A path loss measurement system for mines

RF communications is important in mining, since it can improve operational efficiency and worker safety. Successful RF communications requires an understanding of the RF propagation channel in the mine tunnels. One of the problems with performing channel measurements in a mine is the extreme environment. It generally is not economically reasonable to take expensive test equipment into mines. For example, in potash mines the salt dust in the mine is very corrosive when exposed to higher humidity levels on the surface. This paper describes a low cost path loss measurement system that is designed for the extreme environment in a potash mine. The measurement system uses continuous-wave transceivers with RSSI (received signal strength indicator) outputs. A laptop computer with a 16-bit data acquisition card is used to monitor the RSSI of the receiver. MATLAB, through the Data Acquisition Toolbox, is used to acquire the measurements. These measurements are then converted, using a MATLAB script and previously acquired calibration data, to relative power measurements in dB. This MATLAB based system quickly processes the raw results producing calibrated results that can be viewed and compared at the time of the measurement. This measurement system was used to perform path loss measurements in Cory potash mine near Saskatoon, SK. Some of these channel measurement results are presented.