The Design And Implementation Of Multi Device Clock Synchronization System

With the planning and construction of the integrated measurement and control information system,the scientific research and test task needs to be carried out under the premise of highly unified time information among several equipments in the test site area.At present,the time synchronization among most devices is carried out through the traditional network communication mode,but considering the security and confidentiality of the test task.All the test equipment in the test site must be highly isolated from the Internet.It is very important to realize clock synchronization in the isolated system.In order to solve this problem.It is necessary to design and develop a special clock synchronization system according to the working principle and application characteristics of NTP Protocol Network Time Protocol.The computer can synchronize its server or clock source(such as time center,Beidou satellite GPS,etc.)to provide high precision time correction.Encryption validation can also be used to prevent malicious protocol attacks.On the basis of deeply studying the working principle and basic algorithm of NTP protocol,the network time delay,the supply of client time source and the correction and maintenance of local clock in C / S model are studied.A new clock synchronization algorithm for network delay measurement is designed by using data packet selection method.The system is composed of hardware and software with emphasis on the reasonable sharing of software and hardware functions.The application software architecture is hierarchical.Modular design,by Wireshark comprehensive analysis,real-time traffic capture and statistics.The software is composed of four independent processes,such as real-time push and application traffic analysis.Open source code such as Wireshark Winpcap is used in the development of the software.The common module is multiplexed by the process in different ways.By connecting multiple computers and multiple time servers,the clock synchronization between multiple computers and multiple time servers is realized.Using Visual studio6.0 for interface development,based on the form of dialog box to interact with the user,clock information and timing results are displayed in the dialog box.Users of the dialog box can configure the connected server.The main research results of this paper are as follows:1.Through the combination of software and hardware,the software design is optimized,the system can synchronize the clock between many devices,the system has good performance of collecting,the ability of application layer protocol analysis and extension is strong,and the realization cost is low.It is suitable for application in the measurement and control system of scientific research and test task.2.Using NTP network time protocol,millisecond precision can be obtained.This technology can provide high precision time correction,and can use encryption verification to prevent malicious protocol attack.It has broad application prospect.3.According to the characteristics of the network and combined with various network time synchronization algorithms,the active algorithm based on the C / S communication mode is selected as the basic structure of the algorithm.This model is flexible and simple,and can make a relatively good judgment on network delay.It is based on the existing synchronization algorithm and the classical network time protocol(NTP).A set of time synchronization algorithm which adjusts the client clock to synchronize with the time server by the combination of frequency modulation and phase modulation is constructed,and the recognition speed is fast.This method fills the gap in the software of clock synchronization tool for XXX unit measurement and control system.4.the clock information obtained by the application system can provide a credible reference for data acquisition and performance evaluation between test and control equipment in the test field.The results of test and application show that the system can meet the needs of the synchronization of the clock in the measurement and control system and play an important role in the research and test task.