Mining Contract: Radio System Modifications for Improved Mine Safety (Medium Frequency)

Contract Status & Impact

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

Communication after an incident in a mine is a critical component of miner evacuation and rescue. One way that trapped miners or miners in remote areas can communicate with the surface or with rescue personnel is by using a magnetic induction, medium frequency (MF) radio communication system. OMSHR had previously funded the development of mine MF radios whose signals may couple onto any conductors within a mine entry, such as ungrounded continuous water pipes, power lines (energized or de-energized), trailing cables, and phone wires. However, these conductors are not present in mine bleeders and other remote workings. Testing shows that it might be possible to propagate MF signals in bleeders using just a metal-core lifeline or similar conductor, and then interface the MF communications with the mine’s existing primary communication system. Such a system might allow communication from remote workings to the surface of the mine.

Kutta Radios, Inc., was contracted to enhance functionality to MF radios by (1) increasing radio system performance and situational awareness on the surface; (2) building a signal strength device to measure MF signal; (3) building an MF coupler that would allow for better coupling to a transmission line for longer distances underground; and (4) building a device to allow the MF radios to run off line power and also use alkaline batteries, which can last for prolonged periods of time. Another original objective of this contract was to determine how MF technology could be used to provide low-cost communications solutions for small mines, which was achieved through another OMSHR contract with Kutta Radios: “Communication and Hazard Monitoring in Bleeders and Remote Workings.”

As a result of this contract research, Kutta successfully designed and built an inductive clamp coupler for use with MF conductive cables, produced a software program that controls the functionality of a DRUM 100 MF radio over a serial link, and demonstrated the operation of the improved features at OMSHR’s Safety Research Coal Mine (SRCM) in Bruceton, PA. As of 2014, an enhanced small MF radio is being used in the bleeders of a Pennsylvania mine, allowing for real-time voice communication in remote areas of the mine.