Return-Path: Received: from mtain-mc02.r1000.mx.aol.com (mtain-mc02.r1000.mx.aol.com [172.29.96.74]) by air-db01.mail.aol.com (v129.4) with ESMTP id MAILINDB012-861b4d4a855e2fe; Thu, 03 Feb 2011 05:37:18 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mc02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 8C91938000090; Thu, 3 Feb 2011 05:37:16 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1PkwXf-0007Fm-9C for rs_out_1@blacksheep.org; Thu, 03 Feb 2011 10:35:59 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1PkwXe-0007Fd-DZ for rsgb_lf_group@blacksheep.org; Thu, 03 Feb 2011 10:35:58 +0000 Received: from mail-iw0-f171.google.com ([209.85.214.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1PkwXc-00040F-0l for rsgb_lf_group@blacksheep.org; Thu, 03 Feb 2011 10:35:58 +0000 Received: by iwn2 with SMTP id 2so939363iwn.16 for ; Thu, 03 Feb 2011 02:35:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:in-reply-to:references:date :message-id:subject:from:to:content-type; bh=HM8rIo/aHsBhavqNSfKgIuOXy00on04TajwI8DJTOfE=; b=jSOD+Pl/SmzD2ITKexqTk3ZEnBkKJTxKs87JCPwkpCgxbfdHZReCb5G7M0A89/+k0v wnJ7RsJIeBOj1LQ97QejFz6Qsdspv26VRLZoVEXIK+ZbysA29L8veGDO75iUZhnSp93f WChZOzYdNDj6YWKBzj7P3NWi6Lk1NoYbGHJpU= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :content-type; b=ity9VylpQSoleR9K/10vCFYyyf+YC4OnE9nMV1CqzFrTckNpeVUGcYjF9cnvveIuuF eYB/6+PmSbqe8Z2UpRRvRd3PsVXFZYyiBs5Fg3VZwUdqZxCTmqU2D6c+Rjcpwigt7Pom vPmD05E1z385ElxThM6cxtd9PqD5xgzsOVLE4= MIME-Version: 1.0 Received: by 10.42.178.195 with SMTP id bn3mr12479386icb.493.1296729349064; Thu, 03 Feb 2011 02:35:49 -0800 (PST) Received: by 10.42.241.73 with HTTP; Thu, 3 Feb 2011 02:35:49 -0800 (PST) In-Reply-To: References: <0DF35BB8-9FC4-4A05-A9B9-675D74FEE669@gmail.com> Date: Thu, 3 Feb 2011 10:35:49 +0000 Message-ID: From: Roger Lapthorn To: rsgb_lf_group@blacksheep.org DomainKey-Status: good (testing) X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: RE: More earth-mode tests and a puzzle Content-Type: multipart/alternative; boundary=90e6ba6e864c38875f049b5e54e0 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=HTML_FONTCOLOR_UNKNOWN, 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-AUTHENTICATION: mail_rly_antispam_dkim-m279.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d604a4d4a855c149d X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --90e6ba6e864c38875f049b5e54e0 Content-Type: text/plain; charset=ISO-8859-1 Hi Rik, I am pretty certain the signal is flowing along the water pipes but that the field *around* the pipes is much better detected with the E-field probe than with the loop. The EFP works very well outside in the street too and is far less critical about position and orientation. With the loop the signal is strong when clearly over the pipe work, whereas with the EFP one can, it seems, be almost anywhere in the road and house and get a signal. In the house I presume I am picking up the same sort of signal surrounding the pipes within the property. What I do NOT understand is why I get ZERO signal pick-up from G6ALB at 3km with another earth-electrode set-up at the RX end. One of my ground points is the copper central heating radiator which connects directly to metal pipes in the road. I know this as I use the same set-up to launch my own earth-mode signals that can be detected in the roads with a loop out in the fens >5km away. Logic tells me that if Andrew G6ALB is launching his signal along pipes from his earth electrode pair then I would get strongest signals by also connecting one ground to the metal pipework at the RX end, but this is definitely *not* the case as there is absolutely no signal detectable in QRSS3 by this method, but at least 20dB S/N with the EFP! Can someone explain what is going on please as I am very baffled! Tomorrow both G6ALB and I will put our beacons on (me on 8.7608kHz and G6ALB around 8.755kHz) and I will take a trip out into the fens with both the loop and the E-field probe to see what I detect. It is possible that with the EFP I may be able to detect the signal(s) at greater range than ever before on 8.76kHz. Incidentally, the pipe tracing papers I have read suggest that viewing the pipe as a conductor with a distributed capacitance to ground along its length lower frequencies will propagate further as the losses from this distributed capacitance to ground will be lower. This ties up with my own observation that signal levels at 5.3km distance are MUCH stronger on 0.838kHz than at 8.76kHz. I have still to try detection with an EFP at 0.838kHz. I really want to get on with my 4m transverter, but this VLF earth-mode stuff has become rather absorbing and time consuming. Having G6ALB locally also TXing now has added to the fun and ability to do meaningful experiments. By default we seem to have a band-plan for the Dreamer's Band: earth-mode around 8.76kHz and radiated around 8.97kHz. 73s Roger G3XBM On 3 February 2011 09:13, Rik Strobbe wrote: > 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/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 signal outside the house ? if the signal if > much stronger inside the house this might indicate that the signal travels > 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.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 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 shack > with just a 19inch whip! This suggests that the electrostatic component 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 means > we may have a much easier way of detecting utilities assisted earth-mode > signals at greater ranges as the positioning 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) > -- g3xbm-qrp.blogspot.com/ www.g3xbm.co.uk www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --90e6ba6e864c38875f049b5e54e0 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hi Rik,

I am pretty certain the signal is flowing along the water= pipes but that the field around the pipes is much better detected= with the E-field probe than with the loop. The EFP works very well outsid= e in the street too and is far less critical about position and orientatio= n. With the loop the signal is strong when clearly over the pipe work, whe= reas with the EFP one can, it seems, be almost anywhere in the road and ho= use and get a signal. In the house I presume I am picking up the same sort= of signal surrounding the pipes within the property.

What I do NOT understand is why I get ZERO signal pick-up from G6ALB= at 3km with another earth-electrode set-up at the RX end. One of my groun= d points is the copper central heating radiator which connects directly to= metal pipes in the road. I know this as I use the same set-up to launch= my own earth-mode signals that can be detected in the roads with a loop= out in the fens >5km away. Logic tells me that if Andrew G6ALB is laun= ching his signal along pipes from his earth electrode pair then I would ge= t strongest signals by also connecting one ground to the metal pipework at= the RX end, but this is definitely not the case as there is absolu= tely no signal detectable in QRSS3 by this method, but at least 20dB S/N= with the EFP! Can someone explain what is going on please as I am very ba= ffled!

Tomorrow both G6ALB and I will put our beacons on (me on 8.7608kHz and= G6ALB around 8.755kHz) and I will take a trip out into the fens with both= the loop and the E-field probe to see what I detect. It is possible that= with the EFP I may be able to detect the signal(s) at greater range than= ever before on 8.76kHz.

Incidentally, the pipe tracing papers I have read suggest that viewing= the pipe as a conductor with a distributed capacitance to ground along it= s length lower frequencies will propagate further as the losses from this= distributed capacitance to ground will be lower. This ties up with my own= observation that signal levels at 5.3km distance are MUCH stronger on 0.8= 38kHz than at 8.76kHz. I have still to try detection with an EFP at 0.838k= Hz.

I really want to get on with my 4m transverter, but this VLF earth-mod= e stuff has become rather absorbing and time consuming. Having G6ALB local= ly also TXing now has added to the fun and ability to do meaningful experi= ments.

By default we seem to have a band-plan for the Dreamer's Band: ear= th-mode around 8.76kHz and radiated around 8.97kHz.

73s
Roger G3= XBM

On 3 February 2011 09:13, Rik Strobb= e <Rik= .Strobbe@fys.kuleuven.be> wrote:
Hello Roger,
=A0
=A0
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=A0transmit antenna acts= 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=A020dB SNR at 3k= m you will reach 0dB SNR at +/- 10km (assuming same noise level). So if yo= u 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:=A0how the EFP signa= l outside the house ? if the signal if much stronger inside the house this= might indicate that the signal travels through the ground and is "br= ought up" by the house wirering and coupled into the EFP.
=A0
73, Rik=A0 ON7YD - OR7T
=A0
=A0
Van: owner-rsgb_lf= _group@blacksheep.org [owner-rsgb_lf_group@blacksheep.org] namens Ro= ger 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 eart= h-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 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.=A0My 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)



--
g3xbm-qrp.blogspot.com/
www.g3xbm.co.uk
= www.youtub= e.com/user/g3xbm
G3XBM=A0=A0 GQRP 1678= =A0=A0=A0 ISWL G11088
--90e6ba6e864c38875f049b5e54e0--