Time Synchronization Method Based On Wireless Sensor Network And It's Application

The campus,regardless of primary school,middle school or college,cannot work without a bell,because a bell must be used in a ‘legal' classroom as the beginning and end of the time base which is center of the campus activities,which can promise the reliability,accuracy and consistency of the daily teaching process.During a college entrance examination,English grade examination,computer grade examination and the title foreign language test and other national activities,bell reset must be needed.However,improving reliability and convenience of the management of current campus clock is still a complicated point where we need to conquer.This paper analyzes status and technical characteristics of several campus clock synchronization and publishing technologies,especially the role and the significance of the campus clock,and the technology that can be used for clock synchronization and publishing.The principle and key problems of Zigbee time synchronization technology are discussed,and the feasibility scheme of campus clock synchronization based on multi-hop Zigbee wireless network is discussed.The clock source of release system based on WSN has variety of ways,including GPS,BDS,Internet,etc.By comparison,BDSis more suitable for campus clock system.On the basis of previous research,a new campus clock system based on ZigBee protocol is proposed in this paper,consisting of one main the campus clock system and several teaching building nodes arranged as a star-type network.The whole system includes one main server node and several teaching building nodes,being a star type network in physical.Multi-hot technologymay be used with high accuracy.The main server can use ordinary computer,using the RS232 C serial interface to connect the BDS interface module and obtain the clock reference.Then use the RS485 serial port to connect Zigbee wireless sensor network module,publishing clock information through the wireless sensor network to the various teaching building nodes,so every lower node can calibrate local date and timein the end.In addition,the main server can periodically publish ringing timetables,and even publish different ringing timetables to some specific teaching buildings to meet the special needs.During a national unified examination,an updated schedule will be released through the main server instantly.In order to improve the reliability,the node will give a feedback signal which will be disposed by the main server later when a controller or bell failed.In addition,with a little expansion,the system can also be used publishing notice of fire alarm,power outage,bad weather and other emergency news.This paper completed the campus clock release and bell synchronization system,including the system hardware and the whole working procedures.The high reliabilitycampus clock release and bell synchronization system,including the system hardware and the whole working procedures,is suggested in this paper.The experiment proves that the scheme is feasible.