This weekend myself and one of my chums headed into darkest Cornwall to drop a reasonable sized shaft. The shaft is about 40 - 50 meters deep, laddered (some fairly dodgy) with intermediate stagings and pretty wet. I went first and bottomed the shaft without issues. Having called rope free I waited for my chum to follow. Unbeknown to me he was having issues up at surface; given the depth of the shaft and the noise of the water he couldn't let me know. After about fifteen minutes with no sign of him I decided to head back up, although given the problems with communication I couldn't let him know. As I am packing rope on one of the ladder platforms my mate starts faffing with the rope and dislodges a timber, which plummets down the shaft nearly taking me out; oh how I laughed.

Our joint performance in the shaft was pretty pathetic, largely due to non existent communication. How could we have done it better? For example would walkie talkies work given that line of sight was obscured by timber stagings?

Yeah, sounds like comms would be very handy.

Walkie Talkies would probably have done you fine if they were an appropriate set.

Avoid VHF underground as the waves are quite large and will only fit in large tunnels (a shaft would be ok), UHF is generally better underground and the waves can rattle quite a way down tunnels but they won't go through rock.

Those PMR446 radios are licence free but limited to 0.5 watts transmission, and most of the cheaper versions won't even do that. You can get a set of cheap UHF walkie talkies from ebay etc with rated outputs of 5+ watts that will go a lot further on account of the stronger transmission.

Ideally program them to the PMR446 frequencies rather than just making up a random number as it will limit the mischief you could cause. Though be aware transmitted on the PMR446 channels on more that 0.5w isn't legal. But if you're underground, your transmission won't be leaving the mine.

If it was me I'd consider the lesser of the evils. Compromising personal safety in a hazardous environment by slashing the radio power so they might not reach, or what is, in my opinion, a rather minor and arguably justifiable creative bending of the spectrum licencing regulations.

Or use loud whistles? or a field phone if you can be bothered running a wire?

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There is a system of whistle blasts used. Look up “technical skills for proficient cavers” and there it a section on communication.

We could borrow a couple of walkie talkies from work to test out on Thursday night.
The last time we could have used such a system there was a lot of running water making it impossible to communicate by shouting. I doubt if whistles would have worked there but foghorns might.

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MARK

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UHF is alright underground so long as its not going through rock.

I had these two American things once, they worked quite high up (around 1ghz) at 2 watts. They were digital and encrypted. They were basically rugged mobile phones that could also work unit-to-unit. I got them on eBay.

I mention them because they were very good underground. The smaller wave seems to bounce some distance especially if the walls are wet.

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I've certainly been on winch trips in shafts where field telephones were set up but I guess that would be a bit excessive for a one off explore.

Maybe just arrange a system for Baulks of timber dropped down the shaft since that sounds like it got your attention.

One crashing down - I'm beginning to descend.

Two crashing down - I don't fancy this any more I've gone to the pub.

etc.

Anyhow, glad you survived, see you at NAMHO?

I've certainly been on winch trips in shafts where field telephones were set up but I guess that would be a bit excessive for a one off explore.

Maybe just arrange a system for Baulks of timber dropped down the shaft since that sounds like it got your attention.

One crashing down - I'm beginning to descend.

Two crashing down - I don't fancy this any more I've gone to the pub.

etc.

Anyhow, glad you survived, see you at NAMHO?

;D

Yes I'll be at NAMHO along with the usual crew. If nothing else I am looking forward to taking the p*ss out of your new van 😉

Yeah, sounds like comms would be very handy.



Those PMR446 radios are licence free but limited to 0.5 watts transmission, and most of the cheaper versions won't even do that. You can get a set of cheap UHF walkie talkies from ebay etc with rated outputs of 5+ watts that will go a lot further on account of the stronger transmission.

Ideally program them to the PMR446 frequencies rather than just making up a random number as it will limit the mischief you could cause. Though be aware transmitted on the PMR446 channels on more that 0.5w isn't legal. But if you're underground, your transmission won't be leaving the mine.

The 5w versions above perform very well in shafts. Especially
if a length of wire can be safely dangled down the shaft.
Just hold the "fixed" radio in close proximity to the wire & the "mobile" set should get good copy while it's moved up/down the shaft.
Not easily do-able in a shaft with staging etc. but otherwise a very worthwhile improvement over no wire. Similar system (with their licensed radios) tested / used by some CROs.

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Yeah, sounds like comms would be very handy.



Those PMR446 radios are licence free but limited to 0.5 watts transmission, and most of the cheaper versions won't even do that. You can get a set of cheap UHF walkie talkies from ebay etc with rated outputs of 5+ watts that will go a lot further on account of the stronger transmission.

Ideally program them to the PMR446 frequencies rather than just making up a random number as it will limit the mischief you could cause. Though be aware transmitted on the PMR446 channels on more that 0.5w isn't legal. But if you're underground, your transmission won't be leaving the mine.

The 5w versions above perform very well in shafts. Especially
if a length of wire can be safely dangled down the shaft.
Just hold the "fixed" radio in close proximity to the wire & the "mobile" set should get good copy while it's moved up/down the shaft.
Not easily do-able in a shaft with staging etc. but otherwise a very worthwhile improvement over no wire. Similar system (with their licensed radios) tested / used by some CROs.

A lot of shafts have pipes already running down 😃

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We did some tests once with walkie talkies. I think we were at the 100m shaft at Croesor which is large and empty. Results were poor, and we gave up there or thereabouts. Unfortunately I can't remember the frequency or output power.
We just shout a lot now.

Chris.

We have used walkie-talkies fairly recently, indeed last year!
On a large 30m+ Shaft in Ireland, other than old guy who is writing this and inclined to make mistakes with new technology, it worked very well.
Will try and get Robert to post up the details.
Must admit they worked very well.

I use vhf walkie talkies when sailing, these are typically 5W, would be very surprised if they couldn't transmit from top to bottom of a 40 metre shaft.

Yes I'll be at NAMHO along with the usual crew. If nothing else I am looking forward to taking the p*ss out of your new van ;)

I may be disappointing you by bringing the normal tent/Celica combo along with its ever increasing reliance on cable ties.

I figure this may be easier than trying to park a small bungalow at various roadside meeting points.

I never go anywhere these days without taking at least a couple of Walkie Talkies.
The ones I tend to use are the16 channel Baofeng 888, Pronounced 'Bow - as in sharp end of a boat, and Fung.

They work on the licence free 446 MHz band (UHF) and kick out about 2 Watts, but personally I think closer to 3Watts.
They arrive with a mains charger and cradle, (now with USB charging lead as well) a removable 1500mA Lithium ion battery, a clip on earpiece with built in microphone for hands free operation and removable antenna.
It even has a small LED (find your keys or get you out the sh1t) lamp.
Not bright but better then nothing.

Straight out the box they are generally programmed to the offshore 446 channels which are illegal in UK and could interfere with other services, so reprogramming is essential for trouble free operation.
The programming lead costs between £3 to £7 and the programming software -CHIRP - is free on line along with reviews, user manual and stuff they don't tell you in the manual etc.

http://www.miklor.com/BF888/ 

These sets can also be programmed with a scrambler, which can be applied to individual channels or to all.
I have mine programmed for channels 1 to 8 straight and channels 9 to 16 scrambled.

They are not waterproof but work well in plastic bags, and audio quality is superb.

Cost ? these are ridiculously cheap considering build, performance and user friendliness, £19.00 a pair ! 😮 :thumbup:
Available as single units or as multiple packs.

https://www.ebay.co.uk/itm/2x-BaoFeng-BF-888S-Walkie-Talkie-UHF-400-470MHZ-2-Way-Ham-Radio-16CH-Long-Range/112337112045?hash=item1a27d04bed:g:FgsAAOSw9NBaVLjK 

These are well built bits of kit and will take being dropped without exploding into uncountable component parts, unlike the 'Kiddie Toys' you find elsewhere.

I cannot recommend them enough.

NOTE - Don't be tempted to buy the Baofeng UV 5R. This is purely an amateur radio transceiver, and you could quite easily find yourself broadcasting on frequencies that could get you into very hot water, such as the Maritime Coastguard Agency :o

🔗114561[linkphoto]114561[/linkphoto][/link]


🔗114562[linkphoto]114562[/linkphoto][/link]

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I've a pair of those as well, which I've used in shafts.
Cracking little set & the batteries seem fine too. Had mine for about 3 years with no problem.
Got the UV5 as well which I use on the 2m & 70cm amateur bands. Likewise good set for the money but unless your licenced, avoid as Roy says.

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Motorola i355 - I remember it now.

They are (were) a rugged mil-spec cell phone from the US which only worked on one particular network there, which eventually went bust, so the phones are useless as phones.

But they have a walkie-talkie feature which is highly sophisticated and has earned them a bit of a legendary status. They can talk unit-to-unit like a normal walkie-talkie but it's digital and highly encrypted. It also frequency-hops many times a second in a pattern known only to these phones.

They are extremely popular even today with drug dealers, assassins, terrorists, gangsters and prisoners as a means of communicating with colleagues securely and privately. I had a pair and found they worked well underground, being a small wave up around 950mhz I think.

They are not legal in this country of course. Or anywhere really.

http://r.ebay.com/AXahGK 

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Motorola i355 - I remember it now.

They are (were) a rugged mil-spec cell phone from the US which only worked on one particular network there, which eventually went bust, so the phones are useless as phones.

But they have a walkie-talkie feature which is highly sophisticated and has earned them a bit of a legendary status. They can talk unit-to-unit like a normal walkie-talkie but it's digital and highly encrypted. It also frequency-hops many times a second in a pattern known only to these phones.

They are extremely popular even today with drug dealers, assassins, terrorists, gangsters and prisoners as a means of communicating with colleagues securely and privately. I had a pair and found they worked well underground, being a small wave up around 950mhz I think.

They are not legal in this country of course. Or anywhere really.

http://r.ebay.com/AXahGK 

Puts a new slant on qualifying for the Int. Amateur Radio Union WAC award - Worked All Criminals ;D


(it's Continents really)

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What about air horns?
I'm thinking, fairly cheap, anyone could use one, no batteries, not affected by water, no fiddly buttons covered in mud etc.
Is there a downside?

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