The locations of nodes are measured by differential GPS receiver or theodolite. And time synchronization among nodes is achieved coarsely via the simple method that the manager node broadcasts the sampling or stop message, and the others execute the corresponding action immediately when receiving the message. 节点位置由差分GPS接收机或经纬仪测量;节点间简单的时钟同步是由管理节点广播采样和停止消息,其他节点收到消息就执行相应的采样和停止动作来完成的。