Mining Project: Communications and Tracking Systems Modeling and Performance

Research Summary

This project had four research aims, as follows:

1. Determine the performance characteristics of existing radio frequency identification tracking devices.
2. Develop experimentally validated electromagnetic computational models that determine the signal path-loss for low radio frequency propagation in which the electromagnetic waves can propagate directly through the earth, linking a miner underground to personnel on the surface.
3. Develop experimentally validated electromagnetic computational models that determine the signal path-loss for radio frequency propagation at very-high, ultra-high, and super-high frequencies in an underground coal mine.
4. Develop experimentally validated electromagnetic computational models that determine the signal path-loss for radio frequency propagation at medium frequencies through parasitic coupling within an underground coal mine.

The MINER Act of 2006 mandated that mine operators adopt two-way wireless underground communications and electronic tracking (CT) systems that allow personnel on the surface to communicate with and determine the location of workers underground. As a result of this legislation, wireless CT systems in mines should provide a vital link between the surface personnel and trapped miners to assist them in self-escape or rescue.

This project developed and validated computer models to predict CT radio signal propagation in the frequency bands known to work in underground coal mines. Coal mine CT systems operate in one of three frequency bands: typical radio communications frequencies in the UHF (ultra-high frequency) band (or possibly the adjacent bands just below or above UHF); the MF (medium frequency) band; and the ULF (ultra-low frequency) band. The mechanism of RF wave propagation and attenuation is different in each of these bands.

Through these research efforts, this project resulted in a better understanding of CT system performance limitations in an underground environment and provided guidelines to improve the effectiveness and performance of critical mine systems. The findings can also extend and/or enhance the communication range of underground CT systems during post-accident scenarios.