Sensors Anywhere - Sensor Web Enablement in Risk Management Applications

Our system is designed to cope with water depths of around 100m, meaning the number of measurements taken during one dive can be significant. Storage is thus required for the large volumes of measurement data: not only those collected by the diving unit but also from light and acceleration sensors placed on the top of the buoy. System data also needs to be saved; for example, the energy produced by the wave energy generator as well as the available energy. The sheer amount of data exceeds the limited RAM available in sensor nodes. Moreover, to handle the different data types smoothly, we use Contiki's Coffee file system to store data. The data is transferred onshore using GPRS (General Packet Radio Service), and this is too energy-consuming a task to be performed after every dive. We have therefore ported Coffee to operate on SD cards that enable cheap mass storage.