Cheap Fixes for Mine Cave-In Communications Blackouts
Blackwater
by: Me
Do you get the feeling that American coal/mineral mines
are inspected by the same people who check highway bridges ?
The recent Utah mine cave-in and other similar incidents
have shown that a reliable way for rescuers and miners to
communicate would be highly desireable. Too often there is
little clue as to where miners might take shelter in a
large complex or as to their condition and immediate needs.
Conventional communications methods are generally worthless
in a deep mine. Cell phones and common radios won't work
because of the shielding effect of the earth and/or ores.
Wired communications lines are generally cut during a
serious cave-in - be they conventional wired telephones
or phones that use ore-car tracks as 'wires'. Even the
convention of tapping on walls or rails is often rendered
useless.
However, one relatively simple and inexpensive technology
that can facilitate communications does exist - VLF or ELF
radio (Very-Low-Frequency / Extremely-Low-Frequency).
ELF radio is used by the US Navy to communicate with
submarines. Where high-frequency radio waves tend to
skim the earths, beam into space or are simply absorbed
by earth and water, low-frequency radio waves can
easily penetrate THROUGH earth and water.
There are two downsides to VLF/ELF radio. The first is
because low frequencies mean long wavelengths - thus a
very long antennat is needed for medium/long-range
transmission. Submarines trail a wire antenna, possibly
a mile long.
The second issue is data-transmission capability. Data,
be it voice or code, requires modulation of the radio
signal. Either its strength (amplitude) or frequency or
both have to be twiddled. At the low frequencies there
isn't much "room" to modulate the signal before you're
out of the bandspace entirely. ELF uses frequencies of
only 30 Hz to 3 kHz ... the equivalent of a deep bass
note to vocal-range tones. VLF runs from 3 kHz to 30 kHz.
Very little modulation can be applied to such signals,
they're literally radio waves in the audio-spectrum
zone as opposed to 550-1600 kHz for AM broadcast radio
or megahertz fequencies for CBs, portable phones, police
and avaiation radios and such.
It's easy to superimpose an audio-frequency variant on
a megahertz-frequency radio signal. Not so with a radio
signal that's an even lower freqency than most audio.
Military ELF/VLF communications generally just turn
the signal on and off to achieve a sort of Morse-code
effect. Data comes in at only a couple of characters
per second at best - slower than the slowest typist.
Voice ? Forget it !
So how to get around these problems ?
First of all, since we're talking short ranges, we can
skip the mile-long antennas. Ordinary slug-loaded coil
antennas (take apart an old AM radio - it's the long
black bar with a coil of wire around it) would serve OK
under those conditions. Not efficient, but who cares ?
Secondly, since we're interested in penetrating rock
instead of seawater, we can probably use the "higher"
frequencies - maybe up to five or eight kHz. This
gives us a *little* room for some kind of modulation.
Now here's where modern technology is a big help. It IS
possible to put a voice signel even on VLF radio - but
you have to "cheat". The trick is to forget about "real
time" back and forth banter. Instead you store speech
in a small memory buffer and then, slowly, encoded it
into as much modulation as your VLF channel CAN handle.
It literally may come across almost as "Morse code",
switching the signal on and off, or represent only a
one percent change in signal frequency.
Neverthless, the voice signal CAN be encoded. It's
just very, very *slow*. The miner would speak a sentence
and then wait awhile - maybe a minute or two. Aboveground
the reciever would translate the code back into an audio
signal. When enough of the message had been translated,
it would 'speak' it electronically in that famous 'Stephen
Hawking' electrovoice style. A reply could be sent to
the miner in the same way. Think of it as using a cockroach
to carry small written notes back and forth.
Using voice is better than trying to have the miners use
a keyboard terminal. Dust and smoke and eye irritants may
make it impossible to even SEE a keyboard or LCD screen
after a cave-in. Such embelishments also add to the cost
and create more things that can break.
A VLF radio with such voice-encoding technology would not
be very expensive to make. The unit plus battery pack
could be fit into a 1-foot-square "telephone boxes" that
can be placed in various places within the mine. As an
added safety feature against dead batteries, each unit
should have power taps to which miners could jury-rig
batteries from common equipment they already carry.
Keeping the units cheap means that mine owners (who seem
to be notorious tightwads) would have no excuse NOT to
have them. It wouldn't even be a burden for government
regulations to require such units - or unions to demand
them. While not "perfect" because of the slow communication
speed, slow is one HELL of a lot better than "none".
- - -
There's another alternative that might be useful in some
kinds of mines - "magnetic" communication. Solid-state
devices for detecting magnetic fields have become
exquisitely sensitive of late. Consider a "radio" which
isn't much more than a microphone feeding a single
amplifying transistor - which is connected to a coil
of wire around a metal beam. Speaking into the mic
generates a magnetic field which is modulated at
the same frequency as the incoming voice. The reciever
is an almost identical rig - but uses a sensitive
magnetometer to pick up the incoming signal, turning
it back into a voice.
This wouldn't work well in a deep mine if there were
lots of iron deposits, but it might be OK for a coal
mine. Not quite as good as my proposed VLF communcations
system, but even cheaper.
Voice signals can also be transformed into sound frequencies
that DO carry through fractured rock. VL(a)F "very low
audio frequency" communications is also possible using
mechanical transducers to send vibrations through the
rock.
- - -
Anyway, there are three ideas to deal with the communcations
problem in mine disasters. They're all quite simple, robust
and inexpensive to implement. I can't be the first one to
think of this - SO WHY DON'T WE *SEE* THESE ALREADY ???
Ask your congressman. Ask your local mine-workers union.
Ask your local mine owner. No excuses.
Bert Hyman
news:46bb2c97...@news.east.earthlink.net:
> Do you get the feeling that American coal/mineral mines
> are inspected by the same people who check highway bridges ?
You don't trust government bureaucrats and politicians to look out
for you?
--
Bert Hyman | St. Paul, MN | be...@iphouse.com
Blackwater
>b...@barrk.net (Blackwater) wrote in
>news:46bb2c97...@news.east.earthlink.net:
>
>> Do you get the feeling that American coal/mineral mines
>> are inspected by the same people who check highway bridges ?
>
>You don't trust government bureaucrats and politicians to look out
>for you?
What, ME worry ?
Impmon
>> Do you get the feeling that American coal/mineral mines
>> are inspected by the same people who check highway bridges ?
>
>You don't trust government bureaucrats and politicians to look out
>for you?
Same bureaucrats who let a rapist (who fucked a 7 year old girl)
because they couldn't be bothered to find an interprentor for an
obsecure language.
99% of the time these government don't bother me. It's that 1% like a
$4,000 wrench that makes me wish I could just pack up and move.
--
sa...@platshop.com disgust me. sa...@platshop.com spams a lot in game
so I am posting sa...@platshop.com as often as possible so sa...@platshop.com
would start getting spammed sa...@platshop.com eye for an eye. for good
luck, sa...@platshop.com and sa...@platshop.com
Blackwater
>On 09 Aug 2007 15:06:39 GMT, Bert Hyman <be...@iphouse.com> wrote:
>
>>> Do you get the feeling that American coal/mineral mines
>>> are inspected by the same people who check highway bridges ?
>>
>>You don't trust government bureaucrats and politicians to look out
>>for you?
>
>Same bureaucrats who let a rapist (who fucked a 7 year old girl)
>because they couldn't be bothered to find an interprentor for an
>obsecure language.
That law generally improves the fairness of the justice
system. On rare occasion it can have undesired consequences
but that doesn't mean it's bad law. For every perp that
walks free on 'technical' grounds, 1000 more will get
fair, uncontestable, trials.
>99% of the time these government don't bother me. It's that 1% like a
>$4,000 wrench that makes me wish I could just pack up and move.
Um ... you CAN.
But move WHERE ? For all its faults, the USA ain't bad.
Euros live a more controlled existence and don't have
as much spendin' money either. China ? Indonesia ?
Anywhere in Africa ? Syria ? Russia ? The slums of
San Paulo ? Sorry, no 'perfect' places to go. None
even close to 'perfect'. Better to stick with the
devils you know ...
Charles
"Blackwater" <b...@barrk.net> wrote in message
news:46bb8377...@news.east.earthlink.net...
> But move WHERE ? For all its faults, the USA ain't bad.
> Euros live a more controlled existence and don't have
> as much spendin' money either. China ? Indonesia ?
> Anywhere in Africa ? Syria ? Russia ? The slums of
> San Paulo ? Sorry, no 'perfect' places to go. None
> even close to 'perfect'. Better to stick with the
> devils you know ...
Exactly ... the USA is actually much better than "ain't bad." Why else
would we be dealing with a flood of immigrants (both legal and illegal)?
Gerard Bok
wrote:
>Miners/Rescuers Don't Have To Be "In The Dark" After Disasters :
>by: Me
>Conventional communications methods are generally worthless
>in a deep mine.
>Anyway, there are three ideas to deal with the communcations
>problem in mine disasters. They're all quite simple, robust
>and inexpensive to implement. I can't be the first one to
>think of this - SO WHY DON'T WE *SEE* THESE ALREADY ???
Because your story misses a vital ingredient, I guess.
All the tricks you describe would require at least several Watts
to operate. (And don't be surprised if it turns out to be
'several hundreds of Watts')
And would require --weak point in the mining industry--
conciderable investments.
My 2 cents: Hitting the wall with a stone has saved several
trapped workers in the last century.
It may well prove to be the lifesaver for the next.
--
Kind regards,
Gerard Bok
Blackwater
Well now ... I don't see a flood of Canadians riding
rabid moose across the border ........
Part of our problem is that one border is smack up
against a 2nd-world country ... which is smack up
against a whole bunch of 2nd/3rd-world countries.
It's not that the USA is so overwhelmingly great,
just that it's so RELATIVELY great in comparison to
points south.
Oh yea, and because so many business owners WANT that
cheap, exploitable labor and are able to block any
effective efforts to cut off the tide of 'Mexicans'.
(Admittedly though, most of the "Mexicans" put our
domestic workforce to shame - hardworking and
energetic. Maybe THAT'S part of the reason they
are so diskliked - they SHAME us, show us just
how lazy and jaded we have become)
The biggest problem is states where illegals can claim
a big 'welfare' package just by showing up. That's going
a bit TOO far.