A Wireless Sensor Network for In-Crop Sensin

This project looks at the operation of wireless sensor nodes in rapeseed using antennas located close to the ground, through both measurements of the propagation loss with test equipment and through building and operating an experimental wireless sensor network. Rapeseed is a technically challenging crop in which to operate a wireless sensor network, due to its dense foliage from ground level up to the canopy. To facilitate these activities two measurement systems have been devised and constructed. One measurement system was designed to allow the measurement of propagation loss in and around the crop. The other was designed to allow the power profile of sensor nodes to be measured. Both of these systems provided information to guide the design of the experimental wireless sensor network. The measurements with the propagation measurement system along with the received signal strength and message loss results from the deployment provide information on the distances over which communication is likely to be feasible with antennas located close to the ground.Sensor nodes and a base station to collect the data from them were designed based on Microchip's PIC18F45J20 microcontroller, MRF24J40 transceiver chip and MiWi software stack with customisations for power management and to record the received signal strength of packets arriving at the base station.Initial propagation loss measurements in a rapeseed crop were made at Rothamsted Experimental Station in 2011. Further propagation loss measurements and a deployment of the sensor nodes in a rapeseed crop were made at Tatton Dale Farm in 2012.