Google "Cave Radio" and "CREG" to learn about specialized low freq cave
communications systems which would have helped in this scenario. Much of
this development is going on overseas.

The word I heard was that the conventional radio system in the mine
failed after the explosion.

It is a shame that the miners don't have a communications system, an
oxygen source and refuge other than a "curtain" under these situations.

My wife and I stayed up watching the "miracle" until it was found untrue
and were quite shocked.

Joe

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"Hamguy" wrote:



KC8VKZ


very sad situation:

Kind of strange they don't have any kind of decent ( even primitive)
comm system in place in the mines


Each miner should be carrying personal communications like
firefighters.


The problem with that being that when they are two miles deep in the
mine,
radio comms are all but worthless. To get comms for the rescue workers,
they
had to relay by radio from two points, then by wire from the last relay
point to the command center. One might suggest repeaters every so often,
but
these could easily be damaged or destroyed during an explosion or
cave-in.


I thought there were some freq which would pass thru rocks and earth to
great depths. LF perhaps, but that would present other problems. There
must be some way for them to reliably communicate other than by wire.



Lowfer comms require extensive antenna arrays that are not feasible in these
situations. About the only thing I can think of would be to place wired
communications systems with the wires in heavy conduit which is in turn set
into the cave walls and covered with steel and concrete. Perhaps something
like that could reliably survive most hazards of underground mining
(especially if set into the cave floor rather than the walls).





--
Joe Leikhim K4SAT
"The RFI-EMI-GUY"©

"Treason doth never prosper: what's the reason?
For if it prosper, none dare call it treason."

"Follow The Money" ;-P