Return-Path: Received: from mtain-di03.r1000.mx.aol.com (mtain-di03.r1000.mx.aol.com [172.29.64.7]) by air-mb01.mail.aol.com (v129.4) with ESMTP id MAILINMB014-a1884ca10731307; Mon, 27 Sep 2010 17:05:53 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-di03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 4F7D23800009C; Mon, 27 Sep 2010 17:05:52 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1P0KsE-0006T1-I1 for rs_out_1@blacksheep.org; Mon, 27 Sep 2010 22:04:34 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1P0Ks4-0006Sd-2u for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2010 22:04:24 +0100 Received: from relay.uni-heidelberg.de ([129.206.100.212]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1P0Ks4-0006Xf-0E for rsgb_lf_group@blacksheep.org; Mon, 27 Sep 2010 22:04:25 +0100 Received: from ix.urz.uni-heidelberg.de (cyrus-portal.urz.uni-heidelberg.de [129.206.100.176]) by relay.uni-heidelberg.de (8.14.1/8.14.1) with ESMTP id o8RL3opo019315 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Mon, 27 Sep 2010 23:03:50 +0200 Received: from extmail.urz.uni-heidelberg.de (extmail.urz.uni-heidelberg.de [129.206.100.140]) by ix.urz.uni-heidelberg.de (8.13.8/8.13.8) with ESMTP id o8RL4MH2024634 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Mon, 27 Sep 2010 23:04:22 +0200 Received: from [129.206.196.209] (vpn209a.rzuser.uni-heidelberg.de [129.206.196.209]) by extmail.urz.uni-heidelberg.de (8.13.4/8.13.1) with ESMTP id o8RL3lZ9001837 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO) for ; Mon, 27 Sep 2010 23:03:50 +0200 Message-ID: <4CA106D2.1090206@iup.uni-heidelberg.de> Date: Mon, 27 Sep 2010 23:04:18 +0200 From: =?ISO-8859-1?Q?Stefan_Sch=E4fer?= User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.1; de; rv:1.9.1.11) Gecko/20100711 Thunderbird/3.0.6 MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4CA0EB84.9010708@iup.uni-heidelberg.de> <741352.16197.qm@web111912.mail.gq1.yahoo.com> In-Reply-To: <741352.16197.qm@web111912.mail.gq1.yahoo.com> X-Spam-Score: 1.4 (+) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001,RATWARE_GECKO_BUILD=1.426 Subject: Re: VLF: Earth antenna DX on 8970 Hz confirmed Content-Type: multipart/alternative; boundary="------------080606070401040800020900" 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-sid: 3039ac1d40074ca1072f3324 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none X-Mailer: Unknown (No Version) --------------080606070401040800020900 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-MIME-Autoconverted: from 8bit to quoted-printable by relay.uni-heidelberg.de id o8RL3opo019315 Hi Daniele, I would assume it is independent of the distance. It is rather defined=20 by the type of noise, which means the Spherics here. But i am not an=20 expert on this. You can apply a test signal in SpecLab and use your own received noise.=20 Than you can adjust the filter settings and try to find the optimum S/N.= =20 Paul has written something about his trial and error tests to achieve=20 the best result. Maybe some further 1/10 dB can be achieved? 73, Stefan Am 27.09.2010 22:46, schrieb Daniele Tincani: > Hello Stefan, VLF, > in your knowledge, are Michael's settings for=20 > clipper/blanker valid regardless of the rx signal level or they need=20 > adjustment for farther stations? > Best regards > Daniele > > ------------------------------------------------------------------------ > *From:* Stefan Sch=E4fer > *To:* rsgb_lf_group@blacksheep.org > *Sent:* Mon, September 27, 2010 9:07:48 PM > *Subject:* VLF: Earth antenna DX on 8970 Hz confirmed > > VLF, > > Last saturday, *Michael Oexner* has successfully and *undoubtly=20 > received* *the message* i transmitted on the 600m spaced earth=20 > electrode antenna on *8970 Hz. *His RX antenna is a PA0RDT design.=20 > SpecLab was used to receive the signals. > > The applied TX power was about 250 W and the mode was DFCW-600. The=20 > antenna current was measured to be 530 mA. The QRN was reasonably low=20 > although it could have been better to transmit 2 hours before. > > There are 2 screenshots in one picture: The upper (in UTC) shows the=20 > result with a SpecLab internal band filter (BW=3D 6 kHz, centered=20 > arround 9 kHz). A clipping level of 6 dB was applied + the noise=20 > blanker set to 0.002/9/0.05. The lower (in UTC+2h) shows the same=20 > signal without using the internal SpecLab filter and without clipper,=20 > so just the blanker. You can see the difference! This means, as=20 > impressive demonstrated by Paul Nicholson on=20 > http://abelian.org/vlf/ss100801/, that bandfiltering is very important= =20 > on VLF. Mostly it means to exclude the mains hum and the strong MSK=20 > transmitters. A too narrow filter is not optimal since the blanker has= =20 > to "see" the QRN to blank it then. Thus i modified my VLF grabber=20 > circuit and have thrown out the 9 kHz band filter. > > After increasing the earth antennas efficiency soon, the signal should= =20 > be up to 10 dB stonger :-) > > 73, Stefan/DK7FC > > > --------------080606070401040800020900 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Hi Daniele,

I would assume it is independent of the distance. It is rather defined by the type of noise, which means the Spherics here. But i am not an expert on this.

You can apply a test signal in SpecLab and use your own received noise. Than you can adjust the filter settings and try to find the optimum S/N. Paul has written something about his trial and error tests to achieve the best result. Maybe some further 1/10 dB can be achieved?

73, Stefan

Am 27.09.2010 22:46, schrieb Daniele Tincani:
Hello Stefan, VLF,
 
in your knowledge, are Michael's settings for clipper/blanker valid regardless of the rx signal level or they need adjustment for farther stations?
 
Best regards
Daniele

From: Stefan Schäfer <schaefer@iup.uni-heidelberg.de>
To: rsgb_lf_group@blacksheep.org
Sent: Mon, September 27, 2010 9:07:48 PM
Subject: VLF: Earth antenna DX on 8970 Hz confirmed

VLF,

Last saturday, Michael Oexner has successfully and undoubtly received the message i transmitted on the 600m spaced earth electrode antenna on 8970 Hz. His RX antenna is a PA0RDT design. SpecLab was used to receive the signals.

The applied TX power was about 250 W and the mode was DFCW-600. The antenna current was measured to be 530 mA. The QRN was reasonably low although it could have been better to transmit 2 hours before.

There are 2 screenshots in one picture: The upper (in UTC) shows the result with a SpecLab internal band filter (BW= 6 kHz, centered arround 9 kHz). A clipping level of 6 dB was applied + the noise blanker set to 0.002/9/0.05. The lower (in UTC+2h) shows the same signal without using the internal SpecLab filter and without clipper, so just the blanker. You can see the difference! This means, as impressive demonstrated by Paul Nicholson on http://abelian.org/vlf/ss100801/, that bandfiltering is very important on VLF. Mostly it means to exclude the mains hum and the strong MSK transmitters. A too narrow filter is not optimal since the blanker has to "see" the QRN to blank it then. Thus i modified my VLF grabber circuit and have thrown out the 9 kHz band filter.

After increasing the earth antennas efficiency soon, the signal should be up to 10 dB stonger :-)

73, Stefan/DK7FC



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