LF: Transmission characteristics of a two-wire telephone line

[John Rabson <john.rabson@numeo.fr>]

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