Few days ago, on CBS Nightly News, there was transmission from some
kind of Senate committe (attended among others by Mr. Bruce
Waltzman/NMA, Cecil Roberts/UMWA, J. Davitt McAteer/former federal
mine safety official and several more) investigating recent accidents
in coal mine.
One gentleman was helding in his hand something resembling a computer
mouse  and  was loudly claiming that this is already available miner's
tracking device COSTING ONLY $20.oo (!!!) which could save burried
miners.

Are there any working tracking devices that can locate burried miners
in distance over 25m (75ft)?

At this moment I'm very interested in systems  sending distress
signals from burried miners (transmitters and portable scanners), not
the one that warns miners about incoming danger.

I would appreciate answer especially from someone with practical expertise.

Thanks,

Andrew K.

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Request for Question Clarification by pafalafa-ga on 30 Jan 2006 12:56 PST

You might be interested to read the information collection request
just published by the Mine Safety and Health Administration:


http://www.msha.gov/REGS/FEDREG/PROPOSED/2006Prop/06-722.asp
Underground Mine Rescue Equipment and Technology; Proposed Rule 
Request for information


especially the section on "Communications" which says, in part:


...Current systems include permissible hand-held radios, hand-held
radios using small diameter wires, pager systems, sound powered
telephones, leaky feeder systems that ``leak'' radio signals out of
and into special cables, and inductive coupled radios that use
existing mine wires as a carrier for radio signals. Are there other
systems?


...PEDs are one-way communication devices that transmit text messages
through the earth to receivers which are carried by miners. PEDs are
currently being used in nineteen mines throughout the U.S. Should PEDs
be used even though they can only transmit signals to miners and are
not bi-directional? 9. Can PEDs be developed into 2-way systems? If
so, how long would it take and at what cost?


=====


So, it seems there are certainly available technologies, but they seem
to require existing wiring that can transmit from the mine depths to
the surface, a condition that may not exist in all mines.


I'm not sure which of the devices described above -- if any -- were
the ones referred to on CBS News.


Does this information help, at all?


pafalafa-ga

I heard about these (or similar) devices on the radio last week.  They
do exist, although the cost I heard was more like hundreds or
thousands per miner (that may include a necessary central system, as
well as the actual devices carried by the miners).  I'm not sure quite
how they work, as transmitting a signal though any distance of solid
rock is quite difficult.

The device in question was being displayed by Davitt McAteer, former
director of MSHA (mine safety and health administration).  It is
basically a pager.

He is correct in that the device itself is probably under $50 to
purchase.  However, he fails to mention that it requires "line of
sight" radio signals to work.  This requires a series of transmitters
or transponders to be located throughout a mine and these
transmitters/transponsders would be considered delicate in the rough
conditions experienced underground and would likely be destroyed in
the event of flood, fire or expolsion, thus rendering them useless.