Design and Implementation of a Time Source Selecting and Monitoring System for the Telephone Speaking Clock

Abstract : As an added-on system of the Time Synchronized Speaking Clock (TSSC), the time source selecting and monitoring system (TSMS) together with its design and implementation are major concerns in this paper. The service offered by the TSSC is generally called the "117" time service and the telephone number "117" seems to be a symbol of the national standard time in Taiwan, since it is used frequently by the public to calibrate their time machines. Due to its popularity in daily uses, it is very important to keep the system running smoothly and providing reliable time service. The paper describes how to construct TSMS, including two sub-systems. One is for multi-time signal source selection and the other for data monitoring and recording, which would strengthen reliability of the TSSC. Considering continuity of future development in TSMS, we chose UML (Unified Modeling Language) to express abstract concepts of the system behaviors and to generate its blueprint. Finally, TSMS has been successfully implemented according to this blueprint. At the present time, the system is in operation and actual monitoring data are collected and analyzed. Charts of round-trip delays and fluctuations of synchronized time signals could also be plotted. According to these results, we see that the system has indeed brought evident benefits to enhance reliability of the TSSC system.