Return-Path: Received: (qmail 27707 invoked from network); 6 Mar 2003 17:32:29 -0000 Received: from netmail01.services.quay.plus.net (212.159.14.219) by mailstore with SMTP; 6 Mar 2003 17:32:29 -0000 Received: (qmail 89 invoked by uid 10001); 6 Mar 2003 17:32:29 -0000 Received: from post.thorcom.com (193.82.116.70) by netmail01.services.quay.plus.net with SMTP; 6 Mar 2003 17:32:28 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.12) id 18qzE3-0007JS-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 06 Mar 2003 17:32:11 +0000 Received: from [212.227.126.185] (helo=moutng.kundenserver.de) by post.thorcom.com with esmtp (Exim 4.12) id 18qzDy-0007JJ-00 for rsgb_lf_group@blacksheep.org; Thu, 06 Mar 2003 17:32:07 +0000 Received: from [212.227.126.206] (helo=mrelayng.kundenserver.de) by moutng.kundenserver.de with esmtp (Exim 3.35 #1) id 18qzDy-0005Us-00 for rsgb_lf_group@blacksheep.org; Thu, 06 Mar 2003 18:32:06 +0100 Received: from [62.158.74.111] (helo=W1KW) by mrelayng.kundenserver.de with asmtp (Exim 3.35 #1) id 18qzDx-0006iS-00 for rsgb_lf_group@blacksheep.org; Thu, 06 Mar 2003 18:32:05 +0100 Message-ID: <002001c2e406$441ea170$fe78a8c0@W1KW> From: "Holger 'Geri', DK8KW" To: rsgb_lf_group@blacksheep.org References: Date: Thu, 6 Mar 2003 18:31:05 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2720.3000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Subject: LF: Re: LF broadband QRN? Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=-13.5 required=5.0tests=ORIGINAL_MESSAGE,QUOTED_EMAIL_TEXT,QUOTE_TWICE_1,REFERENCESversion=2.50 X-Spam-Checker-Version: SpamAssassin 2.50 (1.173-2003-02-20-exp) X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false Hello John, in a computer-magazine saw a new kind of cable-less modems that work through the regular power line. No idea on which frequencies those devices operate, hopefully not on 73 or 136 kHz! Geri, DK8KW (W1KW) ----- Original Message ----- From: "John W Gould" To: "Rsgb_Lf_Group@Blacksheep.Org" Sent: Thursday, March 06, 2003 1:02 PM Subject: LF: LF broadband QRN? > > Since the 73kHz tests on Tuesday I have been monitoring at several times a > day and find a consistent and steady noise-level that is about 20dB below > the signal at 138.8kHz, and about 6dB below the one at 75kHz. Its a mains > type of buzz, beating at times with itself. Like most I have had this in > the past and put it down to RFI from switched-mode PSUs, however, it was > only sporadic in the past so I am wondering if it's something new. It seems > to be all the way up the LF band to just below the LW broadcast band (but > that cut-off could be a function of my aerial's resonance set at 73kHz). > > The only thoughts that I have is ADSL or signalling on the HV underground > cable somewhere beneath my garden. Certainly, ADSL will have become much > more used locally since I last did an serious listening on LF, but I would > have thought the radiation would be fairly low from the balanced overhead > telephone lines that are at least 200m from my aerial. I would have thought > that the shielding around underground HV mains cables would be sufficient to > stop low-level signaling causing problems. > > I can't see a real reason why TV related interfernce should increase near to > my home. How far away do TV's etc need to be before they cause problems, or > is it more caused by the interference conducting itself along the mains > cabling, etc. > > Any thoughts? > > 73 John, G3WKL > >