Walkie talkies / underground comms

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simonrl
51% (Neutral)
Administration Topic Starter

17 years ago

From the backup lights thread...

"bograt" wrote:
talking of backups just to move off topic slightly how well do walky talkies work underground,ive been toying with taking my radio shacks down for a try,does the rock soak up the signal or can it get round the passages (i know nothing about this subject) or do those newfangled digital ones work down there.

my orders are to sit here and watch the world go by

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mountainpenguin
50.2% (Neutral)
Newbie

17 years ago

The cave rescue have a number of heyphones. These have interesting characteristics and tend to work better in wet caves rather than dry mines. I do intend to experiment with these in the slate mines again in more depth when I am well again.
As for radio's as long as there is line of site they should work but as soon as you loose line of site they will probably fail. Others can probably tell you more of their experiences with CB's and PMR radios.
The instructions and parts list for the HeyPhone is available online though I have not looked at the legal side of using it for not CRO situations.

http://bcra.org.uk/creg/heyphone/documentation.html would be a good place to start

patch
50.2% (Neutral)
Newbie

17 years ago

I was in a working gypsum mine a week ago and noticed that everyone carried some sort of communication device (it looked like 2-way radio). I asked if it worked ok underground and the answer was "somethimes, depends where you are".
The mine works at a depth of 1000ft and is worked on the pillar and stall method with a ceiling height of up to 32 feet. The headings are over a mile from the portal.
If anyone wants, I can make enquires as to what sort of comms system they use.

Don't wait for a light to appear at the end of the tunnel, stride down there and light the damn thing yourself

AdM Michael
50.2% (Neutral)
Newbie

17 years ago

Widely used in mines:

leaky feeder or or leaky cable where you have a long antenna following you round the mine and you're never further than a few metres away from it on the designated routes

or

repeater stations placed at regular intervals. Look up Pennine Telecom
http://www.penninetelecom.com/radio.aspx?page=74
for more information. The system is in use at several miscellaneous mines in the UK

Mr Mike
50.2% (Neutral)
Newbie

17 years ago

"simonrl" wrote:
From the backup lights thread...

"bograt" wrote:
talking of backups just to move off topic slightly how well do walky talkies work underground,ive been toying with taking my radio shacks down for a try,does the rock soak up the signal or can it get round the passages (i know nothing about this subject) or do those newfangled digital ones work down there.

I have used the standard Motorola outdoor ones down big shafts and they worked. Even along parts of dogleg bends. Used them for the first time descending Frog Shaft at Nent, as contact would have been impossible due to water noise.

Mr Mike www.mineexplorer.org.uk

sparty_lea
50.2% (Neutral)
Newbie

17 years ago

Yes I've used cheapo walkie talkies descending wet shafts and they work ok in the shaft itself and you can usually manage a signal just about out of the falling water at the bottom. No good away from the bottom of the shaft though.

Probably not a good idea if you're somewhere you shouldn't be either, TWICE we've got crossed signals with other users, must be loads of people using them for various stuff.

There are 10 types of people in the world.

Those that understand binary and those that do not!

ChrisJC
50.2% (Neutral)
Newbie

17 years ago

We tried cheapo ones on the Croesor shaft, 100m top to bottom. They didn't work. And it's a straight shaft.

Chris.

Mr Mike
50.2% (Neutral)
Newbie

17 years ago

I admit that we only tested up to around 50m, as there were various landing points. However, there was a lot of pipe work in as well, and they did still hold up well.

Mr Mike www.mineexplorer.org.uk

Gwyn
50.2% (Neutral)
Newbie

17 years ago

I could never figure out why my mobile 'phone had a full, usable signal at the lake level in Penrhyn. Odd one.

davel
50.2% (Neutral)
Newbie

17 years ago

#10

The Cave Radio and Electronics Group (CREG) http://bcra.org.uk/creg/ , which is a special interest group of The British Cave Research Association (BCRA), have done research on this topic.

If I remember correctly John Rabson, who is the CREG contact for general enquiries (and who used to be a colleague of mine at the BT Research Labs in Suffolk), has done work with hand-held walkie-talkies, including tests in at least some of the Blaenau underground slate quarries. His email address can be found on the CREG home page.

Dave

Dark Prince
50.2% (Neutral)
Newbie

17 years ago

#11

Them cheap Motorola PMR ones work ok in the Brewery Shaft in Nenthead way, which given the situation i was in was bloody lucky!.

The main thing to remember is the cheap ones work on line of site. If you can see the person you are talking to, they should work over longish distances. I've got a pair sat next to me that have done 3KM from hill top to hill top. but ask them to work in a concrete grandstand at work between 2 floors and you've got no chance.

Not used them much U/G, just tend to shout louder!!.

DP

Redwinch
50.2% (Neutral)
Newbie

17 years ago

#12

Used a standard Rotel CB unit (FM) in the winch cab, a hand held motorolla unit at the shaft top and the same unit slightly modified on the winch chair. mods were waterproofing, steel body and aerial replaced by wire attatched to winch steel cable. worked ok even though winch was about 30 yds away from shaft collar.

Still supporting Rampgill. last time I looked