Return-Path: Received: from mtain-de10.r1000.mx.aol.com (mtain-de10.r1000.mx.aol.com [172.29.64.210]) by air-mc06.mail.aol.com (v129.4) with ESMTP id MAILINMC063-a9754d4aeeeb3c1; Thu, 03 Feb 2011 13:07:39 -0500 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-de10.r1000.mx.aol.com (Internet Inbound) with ESMTP id E4FDC380000AF; Thu, 3 Feb 2011 13:07:37 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Pl3ZE-0000He-6z for rs_out_1@blacksheep.org; Thu, 03 Feb 2011 18:06:04 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Pl3ZC-0000HV-P1 for rsgb_lf_group@blacksheep.org; Thu, 03 Feb 2011 18:06:02 +0000 Received: from out1.ip04ir2.opaltelecom.net ([62.24.128.240]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Pl3ZA-000812-MA for rsgb_lf_group@blacksheep.org; Thu, 03 Feb 2011 18:06:02 +0000 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AtcBAN98Sk1cEYfn/2dsb2JhbACSYwODYo5lc71ahVgEgWCNTYJt X-IronPort-AV: E=Sophos;i="4.60,421,1291593600"; d="scan'208,217";a="322911274" Received: from unknown (HELO xphd97xgq27nyf) ([92.17.135.231]) by out1.ip04ir2.opaltelecom.net with SMTP; 03 Feb 2011 18:05:53 +0000 Message-ID: <004b01cbc3cc$feffc1f0$0401a8c0@xphd97xgq27nyf> From: "mal hamilton" To: References: Date: Thu, 3 Feb 2011 18:05:52 -0000 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2600.0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2600.0000 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: LF: Re: Earth-mode or not earth-mode Content-Type: multipart/alternative; boundary="----=_NextPart_000_0048_01CBC3CC.FEBAA2A0" 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-sid: 3039ac1d40d24d4aeee905e1 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0048_01CBC3CC.FEBAA2A0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Roger There are lots of places to experiment with so called earth mode out= in the countryside, it is not impossible, but if you live in an envi= ronment that is swamped with a criss cross of buried cables and pipes= then this is not a hobby for so called earth mode communications. Strangely enough only a small % of the UK is swamped by urban developm= ent. Most of the urban development is in concentrated areas and there= are vast areas of undeveloped wide open spaces. From what you say you= are in a hostile urban swamp and if you are serious about VLF I think= you would need to move, comfortable as you might be otherwise=20 As regards the question about launching a respectible signal on LF/VLF= then its simple, Plenty of power and an Elevated antenna. de G3KEV I=20 ----- Original Message -----=20 From: Roger Lapthorn=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Thursday, February 03, 2011 5:12 PM Subject: LF: Earth-mode or not earth-mode Thanks for feedback and questions from Rik, Chris, Mal, Stefan and= others on and off this list.=20 I'm still waiting for someone to explain to me why, if this is (main= ly) conduction along metal pipes, which I am sure it is, best results= are not obtained with a galvanic connection to the pipe at each end= and why best receive results are with an E-field probe. I remain puzz= led. Answers please! May I reply on a few general points raised by some? What is the definition of earth-mode? I could not find one, but my understanding is "communication between= two points essentially using conduction through the ground". In the= modern world it is almost impossible to find anywhere, except remote= moors, that is not criss-crossed with buried cables and pipes. My int= erpretation of earth-mode therefore includes utilising these as a mean= s of helping a signal get from (a) to (b). Hence my term "utilities as= sisted earth-mode". In mining and military use of earth-mode I think= this is also accepted. What I also mean is communicating from (a) to= (b) not using a radiated signal or induction as the prime means of pr= opagation.=20 Why experiment with this form of VLF/ULF communication?=20 From my tests last year it was clear that local communication "piggy= -backing" on these buried utilities seemed to be possible over many ki= lometres without the need for large and complex antenna systems that= are essential to get even a tiny VLF signal actually radiated, as Oss= i, Gerhard, Stefan and Chris know only too well.=20 Questions I'm trying to answer are: a.. How best to launch a signal?=20 b.. What in the ground (apart from water, soil and rock) helps the= signal get from (a) to (b)? c.. What works best to pick up the VLF/ULF signal at the far end= of the link? d.. What frequencies work best? e.. What are the noise sources and how can these be minimised? f.. How close to buried utilities does one really have to be for= it to work?=20 g.. Can one use rivers, canals or the sea coast for earth-mode?=20 h.. How little/much power is needed for a given range? i.. What modes are most effective? j.. What is the practical range limit? k.. Is there a practical use for this form of communication? Also, I'd welcome suggestions for further practical tests. A lot of= the experience is directly useful in the reception of DX radiated VLF= signals.=20 Results have been shared here because others are known to be interes= ted in this aspect of VLF work, but if people think the LF-reflector= is not the right place please say so.=20 73s Roger G3XBM --=20 g3xbm-qrp.blogspot.com/ www.g3xbm.co.uk www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 ------=_NextPart_000_0048_01CBC3CC.FEBAA2A0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Roger
There are lots of places to experiment with so= called=20 earth mode out in the countryside, it is not impossible, but if you li= ve in=20 an  environment that is swamped with a criss cross of buried cabl= es and=20 pipes then this is not a hobby for so called earth mode=20 communications.
Strangely enough only a small % of the UK is= swamped by=20 urban development. Most of the urban development is in concentrated ar= eas and=20 there are vast areas of undeveloped wide open spaces. From what= you say you=20 are in a hostile urban swamp and if you are serious about VLF I think= you would=20 need to move, comfortable as you might be otherwise
As regards the question about launching a resp= ectible=20 signal on LF/VLF then its simple, Plenty of power and an Elevated= =20 antenna.
de G3KEV
 
 
I 
----- Original Message -----
Sent: Thursday, February 03,= 2011 5:12=20 PM
Subject: LF: Earth-mode or no= t=20 earth-mode

Thanks for feedback and questions from Rik, Chris, Ma= l, Stefan=20 and others on and off this list.

I'm still waiting for so= meone to=20 explain to me why, if this is (mainly) conduction along metal pipes,= which I=20 am sure it is, best results are not obtained with a galvanic= connection=20 to the pipe at each end and why best receive results are with an E-f= ield=20 probe. I remain puzzled. Answers please!

May I reply on= a few=20 general points raised by some?

What is the definition of=20 earth-mode?

I could not find one, but my understandin= g is=20 "communication between two points essentially using conduction th= rough the=20 ground". In the modern world it is almost impossible to find any= where,=20 except remote moors, that is not criss-crossed with buried cables an= d pipes.=20 My interpretation of earth-mode therefore includes utilising these= as a means=20 of helping a signal get from (a) to (b). Hence my term "utilities as= sisted=20 earth-mode". In mining and military use of earth-mode I think this= is also=20 accepted. What I also mean is communicating from (a) to (b) not using a=20 radiated signal or induction as the prime means of propagatio= n.=20

Why experiment with this form of VLF/ULF communication= ?=20

From my tests last year it was clear that local comm= unication=20 "piggy-backing" on these buried utilities seemed to be possible over= many=20 kilometres without the need for large and complex antenna systems th= at are=20 essential to get even a tiny VLF signal actually radiated, as= Ossi,=20 Gerhard, Stefan and Chris know only too well.

Questions I'm= trying to=20 answer are:
  • How best to launch a signal?=20
  • What in the ground (apart from water, soil and rock) helps the= signal=20 get from (a) to (b)?
  • What works best to pick up the VLF/ULF signal at the far end= of the=20 link?
  • What frequencies work best?
  • What are the noise sources and how can these be minimised?
  • How close to buried utilities does one really have to be for= it to work?=20
  • Can one use rivers, canals or the sea coast for earth-mode?
  • How little/much power is needed for a given range?
  • What modes are most effective?
  • What is the practical range limit?
  • Is there a practical use for this form of=20 communication?
Also, I'd welcome= suggestions=20 for further practical tests.  A lo= t of the=20 experience is directly useful in the reception of DX radiated= VLF=20 signals.

Results have been shar= ed here=20 because others are known to be interested in this aspect of VLF work= , but if=20 people think the LF-reflector is not the right place please= say so.=20


73s
Roger G3XBM

--
g3xbm-qrp.blogspot.com/
www.g3xbm.co.uk
ww= w.youtube.com/user/g3xbm
G3XBM   GQRP 1678    ISWL=20 G11088
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