Return-Path: Received: from mtain-dc10.r1000.mx.aol.com (mtain-dc10.r1000.mx.aol.com [172.29.64.138]) by air-db03.mail.aol.com (v127_r1.1) with ESMTP id MAILINDB034-86974b8eca0d1cc; Wed, 03 Mar 2010 15:43:57 -0500 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dc10.r1000.mx.aol.com (Internet Inbound) with ESMTP id 567ED380000A6; Wed, 3 Mar 2010 15:43:55 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1NmvOj-0008FW-SR for rs_out_1@blacksheep.org; Wed, 03 Mar 2010 20:42:25 +0000 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1NmvOj-0008FN-Ga for rsgb_lf_group@blacksheep.org; Wed, 03 Mar 2010 20:42:25 +0000 Received: from parrot.netcom.co.uk ([217.72.171.49]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1NmvOh-0001wV-CW for rsgb_lf_group@blacksheep.org; Wed, 03 Mar 2010 20:42:25 +0000 Received: from abelian.netcom.co.uk (i-194-106-52-83.freedom2surf.net [194.106.52.83]) by parrot.netcom.co.uk (Postfix) with ESMTP id D1C22227FA6 for ; Wed, 3 Mar 2010 20:39:59 +0000 (GMT) Received: from [127.0.0.1] (localhost [127.0.0.1]) by abelian.netcom.co.uk (8.13.1/8.13.1) with ESMTP id o23KgHEh026187 for ; Wed, 3 Mar 2010 20:42:17 GMT Message-ID: <4B8EC9A9.80507@abelian.org> Date: Wed, 03 Mar 2010 20:42:17 +0000 From: Paul Nicholson User-Agent: Thunderbird 2.0.0.14 (X11/20080421) MIME-Version: 1.0 To: rsgb_lf_group@blacksheep.org References: <4B8E8027.3060809@iup.uni-heidelberg.de> In-Reply-To: <4B8E8027.3060809@iup.uni-heidelberg.de> X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,NORMAL_HTTP_TO_IP=0.001 Subject: Re: LF: Re: 9kHz noise level Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: quoted-printable X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: *** X-Spam-Status: No, hits=3.0 required=5.0 tests=FROM_ENDS_IN_NUMS, NORMAL_HTTP_TO_IP,WEIRD_PORT 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: 3039ac1d408a4b8eca0b7d21 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) Can the tx frequency be confirmed? I've seen both 8.79 and 8.97 kHz mentioned in LF list messages and web pages. It looks like Horst St=F6cker is using 8.79kHz and Stefan Sch=E4fer is on 8.97kHz. Anyone else? The crucial factor is the level of natural VLF background noise after sferics have been removed. A couple of dB either way will make all the difference to detection. The noise is quite variable and can be significantly higher during geomagnetic or auroral activity, sometimes exhibiting strong bands of hiss. Generally it is stronger in summer than winter. At night the background increases. This is mostly due to a large number (10 or 20 per second) of weak sferics, too weak to reliably remove with simple amplitude threshold blanking. Check out the night time activity now on http://abelian.org/vlf/test.html This is typical night time activity level when the band is 'flat'. On the 13th I will try to recalibrate the rx at 9kHz so that the absolute background level can be displayed reliably. Range to Frankfurt here is about 840km. A long shot indeed! Slightly closer at 522km is a high quality receiver set up by Claudio Re I1RFQ and Renato Romero IK1QFK. It is located half way up a mountain in NW Italy, http://www.webalice.it/rromero/pnts_observatory.htm A live stream is here http://194.116.73.37:8000/pontese124.m3u This very clean stereo stream has E-field on the left and H-field on the right. --=20 Paul Nicholson