Low power sensor platform for environmental monitoring

A novel sensor buoy platform was developed for detailed environmental monitoring of coastal areas. Using many buoys in a mesh network on low power ZigBee basis allows dramatic reduction of the overall power consumption, enabling an autonomous operation on a single battery set over 3 y. Each buoy acts as sensor node but also as router forwarding messages from neighbor buoys to a centralized server. Thus special attention had to be directed to network synchronization and the handling of processor sleep states. One-wire temperature sensors were used for temperate profiling. Moreover the platform is equipped with several analog and digital inputs allowing the connection of additional sensor and sensor systems. The fist buoy network was designed based on 2.5 GHz RF modules (Atmels ATmega1281 together with the AVR Z-Link AT86RF230). According the specifications of the manufacturer under perfect conditions the maximum transmission range is about 4 km. A maximum buoy to buoy distance of approximately 400 m could be achieved. Instead of 2.5 GHz technology the final version of the buoys was then equipped with 868 MHz transceivers. A buoy to buoy distance of 3 km was possible.