Last month, a Q-Track team traveled to the historic Safety Research Coal Mine in Bruceton, Pennsylvania to conduct RF propagation and performance tests on a Near-Field Electromagnetic Ranging (NFER®) Real-Time Location System (RTLS). We optimized the system for use in a mine environment in an effort funded by NIOSH. We deployed three receivers spaced 150-200 feet along a single passage and demonstrated accurate tracking in a 400ft x 100ft (40,000 sqft) area of the mine. The low frequency (575kHz) signals bend and diffract around corners, enabling accurate tracking in a parallel passageway substantially beyond line-of-sight of the three receivers in the primary passageway. This ability to obtain accurate tracking in non-line-of-sight environments is a hallmark of NFER® RTLS. Here’s a brief (82 second) clip showing the performance.