Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mk01.r1000.mx.aol.com (Internet Inbound) with ESMTP id 3077338004D75 for ; Sat, 23 Mar 2013 15:24:16 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UJSxr-0004ZN-4s for rs_out_1@blacksheep.org; Sat, 23 Mar 2013 18:14:47 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UJSxq-0004ZE-BG for rsgb_lf_group@blacksheep.org; Sat, 23 Mar 2013 18:14:46 +0000 Received: from imr-db02.mx.aol.com ([205.188.91.96]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1UJSxm-0005F4-6d for rsgb_lf_group@blacksheep.org; Sat, 23 Mar 2013 18:14:45 +0000 Received: from mtaout-mb05.r1000.mx.aol.com (mtaout-mb05.r1000.mx.aol.com [172.29.41.69]) by imr-db02.mx.aol.com (Outbound Mail Relay) with ESMTP id 1B2E41C000131 for ; Sat, 23 Mar 2013 14:14:19 -0400 (EDT) Received: from White (188-195-246-26-dynip.superkabel.de [188.195.246.26]) by mtaout-mb05.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 0B637E0000CD for ; Sat, 23 Mar 2013 14:14:15 -0400 (EDT) Message-ID: From: "Markus Vester" To: References: <919c99d265d841f49e869c4353463502@kabelmail.de> <202E6627EAE640DEB0DA451BC1FE80BF@White> <6FB3AB75CA3B487EAE3C64A01C80EAC5@AGB> Date: Sat, 23 Mar 2013 19:14:10 +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=20121107; t=1364062459; bh=BIo7l0I3nsV+urTGz7v9o8H/58RjHNZOA3gU1K6n3f8=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=Gpn62qQ2Glrua1B8cDE08rgXaHr67wtoYU7LhXhcVhX0g+EdiP6Eczbw9VQg5nIpF 34IxWvkziinWu0ri30JDnMrgKrxJrr2nIHEjU5IJR8t1dfJahRVzhHbvC/lruJ/Xmy gphfht+hp6KUW96K6cvGjaMaOmsRlzLvcjDQa/JY= X-AOL-SCOLL-SCORE: 0:2:390822208:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-Spam-Score: -2.5 (--) 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 Graham, yes this is an interesting option. The correlation detector looks for spectral peaks in a long narrow FFT, which integrates across the total duration of the Opera sequence (about 2000s for Op 32). For a reliable detection, a phase-coherent central peak needs to be at about 15 dB SNR in the corresponding bin width (0.5 mHz). Taking a 100% duty cycle carrier for reference, at 50% duty cycle we have 25% (-6 dB) energy in the central peak, and another 25% in both AM sidebands together. Thus for Op-32, the threshold is around 21 dB carrier-SNR in 0.5 mHz, scaling to -46 dB in 2.5 kHz (or -50 "dBOp" on the Opera scale). The modulation energy will ideally also bring up a 15 dB correlation peak, which is normally sufficient to ensure unambiguous callsign identification. Extending the duration from 32 minutes to ~ 4 hours would gain another 9 dB, arriving at a threshold of -55 dB in 2.5 kHz (-59 dBOp). [...] Content analysis details: (-2.5 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [205.188.91.96 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 -2.5 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 X-Scan-Signature: 719233b489c0727505743c30ad56ff81 Subject: Re: LF: DJ8WX 8.97 kHz Content-Type: multipart/alternative; boundary="----=_NextPart_000_0012_01CE27FA.9946BBE0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.7 required=5.0 tests=HTML_40_50, HTML_FONTCOLOR_UNSAFE,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-mk01.r1000.mx.aol.com ; domain : mx.aol.com DKIM : pass x-aol-sid: 3039ac1d6185514e015d7310 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : temperror Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_0012_01CE27FA.9946BBE0 Content-Type: text/plain; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable Hi Graham, yes this is an interesting option. The correlation detector looks for spectral peaks in a long narrow FFT, = which integrates across the total duration of the Opera sequence (about = 2000s for Op 32). For a reliable detection, a phase-coherent central = peak needs to be at about 15 dB SNR in the corresponding bin width (0.5 = mHz). Taking a 100% duty cycle carrier for reference, at 50% duty cycle = we have 25% (-6 dB) energy in the central peak, and another 25% in both = AM sidebands together. Thus for Op-32, the threshold is around 21 dB = carrier-SNR in 0.5 mHz, scaling to -46 dB in 2.5 kHz (or -50 "dBOp" on = the Opera scale). The modulation energy will ideally also bring up a 15 = dB correlation peak, which is normally sufficient to ensure unambiguous = callsign identification. Extending the duration from 32 minutes to ~ 4 = hours would gain another 9 dB, arriving at a threshold of -55 dB in 2.5 = kHz (-59 dBOp). On my rather noisy VLF grabber, the carrier from DJ8WX reached about 9 = dB SNR today. Scaling the bandwidth from 1.5*0.48 mHz to 2.5 kHz, we get = -56.5 dB SNR (or -60.5 dBOp) - just 1.5 dB bit short of an Op-4H = detection. Of course other online VLF receivers (namely Paul Nicholson = and OK2BVG) do have significantly better receive conditions so Op-4H = correlation should be quite feasible there. For the standard Opera software decoder, Rik's measurements had = indicated a decoding threshold of -23 dB in 2.5 kHz for two-minute = Opera-2. This scales to -35 dB for Op-32 and -44 dB for Op-4H (-39 and = -48 dBOp respectively). Thus for Op-4H you'd want to see a carrier SNR = of 21.5 dB in a "qrss 6000" grabber window, which seems a fair challenge = at the distances we're interested in. For comparison, Stefan's famous LF reception at VK2DDI showed about 15 = dB SNR in an 11 mHz spectrogram, equivalent to -37 dB in 2.5 kHz (-41 = dBOp). Thus an "easy target" for Op-32 or even Op-8 correlation, but = still slightly below the edge of the classic Op-32 decoder. Best 73, Markus (DF6NM) From: Graham=20 Sent: Saturday, March 23, 2013 1:39 PM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: DJ8WX 8.97 kHz Marcu's / Uwe This would make a good test for the Op4H ( 4 hour) mode and = the correlation detector ? To date there have been no 'dx' test , with the addition of the = correlation ,then that should give three possible detections ? OP4H decode , qrss plot and Correlation ( and 50% saving on = power hihi)=20 OP4H has AFC as the shorter modes and is designed for normal sound = card use. with sound-card audio or CW-comport Tx keying , rx audio = is direct in from sound card , in short range tests -50 db s/n = has been reached , but that is a data decode , would the correlation = , take the level below the qrss plot ? 73-Graham G0NBD From: Markus Vester=20 Sent: Saturday, March 23, 2013 12:15 PM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: DJ8WX 8.97 kHz Hi Uwe, your 8970 Hz signal is widely visible across Europe http://abelian.org/vlf/fbins.shtml#p=3D1364032800&b=3D070&s=3Dsp http://www.qsl.net/pa1sdb/ http://www.ok2bvg.cz/vlfgrabber/ http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html http://dl.dropbox.com/u/23312120/vlfgrabber.html and now also good traces here http://www.mydarc.de/df6nm/vlf/vlfgrabber.htm Best 73, Markus (DF6NM) ------=_NextPart_000_0012_01CE27FA.9946BBE0 Content-Type: text/html; charset="Windows-1252" Content-Transfer-Encoding: quoted-printable
Hi Graham,
 
yes this is an interesting = option.
 
The correlation detector looks for = spectral=20 peaks in a long narrow FFT, which integrates across = the total=20 duration of the Opera sequence (about 2000s for Op 32). For a = reliable=20 detection, a phase-coherent central peak needs to be at = about 15=20 dB SNR in the corresponding bin width (0.5 mHz). Taking a 100% duty = cycle=20 carrier for reference, at 50% duty cycle we have 25% (-6 dB)=20 energy in the central peak, and another 25% in both AM sidebands = together.=20 Thus for Op-32, = the threshold is around=20 21 dB carrier-SNR in 0.5 mHz, scaling to -46 dB in 2.5 kHz (or -50 = "dBOp" on the=20 Opera scale). The modulation energy will ideally also bring up a 15 = dB=20 correlation peak, which is normally sufficient = to ensure unambiguous=20 callsign identification. Extending = the=20 duration from 32 minutes to ~ 4 hours would gain another 9=20 dB, arriving at a threshold of -55 dB in 2.5 kHz (-59=20 dBOp).
 
On my rather noisy VLF grabber, the carrier from = DJ8WX reached=20 about 9 dB SNR today. Scaling the bandwidth from 1.5*0.48 mHz = to 2.5=20 kHz, we get -56.5 dB SNR (or -60.5 dBOp) - just 1.5 = dB bit=20 short of an Op-4H detection. Of course other online VLF receivers = (namely=20 Paul Nicholson and OK2BVG) do have significantly better receive = conditions=20 so Op-4H correlation should be quite feasible there.
 
For the standard Opera software = decoder, Rik's=20 measurements had indicated a decoding threshold of -23 dB in 2.5 kHz for = two-minute Opera-2. This scales to -35 dB for Op-32 and -44 dB = for=20 Op-4H (-39 and -48 dBOp respectively). Thus for Op-4H=20 you'd want to see a carrier SNR of 21.5 dB in a "qrss = 6000"=20 grabber window, which seems a fair challenge at the distances we're = interested=20 in.
 
For comparison, Stefan's famous LF reception at VK2DDI showed about = 15 dB=20 SNR in an 11 mHz spectrogram, equivalent to -37 dB in 2.5 kHz = (-41=20 dBOp). Thus an "easy target" for Op-32 or even Op-8 correlation, = but still=20 slightly below the edge of the classic Op-32 decoder.
 
Best 73,
Markus (DF6NM)
 
From: Graham
Sent: Saturday, March 23, 2013 1:39 PM
Subject: Re: LF: DJ8WX 8.97 kHz

Marcu's / Uwe
 
This would  make a  good  test  for = the  =20 Op4H  ( 4 hour)  mode  and  the =20 correlation   detector ?
 
To date  there  have been  no  'dx' test , with = the  addition  of  the  correlation  = ,then =20 that  should give  three   possible detections  = ?
 
OP4H decode ,  qrss plot  and =  Correlation   =20 ( and  50%  saving on power hihi)
 
OP4H has AFC  as the  shorter  modes and  = is =20 designed for  normal sound card  use. with  = sound-card =20 audio or  CW-comport Tx keying , rx  audio is  = direct  in=20 from  sound  card  , in short range  tests  -50 = db=20 s/n  has been reached , but  that  is a data  decode = , would=20 the  correlation , take the  level  below the  = qrss =20 plot ?
 
73-Graham
G0NBD
 
 
 

From: Markus Vester
Sent: Saturday, March 23, 2013 12:15 PM
To: rsgb_lf_group@blacksheep.org= =20
Subject: LF: DJ8WX 8.97 kHz

Hi=20 Uwe,
 
your 8970=20 Hz signal is widely visible across = Europe
 
http://abelian.org/vlf/fbins.shtml#p=3D1364032800&b=3D070&am= p;s=3Dsp
http://www.qsl.net/pa1sdb/=
http://www.ok2bvg.cz/vlfgrabber= /
http://www.iup.uni-heidelberg.de/schaefer_vlf/DK7FC_VLF_Grabber.html=
http://dl.dropb= ox.com/u/23312120/vlfgrabber.html
 
and now also good traces = here
http://www.mydarc.= de/df6nm/vlf/vlfgrabber.htm
 
Best = 73,
Markus = (DF6NM)
 
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