Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 047EC3800009D; Fri, 24 Jun 2011 05:40:50 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Qa2qm-0002uW-Jn for rs_out_1@blacksheep.org; Fri, 24 Jun 2011 10:38:56 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Qa2ql-0002uN-Ld for rsgb_lf_group@blacksheep.org; Fri, 24 Jun 2011 10:38:55 +0100 Received: from filter02.i-online.fr ([195.200.78.9]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Qa2qk-0000B3-7T for rsgb_lf_group@blacksheep.org; Fri, 24 Jun 2011 10:38:55 +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 HPK39639 for ; Fri, 24 Jun 2011 11:38:39 +0200 Received: (qmail 10895 invoked by uid 507); 24 Jun 2011 11:38:44 +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; 24 Jun 2011 11:38:44 +0200 From: John Rabson Mime-Version: 1.0 (Apple Message framework v1084) Date: Fri, 24 Jun 2011 11:38:45 +0200 In-Reply-To: To: rsgb_lf_group@blacksheep.org References: Message-Id: <54EE765A-DBFE-475A-8D27-0D51E233D308@numeo.fr> X-Mailer: Apple Mail (2.1084) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Content-Type: multipart/alternative; boundary=Apple-Mail-43--111355669 Subject: Re: LF: Earth mode and pipes 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=HTML_MESSAGE 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: 0:2:473111936:93952408 X-AOL-SCOLL-URL_COUNT: 0 x-aol-sid: 3039ac1d41164e045ba273a1 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --Apple-Mail-43--111355669 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=us-ascii All sorts of things happen at lower frequencies, and some of them are = not easily explained. A few years ago, one of the caving journals = reported that a group of cavers, who were several hundred metres below = the surface somewhere in southern Europe, had received BBC R4 on 198 kHz = although the signal was not audible on the surface.=20 On a somewhat higher frequency (31 m broadcast) I once received Radio = Nederland at good strength when I was between 30 and 100 m below the = surface in the Yorkshire Dales. No other stations were received at any = strength in that band. One of my colleagues, professionally engaged in = radio communications, suggested there might be some sort of fault in the = rock. This was probably true, but we were unable to determine whether = that caused the unusual propagation. John F5VLF On 23 Jun 2011, at 10:43CEST, Roger Lapthorn wrote: > It is some while since I last did any earth mode (conduction through = the ground) tests although I intend to resume these in a few weeks' time = after my holiday to Iceland. One of the tests will be earth mode at much = higher frequencies such as around 30 and 70kHz as well as at even lower = frequencies below 100Hz. I will try not to trigger WW3 by TXing around = 82Hz though. >=20 > Today I noticed some workmen in the road outside my house with = measuring kit and listening gear. They were checking for leaks in water = pipes which occur usually where sections of pipe are linked. As I'd = always assumed my earth mode was utilities assisted via the metal water = pipes from my house and in the road I asked the question what sort of = pipes were in the road. I was surprised to hear these are not metal at = all but are asbestos cement pipes. The did not believe any tracer wires = were present either. >=20 > So, I am a bit puzzled now about what exactly my earth mode signals = are coupling into. All the indications were that I was using the water = pipes but now I have some doubts. The other utilities in the road are = electricity, gas and CATV which is fibre optic. Phones come in via = overhead wires. I think the answer is that the coupling to buried = utilities must be more complex than I had assumed and that the earth = mode signal is coupled into a variety of pipes and cables.=20 >=20 > 73s > Roger G3XBM >=20 > --=20 > http://g3xbm-qrp.blogspot.com/ > http://www.g3xbm.co.uk > http://www.youtube.com/user/g3xbm > https://sites.google.com/site/sub9khz/ >=20 --Apple-Mail-43--111355669 Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset=us-ascii All = sorts of things happen at lower frequencies, and some of them are not = easily explained.   A few years ago, one of the caving journals = reported that a group of cavers, who were several hundred metres below = the surface somewhere in southern Europe, had received BBC R4 on 198 kHz = although the signal was not audible on the = surface. 

On a somewhat higher frequency (31 m = broadcast) I once received  Radio Nederland at good strength when I = was between 30 and 100 m below the surface in the Yorkshire Dales. =  No other stations were received at any strength in that band. =  One of my colleagues, professionally engaged in radio = communications, suggested there might be some sort of fault in the rock. = This was probably true, but we were unable to determine whether that = caused the unusual propagation.

John = F5VLF


On 23 Jun 2011, at 10:43CEST, = Roger Lapthorn wrote:

It is some = while since I last did any earth mode (conduction through the ground) = tests although I intend to resume these in a few weeks' time after my = holiday to Iceland. One of the tests will be earth mode at much higher = frequencies such as around 30 and 70kHz as well as at even lower = frequencies below 100Hz. I will try not to trigger WW3 by TXing around = 82Hz though.

Today I noticed some workmen in the road outside my house with = measuring kit and listening gear. They were checking for leaks in water = pipes which occur usually where sections of pipe are linked. As I'd = always assumed my earth mode was utilities assisted via the metal water = pipes from my house and in the road I asked the question what sort of = pipes were in the road. I was surprised to hear these are not metal at = all but are asbestos cement pipes. The did not believe any tracer = wires were present either.

So, I am a bit puzzled now about what exactly my earth mode signals = are coupling into. All the indications were that I was using the water = pipes but now I have some doubts. The other utilities in the road are = electricity, gas and CATV which is fibre optic. Phones come in via = overhead wires.  I think the answer is that the coupling to buried = utilities must be more complex than I had assumed and that the earth = mode signal is coupled into a variety of pipes and cables.

73s
Roger G3XBM

--
http://g3xbm-qrp.blogspot.com/
http://www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
https://sites.google.com/site/sub9khz/


= --Apple-Mail-43--111355669--