Return-Path: Received: from mtain-dh12.r1000.mx.aol.com (mtain-dh12.r1000.mx.aol.com [172.29.65.32]) by air-db09.mail.aol.com (v129.4) with ESMTP id MAILINDB091-85f54d4a71fe1bd; Thu, 03 Feb 2011 04:14:38 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-dh12.r1000.mx.aol.com (Internet Inbound) with ESMTP id 723513800012D; Thu, 3 Feb 2011 04:14:36 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PkvFl-000722-ND for rs_out_1@blacksheep.org; Thu, 03 Feb 2011 09:13:25 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PkvFk-00071t-Tk for rsgb_lf_group@blacksheep.org; Thu, 03 Feb 2011 09:13:24 +0000 Received: from cavuit02.kulnet.kuleuven.be ([134.58.240.44]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PkvFi-0003Ko-6w for rsgb_lf_group@blacksheep.org; Thu, 03 Feb 2011 09:13:24 +0000 Received: from smtps02.kuleuven.be (smtpshost02.kulnet.kuleuven.be [134.58.240.75]) by cavuit02.kulnet.kuleuven.be (Postfix) with ESMTP id DAB2951C003 for ; Thu, 3 Feb 2011 10:13:11 +0100 (CET) Received: from ICTS-S-HUB-N2.luna.kuleuven.be (icts-s-hub-n2.luna.kuleuven.be [10.112.9.12]) by smtps02.kuleuven.be (Postfix) with ESMTP id CB2B2F3862 for ; Thu, 3 Feb 2011 10:13:11 +0100 (CET) Received: from ICTS-S-EXC2-CA.luna.kuleuven.be ([10.112.11.13]) by ICTS-S-HUB-N2.luna.kuleuven.be ([10.112.9.12]) with mapi; Thu, 3 Feb 2011 10:13:11 +0100 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Date: Thu, 3 Feb 2011 10:13:10 +0100 Thread-Topic: More earth-mode tests and a puzzle Thread-Index: AcvDMrOhc3g2kk49S4WvGaqGQCSyzwATIPGZ Message-ID: References: <0DF35BB8-9FC4-4A05-A9B9-675D74FEE669@gmail.com> In-Reply-To: <0DF35BB8-9FC4-4A05-A9B9-675D74FEE669@gmail.com> Accept-Language: nl-NL, nl-BE Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: nl-NL, nl-BE MIME-Version: 1.0 X-KULeuven-Information: Katholieke Universiteit Leuven X-KULeuven-Scanned: Found to be clean X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: RE: More earth-mode tests and a puzzle Content-Type: multipart/alternative; boundary="_000_BF4A524700075746A6467658DFC7102C88715AEB46ICTSSEXC2CAlu_" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30, HTML_FONTCOLOR_UNKNOWN,HTML_MESSAGE,TO_ADDRESS_EQ_REAL 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-sid: 3039ac1d41204d4a71fc0d26 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --_000_BF4A524700075746A6467658DFC7102C88715AEB46ICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hello Roger, congrats to you and G6ALB for this first succes. At 3km you are still within the near field (at a wavelength of 33km), so= the fact that the EFP works best might indicate that the transmit antenna= acts as an "electrical antenna" rather than as a small loop. If this is so the signal captured with the EFP will decrease with 40dB/dec= ade, so if you have 20dB SNR at 3km you will reach 0dB SNR at +/- 10km (as= suming same noise level). So if you could find a place "in the middle of= nowhere" (where noise is low) at about 10km you might be able to copy som= ething. Another thought: how the EFP signal outside the house ? if the signal if= much stronger inside the house this might indicate that the signal travel= s through the ground and is "brought up" by the house wirering and coupled= into the EFP. 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or= g] namens Roger Lapthorn [rogerlapthorn@gmail.com] Verzonden: donderdag 3 februari 2011 0:39 Aan: rsgb_lf_group@blacksheep.org Onderwerp: LF: More earth-mode tests and a puzzle This evening, during further tests looking for G6ALB's earth-mode beacon= signal on 8.76kHz, I discovered that best results receiving at my QTH 3km= from Andrew were with a small E-field probe rather than a loop or earth= electrode pair. With the EFP, signals could be detected in my upstairs sh= ack with just a 19inch whip! This suggests that the electrostatic componen= t is the dominant one rather than magnetic or simple potential difference= measurable between the 2 earth electrodes. My basic physics is very rusty= and any help clarifying what is going on would be appreciated. It now mea= ns we may have a much easier way of detecting utilities assisted earth-mod= e signals at greater ranges as the positioning of the EFP was far less cri= tical than trying to detect signals with a loop lying on the ground. Comments please? 73s Roger G3XBM Via my 2.4GHz handheld (iPod Touch 4g) --_000_BF4A524700075746A6467658DFC7102C88715AEB46ICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hello Roger,
 
 
congrats to yo= u and G6ALB for this first succes.
At 3km= you are still within the near field (at a wavelength of 33km), so the fac= t that the EFP works best might indicate that the transmit antenna ac= ts as an "electrical antenna" rather than as a small loop.
If this is so the signal captured wi= th the EFP will decrease with 40dB/decade, so if you have 20dB SNR at= 3km you will reach 0dB SNR at +/- 10km (assuming same noise level).= So if you could find a place "in the middle of nowhere" (where noise is low) at about 10km you might be able to copy something.
Another thought: how the EFP si= gnal outside the house ? if the signal if much stronger inside the house= this might indicate that the signal travels through the ground and is &qu= ot;brought up" by the house wirering and coupled into the EFP.
 
73, Rik  ON7YD - OR7T
 
 
Van: owner-rsgb_= lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Roger= Lapthorn [rogerlapthorn@gmail.com]
Verzonden: donderdag 3 februari 2011 0:39
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: LF: More earth-mode tests and a puzzle

This evening, during further tests= looking for G6ALB's earth-mode beacon signal on 8.76kHz, I discovered tha= t best results receiving at my QTH 3km from Andrew were with a small E-fie= ld probe rather than a loop or earth electrode pair. With the EFP, signals could be detected in my upstairs shack with= just a 19inch whip! This suggests that the electrostatic component is the= dominant one rather than magnetic or simple potential difference measurab= le between the 2 earth electrodes.=  My basic physics is very rusty and any help clarifying what is going on woul= d be appreciated. It now means we may have a much easier way of detecting= utilities assisted earth-mode signals at greater ranges as the positionin= g of the EFP was far less critical than trying to detect signals with a loop lying on the ground.

Comments please?

73s
Roger G3XBM

Via my 2.4GHz handheld (iPod Touch 4g)
--_000_BF4A524700075746A6467658DFC7102C88715AEB46ICTSSEXC2CAlu_--