Regional and on-farm wireless sensor networks for agricultural systems in Eastern Washington

• Authors: F. J. Pierce;T. V. Elliott
• Venue: Computers and Electronics in Agriculture
• Year: 2008

Recent advances in sensor and wireless radio frequency (RF) technologies and their convergence with the Internet offer vast opportunities for development and application of sensor systems for agriculture. The objective was to create regional and on-farm sensor networks that provide remote, real-time monitoring and/or control of important farming operations that add value through improved efficiency and efficacy of targeted management practices. This paper describes hardware and software components of technologies we developed for regional and on-farm sensor networks and their implementation in two agricultural applications in Washington State, an agricultural weather network and an on-farm frost monitoring network. The regional sensor network consists of our AWN200 data logger equipped with a 900MHz, frequency hopping, spread spectrum (FHSS) radio configured into master-repeater-slave network for broad geographic coverage. A single master is configured with multiple repeaters to provide a RF line-of-sight telemetry backbone network. Independent network backbones from disparate geographic regions are then aggregated in a central database via standard Internet protocols for further processing and dissemination. Software includes firmware to operate the data logger and radio telemetry aspects of the AWN200 in an agricultural weather network application called AgWeatherNet (http://www.weather.wsu.edu). The on-farm sensor network uses our SS100 radio/logger which includes a 900MHz, FHSS radio, with software designed primarily for mobile, real-time farm operations and management applications. The network is deployed in a star topology in which a strategically placed base radio is responsible for network synchronization, data collection from remote stations within the network, and re-broadcasting collected data to roamer radio units attached to mobile computers and/or directly to the Internet. Client software, AgFrostNet, operating on a computer connected to a roamer, collects, manages, and display data in real-time. This software was designed specifically for air temperature monitoring during frost/freeze protection events. Both the regional AgWeatherNet WSN and the on-farm AgFrostNet networks were successfully implemented in Washington State. Problems encountered were mainly associated with power management under periods of low solar energy and with electrostatic discharge (ESD) damage to gallium-arsenide (GaAs) based transmit-receive switches in the radios during storms, a problem now corrected. Both systems have been made commercially available to growers via a novel arrangement between WSU and a local manufacturer.