the synchronization accuracy of asymmetric link.Finally,the experimental platform is set up and the time synchronization accuracy of the three synchronization schemes is tested.The experimental results show that the synchronization accuracy of the three design schemes is higher than current railway time synchronization network,which can meet the synchronization accuracy requirements in most application scenarios of the railway time synchronization network.