Synchronized Access to Sensor Networks

Networking distributed sensors over commercial off-the-shelf Ethernet, has on the one hand advantages like simplified integration into existing infrastructure and reduced costs for the network itself, but raises the problem of a consistent global view of the monitored system. A solution is the introduction of synchronized clocks for every sensor node. Consequently, the two tasks of sampling the data at the node and the transmission to a central evaluation system can be disentangled and separated in time. Each node can either be pre-programmed to gather sensor data at certain points of time or configured to attach a timestamp to the acquired data. The paper presents an approach for highly accurate clock synchronization with appropriate hard-and software support, measurement results, and a method for quality management.