Return-Path: <owner-rsgb_lf_group@blacksheep.org> Received: from mtain-mc06.r1000.mx.aol.com (mtain-mc06.r1000.mx.aol.com [172.29.96.78]) by air-dd04.mail.aol.com (v129.4) with ESMTP id MAILINDD044-86ac4bfcdf852ea; Wed, 26 May 2010 04:44:53 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mc06.r1000.mx.aol.com (Internet Inbound) with ESMTP id B010238000090; Wed, 26 May 2010 04:44:51 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OHCDM-0002V8-Ts for rs_out_1@blacksheep.org; Wed, 26 May 2010 09:43:48 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OHCDM-0002Uz-Eq for rsgb_lf_group@blacksheep.org; Wed, 26 May 2010 09:43:48 +0100 Received: from mail-bw0-f43.google.com ([209.85.214.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from <rogerlapthorn@gmail.com>) id 1OHCDJ-0002zf-LB for rsgb_lf_group@blacksheep.org; Wed, 26 May 2010 09:43:48 +0100 Received: by bwz16 with SMTP id 16so1497623bwz.16 for <rsgb_lf_group@blacksheep.org>; Wed, 26 May 2010 01:43:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:mime-version:received:received:in-reply-to :references:date:message-id:subject:from:to:content-type; bh=yF4NKgecPykfmRv4DDOG8ASJTfgPnKofToZXd1w3x/o=; b=DBxwSXTRome+XLfBS655ur8MoKHaJGnsjMFctm0Ao+BlELl/t7e11vxeWLwwdkg2Pv r0PTNjAxgNs38jKEubfeu09SaRMz48KnM6JNbSjasK1QzkzkD6tH/nopKo8OQI0OV+0P yvlzZkWVtfq89s9KftyjLv87OXUWoKEx6EfGg= 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=VeUFBy1s39gWUFT94WuKmuRN2EO6nirfZ9qGl8cLSd4i3jnVHAKOu+FceAmQGIJTgU VMQ1YC/VOR5N0AVj48gH+jloDBkr8aA746apdkJzaPsEArz/+xM98GP0krQoUU6P7pHD 6vjazdkvHRTyNH7dStsV4eHFN4VviZyrauhSY= MIME-Version: 1.0 Received: by 10.204.6.5 with SMTP id 5mr356214bkx.152.1274863424511; Wed, 26 May 2010 01:43:44 -0700 (PDT) Received: by 10.204.58.204 with HTTP; Wed, 26 May 2010 01:43:44 -0700 (PDT) In-Reply-To: <BF4A524700075746A6467658DFC7102C5106464EEA@ICTS-S-EXC2-CA.luna.kuleuven.be> References: <AANLkTinG-0mJJ3CDqFwxeLXfOJXFFfs42gjLYz8yX3rW@mail.gmail.com> <38A51B74B884D74083D7950AD0DD85E82A1C00@File-Server-HST.hst.e-technik.tu-darmstadt.de> <AANLkTilyd93InqPvp5qUVkonthTgtMaIVqVfH3zyen2B@mail.gmail.com> <Pine.LNX.4.64.1005252313060.26690@paranoid.lipkowski.org> <AANLkTimudswbmeqd9Ej52egRUOJ4RHIf5VtYiQ7_7d8T@mail.gmail.com> <BF4A524700075746A6467658DFC7102C5106464EEA@ICTS-S-EXC2-CA.luna.kuleuven.be> Date: Wed, 26 May 2010 09:43:44 +0100 Message-ID: <AANLkTimXcAWlXyxfo4gAThfv3maPkFNyKK6HYMNRxhk3@mail.gmail.com> From: Roger Lapthorn <rogerlapthorn@gmail.com> 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: AW: 8.97kHz - Near field and radiated signals? Content-Type: multipart/alternative; boundary=0015174ff3528e21d004877b45a9 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-sid: 3039ac1d604e4bfcdf830437 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --0015174ff3528e21d004877b45a9 Content-Type: text/plain; charset=ISO-8859-1 Rick (et al), I am confused by the near field attenuation rates quoted. Some quote *18dB for doubling distance* which would mean an additional path loss of 56dB going from 0.4km to 3km. This makes a lot of difference to what may or may not be possible. Which is the correct figure? Help! 73s Roger G3XBM On 26 May 2010 09:31, Rik Strobbe <Rik.Strobbe@fys.kuleuven.be> wrote: > Roger, > > > > the near fiels signal drops with the 3rd power of the distance. > > So 3km versus 0.4km = 422 times weaker = -26dB > > Going from regular CW to QRSS30 will give you a 24dB benefit, so there is a > fair chance to be copied at 3km in this mode. Of course the signal needs to > be very frequency stable, it has to be better than an free running > oscillator. > > Moving up in frequency would also help. > > And if you can lay your hands on an old stereo amp it would provide an > extra 10dB TX power. > > > > Even if your goal is regular CW over a 3km path, starting with QRSS will > most likely give a visible signal at 3km and allow you to watch any > progress. > > > > 73, Rik ON7YD - OR7T > > > >> - The best DX targets are quite modest: I would like to exceed 1km >> >> initially with the TX power I currently have (around 4W). If I could >> reach >> G6ALB in the next village 3kms away I would be delighted. If I got any >> further I would be both amazed and VERY happy! >> > -- http://g3xbm-qrp.blogspot.com/ http://www.g3xbm.co.uk http://www.youtube.com/user/g3xbm G3XBM GQRP 1678 ISWL G11088 --0015174ff3528e21d004877b45a9 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Rick (et al),<br><br>I am confused by the near field attenuation rates quo= ted. Some quote <b>18dB for doubling distance</b> which would mean an addi= tional path loss of 56dB going from 0.4km to 3km. This makes a lot of diff= erence to what may or may not be possible.<br> <br>Which is the correct figure? Help!<br><br>73s<br>Roger G3XBM <br><br><= br><div class=3D"gmail_quote">On 26 May 2010 09:31, Rik Strobbe <span dir= =3D"ltr"><<a href=3D"mailto:Rik.Strobbe@fys.kuleuven.be">Rik.Strobbe@fy= s.kuleuven.be</a>></span> wrote:<br> <blockquote class=3D"gmail_quote" style=3D"margin: 0pt 0pt 0pt 0.8ex; bord= er-left: 1px solid rgb(204, 204, 204); padding-left: 1ex;"> <div> <div style=3D"font-family: Tahoma; direction: ltr; color: rgb(0, 0, 0); fo= nt-size: 13px;"> <p>Roger,</p> <p><font face=3D"tahoma" size=3D"2"></font>=A0</p> <p><font face=3D"tahoma" size=3D"2">the near fiels signal drops with the= 3rd power of the distance.</font></p> <p><font face=3D"tahoma" size=3D"2">So 3km versus 0.4km =3D 422 times weak= er =3D -26dB</font></p> <p><font face=3D"tahoma" size=3D"2">Going from regular CW to QRSS30 will= give you a 24dB benefit, so there is a fair chance to be copied at 3km in= this mode. Of course the signal needs to be very frequency stable, it has= to be better than an free running oscillator.</font></p> <p><font face=3D"tahoma" size=3D"2">Moving up in frequency would also help= .</font></p> <p><font face=3D"tahoma" size=3D"2">And if you can lay your hands on an ol= d stereo amp it would provide an extra 10dB TX power.</font></p> <p>=A0</p> <p><font face=3D"tahoma" size=3D"2">Even if your goal is regular CW over= =A0a 3km path, starting with QRSS will most likely give a visible signal= at 3km and allow you to watch any progress.</font></p> <p><font face=3D"tahoma" size=3D"2"></font>=A0</p> <p><font face=3D"tahoma" size=3D"2">73, Rik=A0 ON7YD - OR7T</font></p><div= class=3D"im"> <p><font face=3D"tahoma" size=3D"2"></font>=A0</p> <font face=3D"tahoma" size=3D"2"> <blockquote style=3D"border-left: 1px solid rgb(204, 204, 204); margin: 0p= t 0pt 0pt 0.8ex; padding-left: 1ex;" class=3D"gmail_quote"> <p>=A0- The best DX targets are quite modest: I would like to exceed 1km= </p> <div><br> =A0initially with the TX power I currently have (around 4W). If I could re= ach<br> =A0G6ALB in the next village 3kms away I would be delighted. If I got any<= br> =A0further I would be both amazed and VERY happy!</div> </blockquote> </font></div></div> </div> </blockquote></div><br><br clear=3D"all"><br>-- <br><a href=3D"http://g3xb= m-qrp.blogspot.com/">http://g3xbm-qrp.blogspot.com/</a><br><a href=3D"http= ://www.g3xbm.co.uk">http://www.g3xbm.co.uk</a><br><a href=3D"http://www.yo= utube.com/user/g3xbm">http://www.youtube.com/user/g3xbm</a><br> G3XBM =A0 =A0GQRP 1678 =A0 =A0 =A0ISWL G11088<br> --0015174ff3528e21d004877b45a9--