Mining Contract: Through-the-Earth (TTE) Communications: Range Reliability Improvements
This research will develop and test enhanced magnetics-based communications waveforms with increased ability to provide through-the-earth communication in the presence of ambient noise and interference. Achieving this primary objective will extend the range and coverage of current magnetics-based technologies. Techniques to evaluate the efficacy, range, and coverage for current technologies will be refined and demonstrated.
Contract Status & Impact
This contract is ongoing.
The Mine Improvement and New Emergency Response Act (MINER Act) of 2006 calls for mines to have emergency response plans that “provide for post accident communication between underground and surface personnel via a wireless two-way medium.” Mines have installed systems that are significantly better than what was available in 2006; however, they all depend on infrastructure that to some degree includes copper wire or fiber links and a line of sight between that infrastructure and the worker. Unlike traditional communication methods using higher frequency radio systems, through-the-earth (TTE) radio systems based on very low frequency (VLF) communication using electromagnetic induction allow underground workers to communicate without having “line of sight” or a physically wired or fiber connection, other than the antenna. The use of frequencies in the 0.3 to 9 kHz range allows TTE radio systems to penetrate strata that would typically block traditional radio signals.
TTE radio systems can support voice, text messaging, and data in either duplex or half-duplex (push-to-talk) configurations. The current state of the technology supports voice communication up to a maximum of approximately 1,000 feet and text or data in excess of 1,000 feet. The operational range of TTE radio systems is limited by the external or environmental magnetic noise, which in many instances is man-made, originating from electrical machinery and power lines. This makes it difficult to test the emergency link or use it for operational purposes.
Under this contract, Lockheed Martin is evaluating various waveforms and other techniques that have been identified to combat man-made electrical noise. The company currently has a TTE magnetic-based system approved through the Mine Safety and Health Administration (MSHA) and the new waveforms will be tested using modified versions of that equipment. Based on proven commercial off-the-shelf (COTS) products, this approach avoids the need to develop new hardware, reduces project risk, and provides a clear path to commercialization.
- Mining Communications and Tracking
- Performance Evaluation of Electromagnetic Techniques for the Location of Trapped Miners
- Preliminary Performance Predictions For Electromagnetic Through-The-Earth Mine Communications: A Collection of Working Memoranda
- Propagation of EM Signals in Underground Mines
- Research and Development Contract for Coal Mine Communication System: Volume 3 - Theoretical Data Base
- Theoretical Noise and Propagation Models for Through-the-earth Communication
- Through-the-earth Electromagnetic Trapped Miner Location Systems. A Review
- Through-The-Earth Wireless Real-Time Two-Way Voice Communications
- Two-Way, Through-the-Earth Emergency Communication System for Trapped Miners and the Surface
- Ultra-Low Frequency Through-the-Earth Communication Technology
- Page last reviewed: 10/8/2014
- Page last updated: 10/8/2014
- Content source: National Institute for Occupational Safety and Health, Mining Program