Mining Contract: Through-the-Earth Communication Systems for Underground Coal Mines: Product Final Development and Standardized Interface Definition

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Contract # 200-2011-39884
Start Date 9/1/2011
End Date 11/30/2012
Research Concept

This contract will extend the operational range of a through-the-earth (TTE) communications system while maintaining the portability and permissibility of the subsurface unit.

Topic Area

Contract Status & Impact

This contract is complete. To receive a copy of the final report, send a request to

As part of a previous contract, E-Spectrum Technologies developed a prototype, proof-of-concept TTE communications system that leveraged technologies previously developed for the oil and gas industries. TTE systems require an antenna to be located underground with a complementary antenna located on the surface. This technology demonstrated the ability to increase the horizontal distance between the underground TTE system antenna and the location of the rescue operation antenna on the surface. This technology advancement provides the mine operators with greater flexibility when selecting the location for the surface antenna.

To serve the specialized communications challenges of the mining industry, greater range is needed in TTE technology; TTE systems are typically reliable up to around 1,000 feet and in some cases up to 2,000 feet. To meet this challenge, E-Spectrum Technologies was again contracted to increase the range of this TTE technology to 3,000 feet (horizontal plus vertical) and beyond using metal-cased boreholes or some alternative to boost the range. Also, E-Spectrum Technologies was tasked to redesign the existing system to limit the electrical current required for the underground transceiver to reach a permissible level necessary for use in coal mines.

Under this contract, a new TTE system called the Rescue Dog was designed and constructed. This text-only TTE technology has been tested at two underground mines, successfully operating over a total approximate surface to underground distance of 1,590 feet and 2,060 feet. Test mines allowing the full 3,000 feet goal were not available, but signal strength recorded by the Rescue Dog suggests the system could successfully achieve this goal. The technology developed under this contract was applied to the system currently approved by MSHA for permissibility.

Page last reviewed: July 18, 2016
Page last updated: October 6, 2014