Mining Contract: Leaky Feeder to Wireless Media Converter Device Technology Development

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Contract # 200-2008-26815
Start Date 8/14/2008
End Date 7/30/2009
Research Concept

This contract will develop and test a Media Converter Device (MCD) that allows 802.11b wireless handheld radios to communicate with leaky feeder communication systems. This will significantly improve voice quality and underground communications coverage in cross-cuts and drifts, which currently have little to no communications due to signal propagation limitations of leaky feeder technology. This effort will involve the integration of commercial over-the-counter (COTS) hardware, packaging, testing and Mine Safety and Health Administration permissibility design considerations.

Topic Area

Contract Status & Impact

This contract is complete.

To receive a copy of the PowerPoint presentation from the final program meeting, send a request to In addition, Rajant's MCD Interim Progress Report (including a Field Trip Summary Report) is also available by request to 

By December 2008, Rajant personnel designed, built, and lab tested a prototype Media Control Device (MCD) that allows most handheld radios to work with existing leaky feeder systems in underground mines.

Rajant then evaluated two competing hardware platform choices (BridgeCom and C4i) for technical viability, size, weight, ease of use, and performance. Rajant conducted a host of tests in-house and chose the C4i platform with integrated computing capability as the interoperability device for the MCD. C4i has a number of Radio Interface Unit (RIU) products for connecting handheld radios to an IP network. The RIU is a small, 4-port device which can be delivered as a gateway or with an integrated media server. The RIU has serial ports enabling remote control of frequency, mode, and other radio functions, and each RIU can be provided with desktop and server software to form a complete communication solution.

In March 2009, Rajant submitted its latest status report and proposed MCD in-mine test plan, as well as the Very Low Frequency (VLF) Through-the-Earth (TTE) Interface Feasibility Report (a deliverable).

Rajant packaged the RIU, BreadCrumb, radio, and power interface unit and tested it at Arch's Mountain Laurel longwall mine near Sharples, WV, on April 15, 2009. It also utilized a secondary MCD (using a borrowed RIU from C4i) to support additional test scenarios in the mine. A field trip report submitted on April 29 indicated that all tests were successful and proved that the MCD technology developed under this program was able to provide the required capability and service in an operational scenario.

Rajant tested the MCD in NIOSH's Safety Research Coal Mine on July 22 and demonstrated it to NIOSH personnel on July 30. Rajant gave a final PowerPoint presentation and delivered the final prototype Media Converter Device to NIOSH on July 30, 2010.

Page last reviewed: July 19, 2016
Page last updated: July 19, 2016