TG MinerTrack^TM

 Information for MSHA regarding communications to trapped miners.

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Use of the TramGuard™ Proximity Detection System that was recently certified by MSHA can provide tracking of miners and communications Through-The-Earth to help save trapped miners during mine emergencies. Development of a Proximity Detection System has been the top priority safety initiative at MSHA during the last three years.  Now that miner tracking and communications during mine emergencies has also become a high priority, the TramGuard™ system can be used to accomplish multiple high priority objectives.

GMS demonstrated their TramGuard™ Proximity System late last year in a MSHA supervised field trial, working under an experimental permit, and obtained final I.S. approval and X/P approvals this month.  Tests were successfully performed at NIOSH on January 19 to demonstrate that this system can be used to transmit signals at the Ultra Low Frequencies that are required to penetrate the earth.  Further tests are planned soon to demonstrate transmissions Through-The-Earth (TTE) from inside a mine to the surface using the TramGuard™ system.

The ability to communicate TTE using Ultra Low Frequency oscillating magnetic fields was demonstrated by the Bureau of Mines in numerous experiments and studies 30 years ago.  The receiver that was used for the January 19 test at NIOSH was a unit that was manufactured as part of that program.

ULF TTE has been used for various purposes through the years.  However, modern digital communications were not available 30 years ago to make these systems as effective as is now possible.  Also, this earlier technology relied upon having a 280 foot wire stretched into a coil inside the mine, which can be operationally difficult and unreliable.  The TramGuard™ Proximity Detection System that was certified and approved this year includes modern microcontrollers and UHF transmitters and receivers and uses a ferrite in place of a 280 foot wire.

One of the key elements of the TramGuard™ Proximity Detection System is a Magnetic Field Generator that uses a large ferrite to produce a magnetic marker field around machinery, such as Continuous Miners.  This generator is housed inside an X/P cylinder.   By adjusting the frequency of the magnetic field generator to approximately 3,000 Hertz or less, signals can be sent through the earth from inside a mine. 

Another key element of the TramGuard™ system is a Personal Alarm Device that is carried by each miner.  The Personal Alarm Device is designed to automatically transmit Identification Codes, signals from the miners, and other information.  This information is received by a magnetic field generator which is then transmitted from inside the mine through the earth to receivers on the surface.

Each miner’s PAD automatically transmits information to any magnetic field generator within range.  In addition, the miner can use switches on his PAD to send signals and to command communications modes in the Magnetic Field Generator. 

When the miner is assigned a PAD, a record is made of the PAD I.D. number assignment.  The PAD transmits its I.D. and other information to any magnetic field generator (MFG) within range of the PAD, typically within approximately 200 feet line of sight.  It may be possible to extend this range.  MFGs will be positioned at selected locations within the mine.  If power is lost to the mine or is intentionally removed due to loss of ventilation, the MFGs will be automatically activated and begin transmitting a beacon once each 10 seconds.  The I.D. numbers for any miners within range will automatically be sent each five minutes.  An LED on the MFG will illuminate any time that TTE transmissions are being made.

If a miner within range of a MFG presses any of the three switches on his PAD, the beacon will switch to a faster mode and the beacon will then be sent each five seconds to let the rescue team on the surface know immediately that there is or was a miner within range of that MFG.  A miner can also press a switch on his PAD to send code messages or responses to communications received from the team on the surface above his location.  If the miner is sending messages, the transmission of the I.D. numbers will be suspended for a period of time so as to not conflict with ongoing communications.

Power is supplied to the Magnetic Field Generators by batteries that are contained within an X/P enclosure.  This battery PAK will transmit a beacon for approximately 10 days if no other communications is being sent through the MFG.  However, if the miner is continuously sending responses, the life of the batteries will be shortened somewhat.

Each PAD has its own small battery PAK which will operate continuously for at least three days.

Small, portable receivers and loop antennas are used above ground to detect and read the signals being sent from underground.  Once trapped miners are located, a borehole can be drilled to their location to supply air and communications.  Also, boreholes can be drilled in locations thought to be near trapped miners and a ULF receiver can be lowered into the borehole to detect ULF transmissions from the miners.  In addition, rescue teams can carry ULF receivers to detect MFG transmissions miners up to about two hundred yards away, even if they are behind a wall or pillars or roof falls.  Even if a miner is incapacitated, his PAD would continue to report his presence.

The MFGs are portable so that a miner can disconnect an MFG from the AC power that normally keeps the batteries charged and then take it with him as he seeks refuge or seeks to exit the mine.  

Mines are carefully surveyed so that the planned locations of a MFG can be marked on a map or even be marked on the surface above their locations.   Receivers can be taken to those locations to determine if miners are in that area or if they have been in that area since the emergency developed.  Repeaters could also be positioned at some or possibly all of those locations to report immediately to mine management any miners that are in the vicinity of any of the TG MineTrack Unit.

Communication needs to be in both directions between the miners and the personnel searching or rescuing them.  It is much easier to transmit from the surface to a receiver underground.  Powerful voice transmitters or signaling systems can be positioned near a MFG where miners are reported to be trapped or located and these high power transmissions can be detected with a small receiver.  Systems for transmitting voice and text messaging are already being used in some mines and could be used for this purpose.

The I.S. approved Personal Alarm Devices are already fully equipped and ready to perform the tasks and operations described above, with no changes required.  Since the ability to transmit the Ultra Low Frequencies from the TramGuard™ magnetic generators was demonstrated at NIOSH on January 19, the next step is to confirm that these transmissions will penetrate the earth with significant signal strength at the surface to be effectively utilized.  Most of the other functions described above are a matter of programming the micro-controllers in the MFGs.  Other features can be added by making other software changes.

It has been our plan at GMS, since the inception of the TramGuard™ development program, to use the system to track miners during normal operations.  The plan has been to record various kinds of information from each miner in the vicinity of the mobile equipments that have been outfitted with a T system.  This information was to be sent to a port to the mine communications system so that this information can routinely be sent to the surface to be monitored and recorded.  It has also been the plan to track miners in the mine during normal operations.  This would be accomplished by placing Magnetic Field Generators at strategic locations within the mine so that the passing of any miner would be recorded and his location would be routinely sent to the surface for recording or monitoring.  This would provide a realtime record of the approximate location of all personnel at all times.  From the beginning, the T system was architected to be able to provide these future capabilities.  The recent concern about the need for being able to communicate to trapped miners, as a result of recent mine disasters in West Virginia, motivated us to conceive of the above system modification to achieve through the earth communications, using the general concepts already built into the TramGuard™ System.

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