Mining Publication: Performance Evaluation of Electromagnetic Techniques for the Location of Trapped Miners

The Bureau of Mines (NIOSH Mining) has conducted field studies in coal mines throughout the United States to determine the effectiveness of electromagnetic techniques in locating miners trapped underground following a mine accident. Data from these tests have been used to generate models of expected signal and noise distributions as found above mines throughout the coalfields. These distributions have aided in placing the expected performance of a through-the-earth electromagnetic communications technique into a probabilistic framework. Results show that at a 10 percent false alarm rate, the expected probability of detecting a miners signal from a depth of 1,000 ft is 54 percent; at 500 ft it is 95 percent. These depths exceed the actual depths of 90 percent and 50 percent, respectively, of U.S. coal mines. Sensitivity studies have shown that at a depth of 1,000 ft, for every 3 db of improvement in signal-to-noise ratio, the probability of detection increases 6 to 8 percent.