| Summary: | 碩士 === 萬能科技大學 === 工程科技研究所 === 98 === Precise frequency sources play important roles in telecommunications, navigations, power systems, instrumentation and in numerous other applications. Over the years, clocks have become more precise and more accurate. One of the key practical challenges to time technology is the synchronization. The IEEE 1588 standard, i.e., a precision time protocol (PTP), makes it possible to achieve the precise time synchronization over a network. IEEE 1588 addresses the clock synchronization requirements of measurement and control systems. It is a protocol designed to synchronize real-time clocks in the nodes of a distributed system that communicate using a network. The goal of this study is to design a Fuzzy controller for the time servo of PTP to steer the slave clock to synchronize with the master clock. In our system, a Linux-based open source, PTPd, was adopted to implement the IEEE 1588 standard. In the PTPd, the controller of the time servo was originally implemented by PI control. This study established the PTP system using a set of Apple’s Mac mini with preinstalled Mac OS X Lion. Also, the PTPd source code was modified so that it could be run on the Mac OS platform. Experimental results show that within a subnet, for averaging times of about 104 seconds, our system can achieve the time stability of a few sub-microseconds. From the results, although the PI control scheme shows excellent performance in the steady state, it takes a longer time than the Fuzzy control scheme in the transient stage. The proposed system may be applicable to networked distributed systems such as measurement systems, electrical power systems, communication networks, and control systems. There is room for further investigation into developing an optimum controller to reduce the effects on the network delays that will improve the short-term stability of the PTP system. In addition, this study will use the Objective-C to implement the IEEE 1588 standard so that it can be run on the iOS mobile devices such as iPhone and iPad. Thus, the proposed scheme may be applicable to gaming industry, security system, etc.
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