Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mb03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 0A4E838000082; Sat, 31 Mar 2012 10:42:50 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1SDzUI-000889-Mq for rs_out_1@blacksheep.org; Sat, 31 Mar 2012 15:41:06 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1SDzUI-000880-4J for rsgb_lf_group@blacksheep.org; Sat, 31 Mar 2012 15:41:06 +0100 Received: from filter02.i-online.fr ([195.200.78.9]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1SDzUH-0000qY-DL for rsgb_lf_group@blacksheep.org; Sat, 31 Mar 2012 15:41:06 +0100 Received: from smtp.qtxt.dns-iol.com ([195.200.78.13]) by filter02.i-online.fr (IceWarp 10.2.2) with ESMTP (SSL) id PRT99747 for ; Sat, 31 Mar 2012 16:40:47 +0200 Received: (qmail 11960 invoked by uid 507); 31 Mar 2012 16:40:53 +0200 Received: from unknown (HELO ?192.168.1.101?) (john.rabson@numeo.fr@217.67.155.178) by smtp.qtxt.dns-iol.com with SMTP; 31 Mar 2012 16:40:53 +0200 From: John Rabson Date: Sat, 31 Mar 2012 16:40:56 +0200 Message-Id: <09E42DF1-E8AD-4815-A393-0696858718DF@numeo.fr> Cc: Robin Gape , Chris Trayner , Rob Gill To: rsgb_lf_group@blacksheep.org Mime-Version: 1.0 (Apple Message framework v1257) X-Mailer: Apple Mail (2.1257) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,none Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: quoted-printable Subject: LF: Transmission characteristics of a two-wire telephone line X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.0 required=5.0 tests=none autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:454885024:93952408 x-aol-sid: 3039ac1d60174f7717ea274f X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none 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