The CMU SensorWeb system comprises of 2 primary components, The node and the base. The node is capable of having 5 analog, 5 digital, 2 differentail, and 1 pulse sensor attached. Some of these sensors include moisture, EC, PAR, temperature, RH, leaf wettness, wind speed, wind direction, and rain fall. The base gets data from the many nodes that can be deployed and passes the data on to a computer where users can interact with the nodes using the user interface.
The user interface provides a password protected site that allows for centralized control of the network. From this interface users can modify node settings, irrigation control settings, and monitor the all the sensors connected to the nodes.
The user interface gives the user the ability to define "Virtual Sensors" these are important values that are computed based on various sensor values. Some examples of virtual sensors are Vapor Presure Deficit (VPD) and dew point. The interface has an easy to use plotting tool that lets the user plot any sensor as well as the virtual sensors that are defined.
Each node has 2 relays capable of controlling a 240VAC load with up to 2A. The default controler uses setpoint irrigation using this diagram.
The nodes are compatible with several radios. This allows us to work with both 900MHz and 2.4GHz frequencies based on the consumers needs. This also lets us be compatible and log data from Decagon nodes.