Return-Path: Received: (qmail 5919 invoked from network); 6 Mar 2003 12:02:32 -0000 Received: from netmail02.services.quay.plus.net (212.159.14.221) by mailstore with SMTP; 6 Mar 2003 12:02:32 -0000 Received: (qmail 6169 invoked by uid 10001); 6 Mar 2003 12:02:32 -0000 Received: from post.thorcom.com (193.82.116.70) by netmail02.services.quay.plus.net with SMTP; 6 Mar 2003 12:02:32 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.12) id 18qu4K-0005x9-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 06 Mar 2003 12:01:48 +0000 Received: from [194.73.73.176] (helo=protactinium.btinternet.com) by post.thorcom.com with esmtp (Exim 4.12) id 18qu49-0005wq-00 for rsgb_lf_group@blacksheep.org; Thu, 06 Mar 2003 12:01:41 +0000 Received: from host213-122-43-157.in-addr.btopenworld.com ([213.122.43.157] helo=presario-1920) by protactinium.btinternet.com with smtp (Exim 3.22 #23) id 18qu45-0004Kf-00 for rsgb_lf_group@blacksheep.org; Thu, 06 Mar 2003 12:01:33 +0000 From: "John W Gould" To: "Rsgb_Lf_Group@Blacksheep.Org" Date: Thu, 6 Mar 2003 12:02:38 -0000 Message-ID: MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook IMO, Build 9.0.6604 (9.0.2911.0) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Importance: Normal Subject: LF: LF broadband QRN? Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=-5.7 required=5.0tests=MSGID_GOOD_EXCHANGEversion=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 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