Magnetic Through-the-Earth Miner Transceiver for Emergency Communications

Details

• Personal Author:
  Matthews J
• Description:
  Mining accidents are still a regular occurrence both in the U.S. and worldwide, often resulting in the loss of dozens of lives. Many of these fatalities could have been averted had there been a reliable emergency communications system in place to provide life-saving information to search-and-rescue parties and to trapped miners. Past experience has shown that there is no practical way to harden infrastructure and ensure that the primary communications system (operating within conventional two-way radio bands) will survive any conceivable event. In practice, survivability must be achieved through alternative (secondary) communications paths. However, current technology requires large in-mine transmit antennas (100 ft.x100 ft.) and is limited in range due to the Mine Safety and Health Administration (MSHA) safety restrictions on permissible current flow in a coal mine environment. The National Institute for Occupational Safety and Health (NIOSH) supports research that leads to improvements in the safety and health of mine workers. In recent memory, a number of mine emergencies have had tragic consequences. Part of the fallout of these disasters has been the realization of the inadequacy of existing emergency mine communications. Traditional wireless radio systems are not designed for subterranean application and require a dedicated infrastructure to operate in a mine environment. This infrastructure is very likely to fail in mine emergencies such as fires, explosions, or roof cave-ins, resulting in complete loss of communication between trapped mine workers and the surface ground and rescue teams. On June 15, 2006, President George Bush signed the Mine Improvement and New Emergency Response (MINER) Act of 2006, which included the following statement: "The plan shall provide for a redundant means of communication with the surface for persons underground, such as secondary telephone or equivalent two-way communication." Current practices cover a wide range of electromagnetic bands, from UHF to ULF. Unfortunately, operating in any one of these bands has specific problems. To address this capabilities gap, Physical Optics Corporation (POC) initiated the development in Phase I of a Magnetic Through-The-Earth Miner Transceiver for Emergency Communications (MATHEMITE) system (Figure 1). The MATHEMITE system consists of a portable in-mine zero-power transmitter (ZPT) and a handheld battery-powered in-mine receiver unit that can provide reliable two-way TTE communication to a surface transceiver. This ZPT is based on mechanical rotation of permanent magnets. As a crank-shaft is rotated by the miner, a system of gears turns a system of high-strength permanent magnets at ultra low frequencies between 5 Hz and 15 Hz, optimal for long range through-the-earth (TTE) communication in a coal (or other) mine. Individual magnets within the transmitter rotate at different frequencies, with a unique ratio serving to identify the transmitter and distinguish it from environmental interference at the receiver on the surface (outside the mine). Because electrical power is not required and the transmissions generated by the ZPT are of extremely low frequency, it meets the MSHA electrical safety regulations for coal mine environments. In order to improve the efficiency of information transfer at low bit rates, MATHEMITE incorporates a novel message-encoding method based on commonly used words or phrases-rather than ASCII text-that results in at least a fourfold improvement in message transfer rate for 99.5% of messages. MATHEMITE also includes a mine receiver (a handheld device no larger than a walkie-talkie) that receives messages from a surface transmitter and displays them as text using less than 1 W of power. Operation in the 5-15 Hz band ensures that mine-to-surface communications can be maintained in all emergency situations-unlike current leaky feeder or medium frequency (MF) radios, which require unbroken tunnels or conducting lines. The in-mine unit requires no additional infrastructure for installation or operation in the mine environment. In Phase I, POC achieved all of the objectives set forth for this project for requirements analysis, system design, and feasibility demonstration with prototype systems in mine environments. In Phase I, we demonstrated the feasibility of MATHEMITE through mine tests with a scaled-down MATHEMITE system conducted at the Edgar Mine (Idaho Springs, CO), where we successfully recorded transmission through 385 ft and also distinguished individual transmitters from each other and from environmental noise signals. The prototype was demonstrated to technical personnel at the NIOSH Office of Mine Safety and Health Research (OMSHR) on July 13, 2012, by transmitting an S.O.S. signal in Morse code with the MATHEMITE prototype system from within the NIOSH Experimental Mine to a surface receiver 110 ft above the mine. In addition, the experimental results showed the feasibility of our novel approach to mitigating environmental interference and reducing false positives, based on unique frequency ratios. Experimental results showed good agreement with our system model, which allowed us to develop a full-scale design to meet the 2000 ft TTE communication range recommended by NIOSH OMSHR personnel. The above advantages also make the proposed transceiver commercially attractive, since it is based on the integration of existing technologies, and potential markets include not only mine safety but also construction and energy industries, in addition to numerous military and security applications. As a result, POC's proposed research will significantly impact the safety of personnel involved in underground operations by providing a reliable, compact, TTE communications system. Based on the success of the Phase I feasibility demonstration, POC developed a plan to complete the development of an MSHA-compliant MATHEMITE system and submitted a Phase II MATHEMITE proposal on August 5, 2012 based on this plan. [Description provided by NIOSH]
• Subjects:
  Emergencies Mining Occupational Health Safety
• Keywords:
  Communications Equipment Emergency Equipment Equipment Design Mine Disasters Mine Rescue Mining Industry Mobile Equipment Radio Waves Underground Mines
• Series:
  Grant Final Reports
• Publisher:
  National Institute for Occupational Safety and Health
• Document Type:
  Text
• Funding:
  Grant
• Genre:
  Final Grant Report
• Place as Subject:
  California ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  OEP - Office of Extramural Programs
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Pages in Document:
  1-19
• NIOSHTIC Number:
  nn:20059152
• NTIS Accession Number:
  PB2022-100316
• Citation:
  Atlanta, GA: U.S. Department of Health and Human Services, Public Health Service, Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, R43-OH-010143, 2012 Nov; :1-19
• Contact Point Address:
  Physical Optics Corporation, Applied Technologies Division, 1845 West 205th St., Torrance, CA 90501
• Federal Fiscal Year:
  2013
• NORA Priority Area:
  Mining
• Performing Organization:
  Physical Optics Corporation, Torrance, California
• Peer Reviewed:
  False
• Start Date:
  20110901
• Source Full Name:
  National Institute for Occupational Safety and Health
• End Date:
  20120831
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:d39d0ca81d29dc8f8e0ca8755184e39e9b4432e0aaa4ae879bd2bbecddc3d5245277c44fe25d9518441b6a0b13f711092c1110c24d84821a825c6b5f276b0bcf
• Download URL:
  https://stacks.cdc.gov/view/cdc/218968/cdc_218968_DS1.pdf
• File Type:
  [PDF - 1.04 MB ]