Research And Development Of Embedded And Precision Network Time Server Based On Network Time Protocol

With the rapid development of computer networks, time using the internet is more and more demanded. Present the most widely used is NTP Network Time Protocol, IPC as a network time server and GPS as a source of accurate time, however, IPC has high cost, size large and the phenomenon of death and other shortcomings, widespread used is not easy; GPS is an important part of global strategy of the United States, if we can not get GPS timing service, NTP server can not obtain an accurate time source and can not provide users with accurate time. In this theis, we propose an embedded high-precision NTP network timing solutions.To ensure high-precision performance of NTP servers, we designed a timekeeping program based on ABC. Even if the time sever could not get GPS services, but can maintain accurate timekeeping function; Embedded system as a NTP time service not only can effectively solve the problem of the phenomenon of death and high cost, but also can improve the accuracy of NTP server.For this design, completed the overall design of the system and selection of appropriate hardware. CPLD was used to implement ABC logic circuit; TDC was used to implement high-precision time interval measurement; LM3S8962 Microcontroller was used to develop NTP timing unit, the controller has an integrated Ethernet controller, easy to develop and implement network communication protocols.Finally, we tested the entire design, The initial frequency accuracy of OCXO(rated frequency is 20MHz) better than±2×10^-9, aging rate of±0. 15×10^-9per day, after GPS calibrated, timekeeping deviation of the local unit can be as low as 1.2ns/s,using Delphi development tools to Develop the NTP client application, respectively broadcast mode and client /server model has been tested.