Recent development testing of the Two-Way PED system at BHPB's West Cliff Colliery in NSW, Australia confirmed two-way through-the-earth text messaging at a depth of 480 metres (1,575 feet).
As reported earlier this year MST and CSIRO have reached an agreement to bring the previous research on two-way, through-the-earth signalling to a commercially available product.
With previous testing at mines between 90 m (300 ft) to 290 m (1,000 ft) it was encouraging to be able to transmit two-way text messages between the surface station and the underground station through this 480 m depth of cover.
Text messages were transmitted between the surface and underground directly through the rock strata in 5 to 10 seconds. The quality of signal reception at this depth confirms that all coal mines in Australia, and the majority of coal mines in United States, would be able to implement such a system wanted to. In fact the signal levels at 480 m indicated coverage should be achievable to approximately 600 m (2,000 ft).
Though the technology has been proven as operable, there is still considerable industrial design to be undertaken to have the initial stage 1 repeater stations to be available as an intrinsically safe product.
The initial application for the repeater stations would be at Refuge Bays, Breathing Apparatus Change over Stations, etc underground. This would allow messages to be sent directly through the overlying rock strata to the surface from these locations. Mine site Technologies remain confident these repeater stations will be available by mid-2008.
Mine site Technologies are appreciative of BHPB allowing them to undertake the tests and the assistance given by West Cliff personnel in undertaking the tests.