The communication systems used in undergound mining generally consist of the following:
The telelphone has become an integral part of mine communication and is mainly used to locate and inform key personnel. The telephones used in underground coal mines are intrisically safe due to the hazardous mine atmosphere.
Radio wave transmissions in undergound mines encounter problems because of interference from roadway supports and losses occuring from other aspects of mining. This has been overcome by the use of the leaky feeder system. This system allows a regulated amount of radio frequency to “leak” into the raodway from a cable running the length of the roadway. This enables radio transmission to be made from the entire length of the roadway.
Local communications systems are generally used only along the longwall face. These are an intercom style system where the message is relayed to every point along the face and also the stage loading facilities. The use of amplifiers and loadspeakers allows the system to be heard over the noise of the longwall machinery. The intercom systems are not located at every longwall supports but are installed at regular intervals along the face.