Research On Clock Synchronization Technology Of Distributed Test System Based On Wireless Network

With the development of wireless communication technology,distributed test systems based on wireless networks are widely used in test technology.Ensuring clock synchronization between nodes is the basis of the test.The randomness of the wireless network will cause the clock synchronization performance to deteriorate.In response to this problem,this paper uses PTP protocol to develop distributed wireless network clock synchronization technology from four aspects.The factors influencing the clock synchronization accuracy of the wireless network are analyzed.Based on the synchronization principle of the PTP protocol,key technologies such as obtaining time stamps,improving link asymmetry,solving channel competition,and selecting network topology are applied to the wireless network.Design wireless network clock synchronization simulation model,clock noise modeling and synchronization accuracy optimization and wireless network clock synchronization performance experiment to analyze the feasibility of key technologies.Based on the OPNET simulation platform,a PTP wireless network model is constructed by modeling the process domain,node domain and network domain.The clock synchronization accuracy of the PTP protocol in wireless networks,the comparison of the clock synchronization performance of star and tree network topologies,the sequential timing mechanism and the effect of data rate on clock synchronization were simulated and studied.In view of the problem that various uncertain noises in the wireless network affect the clock synchronization accuracy,a mathematical model of clock noise is constructed.The wireless network asymmetry is eliminated by modeling the wireless network PTP clock adjustment method,and the PTP state space model is established and introduced by Karl TheMann filtering algorithm corrects the clock deviation,and simulations verify that the Kalman filtering algorithm can significantly optimize the clock synchronization performance.Put forward the design idea of distributed wireless network test node,select STM32F407 which supports PTP protocol as the main controller,the physical layer chip DP83640 completes the hardware acquisition timestamp,and the WiFi module realizes the wireless interaction of each node data;complete the overall software architecture design and software flow Design and software debugging of wireless communication function;built four different number of test systems for clock synchronization performance test,the results show that:reduce the synchronization cycle,reduce network load and adopt a suitable network topology can increase the clock of wireless network nodes Synchronization accuracy.Finally,suggestions for the principles of wireless network node construction are given.This paper verifies the feasibility and application advantages of the PTP protocol in a wireless distributed test system through the above research,and realizes the high-precision clock synchronization of the wireless network based on the PTP protocol and the accuracy can reach100 microseconds,meeting the basic needs of wireless distributed testing.