Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mg04.r1000.mx.aol.com (Internet Inbound) with ESMTP id 8BF83380000C7; Tue, 27 Nov 2012 17:07:08 -0500 (EST) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1TdTI5-0007Yb-UB for rs_out_1@blacksheep.org; Tue, 27 Nov 2012 22:06:05 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1TdTI5-0007YS-8T for rsgb_lf_group@blacksheep.org; Tue, 27 Nov 2012 22:06:05 +0000 Received: from imr-mb02.mx.aol.com ([64.12.207.163]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1TdTI1-0008Ls-Sk for rsgb_lf_group@blacksheep.org; Tue, 27 Nov 2012 22:06:04 +0000 Received: from mtaout-da02.r1000.mx.aol.com (mtaout-da02.r1000.mx.aol.com [172.29.51.130]) by imr-mb02.mx.aol.com (Outbound Mail Relay) with ESMTP id 99F2D380000ED for ; Tue, 27 Nov 2012 17:05:39 -0500 (EST) Received: from White (nrbg-4dbf0050.pool.mediaWays.net [77.191.0.80]) by mtaout-da02.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 01378E00008E for ; Tue, 27 Nov 2012 17:05:35 -0500 (EST) Message-ID: <83FF3173906841FAB4E13EA1E4FB1AB1@White> From: "Markus Vester" To: References: <8CDDC896504242CB8DDE22806560D8EF@GaryAsus> Date: Tue, 27 Nov 2012 23:05:35 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal Importance: Normal X-Mailer: Microsoft Windows Live Mail 12.0.1606 X-MIMEOLE: Produced By Microsoft MimeOLE V12.0.1606 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20110426; t=1354053939; bh=EBFP+P17+a8DQL5IFzatWWe8N7FMQN0KdehJm+x7EJs=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=BK/bkbHbmZWMSLe2M0uElaDPItSw56JZzShWeLVd1ez1MOwnL2P5D1ONwjssK9WyD KKDUn2SZJkQSmQ2yWo6PXi2lAstYua8d87qKuDxtADnstPKG14Z92edDCol/tDlfDH zpEAgBaM7RcXOG1jKhYunOvOf2VieIzwfaWduIyk= X-AOL-SCOLL-SCORE: 0:2:454299264:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-Spam-Score: 0.6 (/) X-Spam-Report: Spam detection software, running on the system "relay1.thorcom.net", has identified this incoming email as possible spam. The original message has been attached to this so you can view it (if it isn't spam) or label similar future email. If you have any questions, see the administrator of that system for details. Content preview: Hi Gary, the wideband screenshot (HDSDR Waterfall) shows the typical signature of a switchmode power supply. Most choppers run at lower frequency (eg 45 kHz), with the harmonic corrupting the LF band. The carrier is FM-modulated by the 100 Hz ripple of he primary voltage and usually swept across several kHz (which ironically is said to help passing EMC tests). The banded structure is due to the beating between the upward and downward chirps, a maximum occurs when the lag between the two is such that they are in phase. Near the edges of the spectrum, the bands are often wider because the two passes are closer in time near the point of return. [...] Content analysis details: (0.6 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [64.12.207.163 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) -0.0 SPF_PASS SPF: sender matches SPF record -0.4 RP_MATCHES_RCVD Envelope sender domain matches handover relay domain 0.0 HTML_MESSAGE BODY: HTML included in message 0.0 T_DKIM_INVALID DKIM-Signature header exists but is not valid 1.0 FREEMAIL_REPLY From and body contain different freemails X-Scan-Signature: e2b7e65dcf7cf6551ab81105a525fe0f Subject: Re: LF: LF interference Content-Type: multipart/alternative; boundary="----=_NextPart_000_0015_01CDCCF3.B54BB7D0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_40_50,HTML_MESSAGE, MISSING_OUTLOOK_NAME 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-SCOLL-AUTHENTICATION: mtain-mg04.r1000.mx.aol.com ; domain : mx.aol.com DKIM : pass x-aol-sid: 3039ac1d60cc50b5398b2f31 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_0015_01CDCCF3.B54BB7D0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Gary, the wideband screenshot (HDSDR Waterfall) shows the typical signature of = a switchmode power supply. Most choppers run at lower frequency (eg 45 = kHz), with the harmonic corrupting the LF band. The carrier is = FM-modulated by the 100 Hz ripple of he primary voltage and usually = swept across several kHz (which ironically is said to help passing EMC = tests). The banded structure is due to the beating between the upward = and downward chirps, a maximum occurs when the lag between the two is = such that they are in phase. Near the edges of the spectrum, the bands = are often wider because the two passes are closer in time near the point = of return.=20 The other spectrogram (137700...2130) looked a bit weird at first. But = it can be explained by the NB periodically triggering on the hash, twice = per 10 ms. This apparently creates 200 Hz aliases of the DCF39 signal, = which are visible as discrete lines on 138830 - N x 200 Hz. Of course = these lines also carry an image of the DCF modulation telegrams. Try to observe whether on and off times are correlated to neighbours' = christmas light effects (these often radiate badly due to long and = outdoor wiring). Or walk around and try to locate it with a portable LF = receiver in AM mode, preferably one with a small telescopic E-field = antenna. A couple of years back I have made an attempt on a software hash = canceller, which estimates the repeating pattern of the chirps and tries = to subtract it. If you would like to experiment with this, it's at http://df6nm.bplaced.net/smps_nc/smps_nc.zip (114 kB) Best 73, Markus (DF6NM) From: Gary - G4WGT=20 Sent: Tuesday, November 27, 2012 9:41 PM To: LF Group ; rsgb_lf_group@yahoogroups.co.uk=20 Subject: LF: LF interference Hi All, For about 7 days or so I have been getting some very strong interference = on the 136kHz band. At first it only came on for short periods (up to 1 = or 2 hours) but from yesterday it came on early evening & stayed until = early today & is there again tonight. The interfering signal sounds like a buzzing noise on my LF Rx & the = visual display shows a very unstable form. It starts from about = 137.000kHz upwards & fades towards 145kHz. I have placed 3 captures on Dropbox, 2 SpecLab (showing the start time) = & 1 HDSDR showing the extent of the interference. https://www.dropbox.com/s/fhx3daelhpf9mn5/137700Hz-1211262130.jpg https://www.dropbox.com/s/ip7s3gdnn8uyned/137700Hz-1211271830.jpg https://www.dropbox.com/s/r51adwp0avx75x0/HDSDR%20Waterfall.jpg If anyone can identify this type of interference I would be pleased for = comments. I believe I have eliminated all my own gear & household items. Thanks & 73, Gary - G4WGT. ------=_NextPart_000_0015_01CDCCF3.B54BB7D0 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Gary,
 
the wideband screenshot (HDSDR = Waterfall)=20 shows the typical signature of a switchmode power supply. Most choppers = run at=20 lower frequency (eg 45 kHz), with the harmonic corrupting = the LF=20 band. The carrier is FM-modulated by the 100 Hz ripple of he = primary=20 voltage and usually swept across several kHz (which ironically is = said to=20 help passing EMC tests). The banded structure is due to the beating = between the upward and downward chirps, a maximum occurs when the = lag=20 between the two is such that they are in phase. Near the edges = of the=20 spectrum, the bands are often wider because the two passes are closer in = time=20 near the point of return.
 
The other spectrogram (137700...2130) looked a bit weird at first. = But it=20 can be explained by the NB periodically triggering on the hash, twice = per 10 ms.=20 This apparently creates 200 Hz aliases of the DCF39 = signal, which are=20 visible as discrete lines on 138830 - N x 200 Hz. Of = course=20 these lines also carry an image of  the DCF modulation=20 telegrams.
 
Try to observe whether on and off times are correlated to = neighbours' christmas light effects (these often radiate badly due = to long=20 and outdoor wiring). Or walk around and try to locate it with a portable = LF=20 receiver in AM mode, preferably one with a small telescopic = E-field=20 antenna.
 
A couple of years back I have made an attempt on a software = hash=20 canceller, which estimates the repeating pattern of the chirps and tries = to=20 subtract it. If you would like to experiment with this, it's at
http://df6nm.bplace= d.net/smps_nc/smps_nc.zip (114=20 kB)
 
Best 73,
Markus (DF6NM)
 
 

From: Gary - G4WGT
Sent: Tuesday, November 27, 2012 9:41 PM
To: LF Group ; rsgb_lf_group@yahoogroups= .co.uk=20
Subject: LF: LF interference

Hi All,
 
For about 7 days or so I have been = getting some=20 very strong interference on the 136kHz band. At first it only came on = for short=20 periods (up to 1 or 2 hours) but from yesterday it came on early = evening=20 & stayed until early today & is there again = tonight.
 
The interfering signal sounds like a = buzzing noise=20 on my LF Rx & the visual display shows a very unstable form. It = starts from=20 about 137.000kHz upwards & fades towards 145kHz.
 
I have placed 3 captures on Dropbox, 2 = SpecLab=20 (showing the start time) & 1 HDSDR showing the extent of the=20 interference.
 
https://www.dropbox.com/s/fhx3daelhpf9mn5/137700Hz-1211262130.jpg
https://www.dropbox.com/s/ip7s3gdnn8uyned/137700Hz-1211271830.jpg
= https://www.dropbox.com/s/r51adwp0avx75x0/HDSDR%20Waterfall.jpg
 
If anyone can identify this type of = interference I=20 would be pleased for comments. I believe I have eliminated all my own = gear &=20 household items.
 
Thanks & 73,
 
Gary - G4WGT.
 
 
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