Mining Contract: Advanced Software Radio Techniques for Improved Range and Reliability of Digital Through-the-Earth Communication Systems
This work develops an Advanced Software Radio (ASR) for through-the-earth (TTE) communication, providing an improvement in noise immunity over current digital radio performance, with the intent of significantly improving reliability of TTE links in the working areas of coal mines and extending range.
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, Vital Alert will apply different modulation and coding techniques that have been identified to combat man-made electrical noise. The company has already developed three different commercial off-the-shelf (COTS) digital TTE radio system products, including commercially available systems for hard rock mining and tunneling applications, and an intrinsically safe system (approval pending) for coal mine emergency communications. These products are all based on a proven digital TTE radio platform that is built using custom digital signal processor (DSP) hardware. The radio functionality, including conventional band-pass and comb filters, is implemented in firmware already running on the DSP processor. The proposed new modulation or coding techniques can be implemented by upgrading the DSP processor (using evaluation boards) and modifying the radio firmware. Based on proven COTS products, this approach avoids the need to develop new hardware, reduces project risk, and provides a clear path to commercialization.