Hello.

Just use a pair of hdsl Modems
And a router and you'll have
A data circuit on top of The POTS
Line.

73
Giorgio

Inviato da iPhone

Il giorno 31/mar/2012, alle ore 16:40, John Rabson <[email protected]> ha 
scritto:

> I have received an enquiry from an Italian caver about using such a line to 
> transmit speech, text and images of unspecified characteristics from one 
> underground location to another. It is not clear whether the cable will be in 
> a tunnel or in a cave.
> 
> The total cable length is about 800 metres.  For speech communications, his 
> team intends to use field telephones (which are obviously going to work 
> okay), but he would like to be able to transmit other things. I have sent him 
> copies of a couple ofCREGJ articles on underground video, but before I can 
> advise him further I need some appreciation of the attenuation versus 
> frequency characteristics of the type of line he wishes to use.
> 
> Can anyone advise, please?
> 
> John F5VLF
> 
> 
>