The Design And Application Of Distributed NTP Precise Timing Server Based On ARM&GNSS

As the development of modern information system, network system, especially distributed system is widely used in various industries and fields increasingly. Some critical applications are based on time synchronization. Conventionally, the time synchronization is reached by regulating the physical clock of the equipment precisely with precision clock, or is realized by the related time protocol inside the LAN. Due to various limitations, the distributed precise time synchronization is an issue. However, the demands for precision of distributed time and accuracy of time synchronization are higher. The research of new distributed network time synchronization is a critical problem to be solved, which has not only engineering value, but also certain theoretical meaning.Firstly, beginning with the application of the distributed system, this paper described the theory and technology, such as GNSS satellite time service, NTP protocol, embedded system and uClinux operating system. The necessity and engineering meaning of solving the problems of precise timing and synchronization in the distributed system are discussed, and the features of GNSS time service and the mechanism of NTP network protocol are analyzed.Secondly, based on the high demand for real-time of network synchronization, a design architecture of GNSS-based embedded NTP timing server is put forward, and the function, structure and principal of the main modules are analyzed for functions and performance. The 32-bit ARM S3C44B0X is used as the microprocessor of the hardware control core, and the application circuit mainboard with multiport is developed, with GNSS satellite communication module.For software, the details of the bottom interface of uClinux operating system are analyzed deeply. The uClinux embedded operating system and its driver is migrated to the designed server hardware platform. The NTP application is designed and integrated with the modular concept, to realize the compiling of NTP protocol and NTP time service. Of which, the main parameters and the detail working process of the NTP protocol are analyzed and set systematically.Finally, by capturing the precise unified system clock and based on the time service provided by NTP protocol, combining the specific application in the commanding system for weather modification, the application integration of precisely synchronous emission of rocket projectile by command for the distributed rainmaking rocket projectile emission points is realized. Proven by the preliminary test, the timing server designed in this paper works well, as well as meets the high demand for precise synchronization of distributed applications from the different levels.