Research And Implement Of Networked Timing System Based On Ethernet

Timing System is an integated system composed of some electrical equipments, which implemented the unification of time and frequency of the whole system by provide the standard time and frequency signal. With the development of scientific technology such as navigation,communication,power and etc, Timing System is needed by more and more engineer and scientical domain. The application of Timing System is extensive in the national defence, economic, foundation research. The traditional Timing System implemented the unification of time and frequency by transmiting B-code through coaxial-cable, the synchronous presicion can reach the millisecond.With the development of the network technology including Ethernet, the time synchronous technology has the great advanced. Especially using IEEE1588 standard, the time synchronous precision of Ethernet reaches nanosecond grade, obtain and exceed the traditional timing system precision based on B-code technology. With the progress of the Network, Networked Timing system as the renovation of the traditional timing system has the great advantage. The Networked Timing system which this paper discussed is the one based on Ethernet using the IEEE1588 standard. The following four aspects of the networked timing system based on Ethernet is studyed and implemented in the paper.1. The paper discussed the topology of the Networked Timing system based on Ethernet. The PTP clock module is designed as the clock timing and frequency calibration part, the phase-shift and frequency-divide clock as the timekeeping part, two parts make the clock model. Then functional analysis is made for the master and slave clock of the Networked Timing system.2. The software and hardware design of PTP clock model is study and implement. The hardware platform, PTP DEMO, is designed for the IEEE1588 clock model with DP83640 hardware assisted. The software design is to implement the PTP message transmission based on UDP/IPv4 protocols and IEEE1588-2002 time synchronous arithmetic after hardware platform is ready.3. The PTP timescale is implemented based on UTC(NTSC) time, and the key transform flows is explained in detail, the platform of master clock and GPS receiver module is set up, the transformation of PTP to UTC(NTSC) is implemented in the master clock and the slave one.4. The time synchronization and system construction of the Networked Timing system is study and implement. Firstly, the software arithmetic framework of the master clock is dissertated using the RTX which is a real-time operation system, and the seven tasks of the master clock arithmetic is study in detail. Secondly, the software arithmetic framework of the slave clock is dissertated, and the time synchronous arithmetic is achieved. Subsequently, the study is made to setup the multicast network, including the multicast virtue analysis, the multicast network implement, the research about collision and the slave clock numbers.Finally, the test platform of the master and slave clock is setup, the time synchronous precision is analyzed. Firstly, the synchronous Ethernet mode is introduced, and the synchronous precision of the master clock and the slave one is reached to sub-nanoseconds. Secondly, the different frequency signals as the PTP clock frequency sources is used by the slave clock and the influence of time synchronous precision is made. Subsequently the different threshold is selected to analyze the time synchronous precision influence of the master clock and the slave one. Finally, the master clock and slave one are linked by the hub or switch, the time synchronous precision is researched.