Return-Path: Received: from mtain-dd02.r1000.mx.aol.com (mtain-dd02.r1000.mx.aol.com [172.29.64.142]) by air-de07.mail.aol.com (v127_r1.1) with ESMTP id MAILINDE074-5ebd4b9a7c6efe; Fri, 12 Mar 2010 12:39:58 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dd02.r1000.mx.aol.com (Internet Inbound) with ESMTP id 7E1DD38000228; Fri, 12 Mar 2010 12:39:56 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Nq8m2-0007Oz-8T for rs_out_1@blacksheep.org; Fri, 12 Mar 2010 17:35:46 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Nq8m1-0007Oq-NR for rsgb_lf_group@blacksheep.org; Fri, 12 Mar 2010 17:35:45 +0000 Received: from mail-bw0-f215.google.com ([209.85.218.215]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Nq8lk-0005J4-3d for rsgb_lf_group@blacksheep.org; Fri, 12 Mar 2010 17:35:45 +0000 Received: by bwz7 with SMTP id 7so1283663bwz.4 for ; Fri, 12 Mar 2010 09:35:01 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:in-reply-to:references :date:message-id:subject:from:to:content-type; bh=99bqwOw0NNazbqMc1tvIAdFDTnXMeypB8BrWSVDyxmE=; b=jx2igHT/n6NHwPbyObnxQu6Mq86CViQrBtx1hpmIKM6WOt4I/PWgwhT1tYOkohPRyS 7LCyGk5JXvLpU8p0h3oaxZgIuVvgdMYSBwZrP9Doi/w4DD3ojufBsDgGvTXjjpNIuD1R wx6aRO98muhAEFJnE/RYE+oOpJpNhQDFnmBy0= 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=VGR4VrqTG0DXlpVc7GmvrajRKXcT+j07abTnAzEcg7d9sgoe5kImIRLP5MBD/jmYMd nyN5pXYLR4AWrnXOHl3EnFabIIk85tba/67r+CT3e+WUopp2XpxJLAcCXaz7OIK2JSYR HYlxRqK4Z+Z9kDKp4m3xNYGqg91khwn7KLqKM= MIME-Version: 1.0 Received: by 10.204.36.77 with SMTP id s13mr1787630bkd.42.1268415300860; Fri, 12 Mar 2010 09:35:00 -0800 (PST) In-Reply-To: <201003121541130296.0103EB1F@smtp2.numeo.fr> References: <130055.37036.qm@web28108.mail.ukl.yahoo.com> <201003121541130296.0103EB1F@smtp2.numeo.fr> Date: Fri, 12 Mar 2010 17:35:00 +0000 Message-ID: <9afca2641003120935j667296c9wd701fa2cc1e1b561@mail.gmail.com> 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: Induction DX? Content-Type: multipart/alternative; boundary=000325554e5a6f826604819df396 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_20_30,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-d275.1 ; domain : gmail.com DKIM : pass x-aol-sid: 3039ac1d408e4b9a7c6c7ef2 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --000325554e5a6f826604819df396 Content-Type: text/plain; charset=ISO-8859-1 Thanks John. Some good ideas at http://radiolocation.tripod.com/ . 73s Roger G3XBM On 12 March 2010 14:41, John RABSON wrote: > CREG members use loop-to-loop induction systems for determining underground > locations (particularly for establishing when the surface station is > vertically above the underground one). The transmitter emits a sequence of > beeps, usually on 874 Hz or 3496 Hz and is run off a small 9 V alkaline > battery. > > Brian Pease's site at http://radiolocation.tripod.com/ has a lot about > building and using equipment for this application. He says "Horizontal > range is on the order of several thousand feet and a depth of nearly 700 > feet has been done". > > Complete issues of CREGJ (ISSN 1361-4800) have not been placed on line > because of copyright problems. If you go to > http://bcra.org.uk/creg/jnl/index.html you can get contents lists for all > issues. Back numbers can be ordered. > > 73 John F5VLF/G3PAI > Formerly Commissioning Editor, Cave Radio & Electronics Group Journal > > *********** REPLY SEPARATOR *********** > > On 11/03/2010 at 13:45 M0FMT wrote: > > >Try > >http://www.marcspages.co.uk/tech/index.htm > >73 es GL petefmt > > > >--- On Thu, 11/3/10, Roger Lapthorn wrote: > > > > > >From: Roger Lapthorn > >Subject: LF: Induction DX? > >To: rsgb_lf_group@blacksheep.org > >Date: Thursday, 11 March, 2010, 20:54 > > > > > >If I've asked this before please forgive me.... > > > >With all the discussion recently on how to radiate a signal on sub-9kHz > >I'm left wondrering how far, practically, one could expect to get simply > >with sub-9kHz magnetic induction using multi-turn loops at each end? The > >Cave Radio Group (CREG) may have some answers but I'm not a subscriber so > >can't read any of their documents. > > > >It would be quite easy for anyone to generate 50-100W or so and feed this > >into a largish diameter multi-turn loop. Correctly aligned and with a > >similar loop at the far end and using decent weak signal processing just > >what range might be possible using modes like QRSS or WSPR? Has anyone > >tried this to see just what is practical, simply using induction fields? > > > >Also, can anyone point me to some webpages with some practical audio > >frequency induction communication systems? There are lots of references to > >near field comms for on-body and inter-device comms but I've not found > >much otherwise. > > > >73s > >Roger G3XBM > > > > > >-- > >http://g3xbm-qrp.blogspot.com/ > >http://www.g3xbm.co.uk > >http://www.youtube.com/user/G3XBM > >G3XBM GQRP 1678 ISWL G11088 > > > > > > -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/G3XBM G3XBM GQRP 1678 ISWL G11088 --000325554e5a6f826604819df396 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Thanks John. Some good ideas at http://radiolocation.tripod.com/ .

73s
= Roger G3XBM

On 12 March 2010 14:41, John= RABSON <john= .rabson@numeo.fr> wrote:
CREG members us= e loop-to-loop induction systems for determining underground locations (pa= rticularly for establishing when the surface station is vertically above= the underground one). =A0The transmitter emits a sequence of beeps, usual= ly on 874 Hz or 3496 Hz and is run off a small 9 V alkaline battery.

Brian Pease's site at http://radiolocation.tripod.com/ has a lot about buildi= ng and using equipment for this application. =A0He says "Horizontal= range is on the order of several thousand feet and a depth of nearly 700= feet has been done".

Complete issues of CREGJ (ISSN 1361-4800) have not been placed on line bec= ause of copyright problems. =A0If you go to =A0http://bcra.org.uk/creg/jnl/inde= x.html you can get contents lists for all issues. =A0Back numbers can= be ordered.

73 John F5VLF/G3PAI
Formerly Commissioning Editor, Cave Radio & Electronics Group Journal<= br>
*********** REPLY SEPARATOR =A0***********

On 11/03/2010 at 13:45 M0FMT wrote:

>Try
>http://www.marcspages.co.uk/tech/index.htm
>73 es GL petefmt
>
>--- On Thu, 11/3/10, Roger Lapthorn <rogerlapthorn@gmail.com> wrote:
>
>
>From: Roger Lapthorn <ro= gerlapthorn@gmail.com>
>Subject: LF: Induction DX?
>To: rsgb_lf_group@blac= ksheep.org
>Date: Thursday, 11 March, 2010, 20:54
>
>
>If I've asked this before please forgive me....
>
>With all the discussion recently on how to radiate a signal on sub-9kH= z
>I'm left wondrering how far, practically, one could expect to get= simply
>with sub-9kHz magnetic induction using multi-turn loops at each end?= =A0 The
>Cave Radio Group (CREG) may have some answers but I'm not a subscr= iber so
>can't read any of their documents.
>
>It would be quite easy for anyone to generate 50-100W or so and feed= this
>into a largish diameter multi-turn loop. Correctly aligned and with a<= br> >similar loop at the far end and using decent weak signal processing ju= st
>what range might be possible using modes like QRSS or WSPR? Has anyone=
>tried this to see just what is practical, simply using induction field= s?
>
>Also, can anyone point me to some webpages with some practical audio >frequency induction communication systems? There are lots of reference= s to
>near field comms for on-body and inter-device comms but I've not= found
>much otherwise.
>
>73s
>Roger G3XBM
>
>
>--
>http://g3= xbm-qrp.blogspot.com/
>http://www.g3xbm.= co.uk
>http:/= /www.youtube.com/user/G3XBM
>G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088








--

http://g3xbm-qrp.blogspot.com/http://www.g3xbm.co.uk
http://www.youtube.com/user/G3XBM
G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088
--000325554e5a6f826604819df396--