Low-cost leaky feeder communication for mines rescue

Abstract

A low-cost, low-weight leaky feeder system is proposed for mines rescue communication for use when the mine's permanent communication infrastructure has been compromised by an incident. Unlike the leaky feeders that are permanently installed in some transport tunnels and mines, which are very expensive, bulky and heavy, the system described here relies on the fact that some ordinary coaxial cables leak signal unintentionally. Experimental evaluation of the two main types of low-cost coaxial cable identified a suitable cable and an optimal frequency of 27 MHz. Longer range tests characterised the real world underground performance of a system. A range of around a kilometre is achievable but this could be increased substantially by using in-line amplifiers. In comparison to low-frequency guidewire systems that have previously been produced for mines rescue use, the method outlined here does not force rescuers to clip handsets to the cable, thereby allowing them much more freedom of movement.