Wireless sensor networks are used in a wide range of fields. Besides health monitoring systems, building automation and millitary applications, environmental monitoring is also an important area of wireless sensor networks. The new product of Evopro Kft, the wireless network of rail-temperature measurement (eRTM) gives a solution for scanning and forecasting all problems which are caused by the temperature change of rails. The task of my thesis is to design a handheld diagnostic instrument which can support the installation of the sensor nodes with field measurements.
The first step in the design was to get to know the characteristics of the wireless sensor networks. I studied the architecture of these networks with the help of OSI reference model. The lower layers are specified by IEEE 802.15.4 standard and the upper layers by ZigBee protocol, which is based on 802.15.4 standard. I got familiar with Digi XBee radio modules and with Digi proprietary alternative protocol, DigiMesh. I examined closely the radio module of XBee 868LP, which is used in eRTM sensor networks. After the acquisition of theoretical knowledge I developed the method for supporting installation of sensor nodes and then I set up the precise requirements of the instrument. I defined the block diagram based on these requirements and then I selected the components needed for my task. I prepared the schematic and the PCB design with Altium Designer. I began the design of the firmware with choosing the right software architecture. I continued the developement giving the software system plan and writing the components of the given system. At the end of my thesis I provided the technical specification of the instrument and the evaluation of the design.