Return-Path: Received: from mtain-dc07.r1000.mx.aol.com (mtain-dc07.r1000.mx.aol.com [172.29.64.135]) by air-df01.mail.aol.com (v129.4) with ESMTP id MAILINDF014-5ee54c213ac8222; Tue, 22 Jun 2010 18:35:52 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dc07.r1000.mx.aol.com (Internet Inbound) with ESMTP id 57E3A38000103; Tue, 22 Jun 2010 18:35:46 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1ORC3J-0003H5-Qo for rs_out_1@blacksheep.org; Tue, 22 Jun 2010 23:34:45 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1ORC3J-0003Gw-4O for rsgb_lf_group@blacksheep.org; Tue, 22 Jun 2010 23:34:45 +0100 Received: from smtp5.freeserve.com ([193.252.22.159]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1ORC3I-00056M-6p for rsgb_lf_group@blacksheep.org; Tue, 22 Jun 2010 23:34:45 +0100 Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf3402.me.freeserve.com (SMTP Server) with ESMTP id 403991C02A31 for ; Wed, 23 Jun 2010 00:34:38 +0200 (CEST) Received: from me-wanadoo.net (localhost [127.0.0.1]) by mwinf3402.me.freeserve.com (SMTP Server) with ESMTP id 3347B1C02AF1 for ; Wed, 23 Jun 2010 00:34:38 +0200 (CEST) Received: from AGB (unknown [91.110.66.183]) by mwinf3402.me.freeserve.com (SMTP Server) with SMTP id 6EC9E1C02A31 for ; Wed, 23 Jun 2010 00:34:35 +0200 (CEST) X-ME-UUID: 20100622223435453.6EC9E1C02A31@mwinf3402.me.freeserve.com Message-ID: <0ECE5FE85EC44394BAECA33C98988E01@AGB> From: "Graham" To: References: In-Reply-To: Date: Tue, 22 Jun 2010 23:34:34 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 14.0.8089.726 X-MIMEOLE: Produced By Microsoft MimeOLE V14.0.8089.726 X-Antivirus: avast! (VPS 100622-1, 22/06/2010), Outbound message X-Antivirus-Status: Clean X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: VLF QRP Earth mode: 5.1km DX tonight but no such thing as a free lunch Content-Type: multipart/alternative; boundary="----=_NextPart_000_0016_01CB1263.78E4E480" 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_MESSAGE, MISSING_OUTLOOK_NAME 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: 3039ac1d40874c213ac2777a X-AOL-IP: 193.82.116.20 ------=_NextPart_000_0016_01CB1263.78E4E480 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Roger, Why not try ros mf-1 into the ground, that's based round 1 Khz= ? no need for a time locked pc ? G .. From: Roger Lapthorn=20 Sent: Tuesday, June 22, 2010 11:10 PM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: VLF QRP Earth mode: 5.1km DX tonight but no such thing as= a free lunch Second try at this post (without picture that may have been too large)= ...... Further tests today to work out how far a signal on 838Hz will propaga= te through the ground or air and how this happens. First thing I tri= ed was to go along the same country lane to the south of the village= as last evening at a distance of 4.2km (0.6km further than last night= ). Nothing, zero, ziltch, and disappointment.=20 So, I then returned to the very same spot as last night (3.6km) and su= re enough the QRSS3 signal was clearly visible on the Spectran display= . This was with the loop pointing home across the fields. Then the cru= nch point: I put the loop on the ground flat on the road and the signa= l went up. So, this was pretty conclusive proof that the signal was be= ing aided by pipework in the road. To check this, I moved 50m into a= field and away from the road and tried listening/looking for the QRSS= 3 signal with the loop both flat on the ground and facing home - nothi= ng at all. This was conclusive proof that, at this distance at least,= conduction through pipes was helping the signal reach this far. Next test was to go to a different roadside location some 4km west of= the QTH and try the same test again. Nothing copied at all, either wi= th the loop vertical or horizontally on the ground. I repeated the sam= e test on the way back towards home about 0.5km west of G6ALB's QTH,= but again nothing seen. Before coming home, slightly disappointed, I ventured up along a fenla= nd road where the soil is really dark peat. To my surprise, the signal= was copied again at good strength on the roadside 4.1km west of the= QTH with the loop facing the QTH. Again, I repeated the earlier test= and placed the loop horizontally on the ground. The signal was SO str= ong that the Spectran trace turned red and I could clearly hear the QR= SS3 signal by ear! =20 A drive up a road called Lord's Ground Drove resulted in the signal st= ill being copied well just beyond Lord's Ground Farm at a distance of= 5.1km. At this point I phoned my wife at home and asked her to switch= the TX over to 10wpm CW and the signal was recorded with Spectran and= clearly audible with the narrow filters in. Using the crystal earpiec= e instead of the PC I was not able to hear the CW in the 50Hz noise.= Listen to this recording at 5.1km from the TX but use narrow filters= around 838Hz to hear the 10wpm beacon signal clearly. CONCLUSIONS 1.. At local distances (up to 0.5km) the signal propagates by both= conduction through the ground (aided by pipes in the ground) and by= induction (proved by the orientation of the loop when well away from= roads and pipes)..=20 2.. At greater distances (3-5kms) the signal reaches its destination= by conduction through the ground aided by pipes in the roads and with= inductive coupling into the loop at the RX.=20 3.. There is no evidence of induction playing a real (long distance)= part in propagation at 5.1km distance.=20 4.. When the signal is being "utility coupled" the direction with re= spect to the TX earth electrode pair (and loop formed in the ground)= is not important. What matters more is whether there are metal pipes= between the TX and RX locations; if these are not present then the si= gnal will not be received, I think, at any great distance. There is so= me possibility that coupling may also be possible as a result of overh= ead cables, but this has not been tested. 5.. Even allowing for the conduction aided by pipes, I am amazed tha= t just a 4W TX into a 20m baseline earth electrode pair can be copied= so well at 5.1km (and probably considerably further), and even more= surprised that 10wpm CW copy was possible at this range.=20 6.. "Utility coupling" aided VLF earth mode communications could be= very viable over a range of at least 5kms. FURTHER WORK 1.. Try an E-field probe at 5km and greater distance. It should reje= ct 50Hz noise more and may work as well as the loop? 2.. Try to establish the limit of true induction communications unai= ded by ground conduction paths.=20 3.. Sea coast earth mode test with one electrode in the water and th= e other at the TX end, say, 100m inland from the water's edge. Just ho= w far would you be able to receive the signal along the coast using an= other electrode pair or an induction loop? So, some useful further tests, but some disappointment. "There is no= such thing as a free lunch", as they say. For real VLF work Stefan's= true radiation experiments are where the action REALLY is. All good fun and I've learnt a lot. There's a screen shot of the recei= ved QRSS3 signal (strong!) plus the recording of the 10wpm CW signal= at 5.1kms on my earth mode website . 73s Roger G3XBM --=20 http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 ------=_NextPart_000_0016_01CB1263.78E4E480 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Roger,
 
Why not  try  ros mf-1 into= the =20 ground,  that's  based round  1 Khz  ? no need&nbs= p; for a=20 time locked  pc  ?
 
G ..

Sent: Tuesday, June 22, 2010 11:10 PM
Subject: LF: VLF QRP Earth mode: 5.1km DX tonight but no= such thing=20 as a free lunch

Second=20 try at this post (without picture that may have been too=20 large)......

Further tests today to work out how far a= signal on=20 838Hz will propagate through the ground or air and how this=20 happens.   First thing I tried was to go along= the same=20 country lane to the south of the village as last evening at a distance= of 4.2km=20 (0.6km further than last night). Nothing, zero, ziltch, and disappoint= ment.=20


So, I then returned to the very same spot as last ni= ght=20 (3.6km) and sure enough the QRSS3 signal was clearly visible on the Sp= ectran=20 display. This was with the loop pointing home across the fields. Then= the crunch=20 point: I put the loop on the ground flat on the road and the si= gnal went=20 up. So, this was pretty conclusive proof that the signal was being aid= ed by=20 pipework in the road. To check this, I moved 50m into a field and away= from the=20 road and tried listening/looking for the QRSS3 signal with the loop bo= th flat on=20 the ground and facing home - nothing at all. This was conclusive proof= that, at=20 this distance at least, conduction through pipes was helping the signa= l reach=20 this far.

Next test was to go to a different roadside location= some 4km=20 west of the QTH and try the same test again. Nothing copied at all, ei= ther with=20 the loop vertical or horizontally on the ground. I repeated the same= test on the=20 way back towards home about 0.5km west of G6ALB's QTH, but again nothi= ng=20 seen.

Before coming home, slightly disappointed, I ventured up= along a=20 fenland road where the soil is really dark peat. To my surprise, the= signal was=20 copied again at good strength on the roadside 4.1km west of the= QTH with=20 the loop facing the QTH. Again, I repeated the earlier test and placed= the loop=20 horizontally on the ground. The signal was SO strong that the Spectran= trace=20 turned red and I could clearly hear the QRSS3 signal by ear! 
A=20 drive up a road called Lord's Ground Drove resulted in the signal stil= l being=20 copied well just beyond Lord's Ground Farm at a distance of 5.1km. At=20 this point I phoned my wife at home and asked her to switch the TX ove= r to 10wpm=20 CW and the signal was recorded with Spectran and clearly audible with= the narrow=20 filters in. Using the crystal earpiece instead of the PC I was not abl= e to hear=20 the CW in the 50Hz noise. Listen to this recording at 5.1km from the TX<= /A> but use narrow=20 filters around 838Hz to hear the 10wpm beacon signal=20 clearly.

CONCLUSIONS
  1. At local distances (up to 0.5km) the signal propagates by both= conduction=20 through the ground (aided by pipes in the ground) and by induction= (proved by=20 the orientation of the loop when well away from roads and pipes)..= =20
  2. At greater distances (3-5kms) the signal reaches its destination= by=20 conduction through the ground aided by pipes in the roads and with= inductive=20 coupling into the loop at the RX.=20
  3. There is no evidence of induction playing a real (long distance)= part in=20 propagation at 5.1km distance.=20
  4. When the signal is being "utility coupled" the direction with re= spect to=20 the TX earth electrode pair (and loop formed in the ground) is not= important.=20 What matters more is whether there are metal pipes between the TX an= d RX=20 locations; if these are not present then the signal will not be rece= ived, I=20 think, at any great distance. There is some possibility that couplin= g may also=20 be possible as a result of overhead cables, but this has not been te= sted.
  5. Even allowing for the conduction aided by pipes, I am amazed tha= t just a=20 4W TX into a 20m baseline earth electrode pair can be copied so well= at 5.1km=20 (and probably considerably further), and even more surprised that 10= wpm CW=20 copy was possible at this range.=20
  6. "Utility coupling" aided VLF earth mode communications could be= very=20 viable over a range of at least 5kms.
FURTHER WORK
  1. Try an E-field probe at 5km and greater distance. It should reje= ct 50Hz=20 noise more and may work as well as the loop?
  2. Try to establish the limit of true induction communications unai= ded by=20 ground conduction paths.=20
  3. Sea coast earth mode test with one electrode in the water and th= e other at=20 the TX end, say, 100m inland from the water's edge. Just how far wou= ld you be=20 able to receive the signal along the coast using another electrode= pair or an=20 induction loop?
So, some useful further tests, but some= =20 disappointment. "There is no such thing as a free lunch", as they say.=   For=20 real VLF work Stefan's true radiation experiments are where the action= REALLY=20 is.

All good fun and I've learnt a lot. There's a screen shot= of the=20 received QRSS3 signal (strong!) plus the recording of the 10wpm CW sig= nal at=20 5.1kms on my earth mode website .

73s
Roger= G3XBM


--
http://g3xbm-qrp.blogspot.co= m/
http://= www.g3xbm.co.uk
http://www.youtube.com/user/g3xbm
G3XBM &nbs= p;  GQRP=20 1678      ISWL G11088


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