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[195.171.43.25]) by mx.google.com with ESMTP id lr14si5238336wic.0.2014.03.16.10.31.03 for ; Sun, 16 Mar 2014 10:31:03 -0700 (PDT) Received-SPF: neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) client-ip=195.171.43.25; Authentication-Results: mx.google.com; spf=neutral (google.com: 195.171.43.25 is neither permitted nor denied by best guess record for domain of owner-rsgb_lf_group@blacksheep.org) smtp.mail=owner-rsgb_lf_group@blacksheep.org; dkim=fail header.i=@mx.aol.com Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1WPEV9-0001AN-St for rs_out_1@blacksheep.org; Sun, 16 Mar 2014 17:05:31 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1WPEV9-0001AE-7g for rsgb_lf_group@blacksheep.org; Sun, 16 Mar 2014 17:05:31 +0000 Received: from omr-d08.mx.aol.com ([205.188.109.207]) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.82) (envelope-from ) id 1WPEV5-0006bB-Ix for rsgb_lf_group@blacksheep.org; Sun, 16 Mar 2014 17:05:30 +0000 Received: from mtaout-mbe02.mx.aol.com (mtaout-mbe02.mx.aol.com [172.26.254.174]) by omr-d08.mx.aol.com (Outbound Mail Relay) with ESMTP id 50B3C700028FC for ; Sun, 16 Mar 2014 13:05:25 -0400 (EDT) Received: from Black (95-91-237-52-dynip.superkabel.de [95.91.237.52]) by mtaout-mbe02.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 223DF380000A9 for ; Sun, 16 Mar 2014 13:05:24 -0400 (EDT) Message-ID: From: "Markus Vester" To: References: <094701cf411d$421dcce0$c65966a0$@comcast.net> In-Reply-To: <094701cf411d$421dcce0$c65966a0$@comcast.net> Date: Sun, 16 Mar 2014 18:05:14 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6002.18197 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6002.18463 x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1394989525; bh=y/bAu/4egPsOzJF5XdeW7s8QyJB0ad1uN8v49y89KMg=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=BrAl2m+ZNefxdzXafcHaxmTJkKyPHyj0daJ8BTHHin+hPQ/FKxvGoWf12tM5qRXEn CqWHo7qdshGdmB/chHnEv0ycYA89rv7M0W6bh0EWi2liMdpQamUP73HD4p2jKxV3at WPlkO0kxRS39tpZHdvO5J91Xgy2UhLhuUA+qKTY0= x-aol-sid: 3039ac1afeae5325d9d468df X-AOL-IP: 95.91.237.52 X-Spam-Score: 0.0 (/) 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: Jim, thank you very much for pointing out the online papers. I'll take my time to read them, and (though being an engineer not a physicist) will at least try to conceive the main lines of thought. Not sure if I understand zenith angle dependence of the beta parameter - is this not just an electron density gradient, vertically measured? [...] Content analysis details: (0.0 points, 5.0 required) pts rule name description ---- ---------------------- -------------------------------------------------- -0.0 RCVD_IN_DNSWL_NONE RBL: Sender listed at http://www.dnswl.org/, no trust [205.188.109.207 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (markusvester[at]aol.com) -0.0 T_RP_MATCHES_RCVD Envelope sender domain matches handover relay domain -0.0 SPF_PASS SPF: sender matches SPF record 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: ceb2abb6ad60d8d61fe3b25552da2c0b Subject: LF: Re: DHO Link Content-Type: multipart/alternative; boundary="----=_NextPart_000_0016_01CF4142.47E2B300" 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 This is a multi-part message in MIME format. ------=_NextPart_000_0016_01CF4142.47E2B300 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Jim, thank you very much for pointing out the online papers. I'll take my = time to read them, and (though being an engineer not a physicist) will = at least try to conceive the main lines of thought. Not sure if I = understand zenith angle dependence of the beta parameter - is this not = just an electron density gradient, vertically measured?=20 I am also wondering how to make quantitative use of the long / short = path fringe patterns, which are so easily observed in spectrograms of = NWC 19.8 kHz in Europe. BTW Jim are you planning to start transmitting on VLF yourself, either = 29.5 or below 9 kHz ? =20 Best 73, Markus (DF6NM) ----- Original Message -----=20 From: hvanesce=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Sunday, March 16, 2014 2:39 PM Subject: LF: DHO Link Markus, =20 Thanks for the DHO diurnal plot. =20 It's a memorable image, with interesting symmetries.=20 =20 I remain hopeful of finding or making a model that qualitatively = represents VLF amplitude and phase diurnals for a substantial percentage = of cases. This would be very helpful in preparing for DX, QRP and other = activities. =20 Thomson has done some great work in this area (VLF diurnals). I was = surprised to find that he reverted (prior to 2011) to Wait's 2-parameter = ionospheric reflection model (using h and beta*, and adjusting them = empirically), instead of using LWPC or ModeFinder (which he mentions = require more knowledge of ionospheric parameters than is currently = available: = http://www.physics.otago.ac.nz/space/Thomson_LongPath_paper_JGR_2011.pdf = ; I thought Paul might also find this point interesting) =20 To make matters more interesting, Han = (http://people.ee.duke.edu/~cummer/reprints/132_Han11_JGR_DaytimeDRegionS= harpness.pdf ) recently showed considerable and substantial = disagreement (qualitative and quantitative) between beta* parameters = values derived (empirically) by a number of expert sources including = Thomson. Han's findings are well-summarized on the last page of his = paper. The kind of discrepancies shown by Han seem (to me) suggest a lot = of work remaining on the way to good diurnal amplitude and phase models. = Among the four expert sources on D-region beta cited by Han, there were = three different findings on the polarity of the change in beta with = zenith angle: decreasing beta with increasing zenith angle (1 of 4), = increasing beta with increasing zenith angle (2 of 4), relatively = constant beta with increasing zenith angle (1 of 4); not to mention = considerable disagreement between the four sources in magnitude of = sensitivity of beta to zenith angle. All of this is clearly summarized = on the last page of the paper. =20 I thought you might find the paragraph above interesting because it = shows a significant gap in the understanding of some basics that affect = (at some distances and on some days) whether VLF daytime signal strength = increases or decreases. In his conclusion, Han describes the magnitude = of disagreement in derived values for beta as surprising. He suggests = that the two-parameter model may not be sufficient (a circumstance that = Thomson hoped to avoid, see above) =20 On a related topic, Han's method of deriving beta (using broadband = signals) is interesting and appears to have substantial merit, but I'm = guessing that the available broadband sources used by Han (sferics) come = with their own issues in this type of measurement.=20 =20 I think I can end on a light note: if you have a chance to look at one = figure and one paragraph in this paper by Volland: = http://nvlpubs.nist.gov/nistpubs/jres/68D/jresv68Dn2p225_A1b.pdf , Adobe = Reader page 4 (document page 228), including Figure 3 and the paragraph = including "A remarkable exception from this rule has been observed in = Lindau (Germany), Figure 3 shows two successive daily phase variations = of GBR. Such phase inversions are rare.", I think you may find something = interesting, odd or even humorous.=20 =20 * (D-region electron density sharpness) =20 Regards, =20 Jim =20 ------=_NextPart_000_0016_01CF4142.47E2B300 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Jim,
 
thank you very much for pointing = out the=20 online papers. I'll take my time to read them, and (though being an = engineer not=20 a physicist) will at least try to conceive the main lines of thought. = Not sure=20 if I understand zenith angle dependence of the beta parameter = - is=20 this not just an electron density gradient, vertically measured?=20
 
I am also wondering how to make = quantitative=20 use of the long / short path fringe patterns, which are so=20 easily observed in spectrograms of NWC 19.8 kHz in=20 Europe.
 
BTW Jim are you planning = to start=20 transmitting on VLF yourself, either 29.5 or below 9 kHz ?=20  
 
Best 73,
Markus (DF6NM)
 
----- Original Message -----=20
From: hvanesce=20
Sent: Sunday, March 16, 2014 2:39 PM
Subject: LF: DHO Link

Markus,

 

Thanks=20 for the DHO diurnal plot.

 

It=92s=20 a memorable image, with interesting symmetries.

 

I=20 remain hopeful of finding or making a model that qualitatively = represents VLF=20 amplitude and phase diurnals for a substantial percentage of cases. This = would=20 be very helpful in preparing for DX, QRP and other=20 activities.

 

Thomson=20 has done some great work in this area (VLF diurnals). I was surprised to = find=20 that he reverted (prior to 2011) to Wait=92s 2-parameter ionospheric = reflection=20 model (using h and beta*, and adjusting them empirically), instead of = using LWPC=20 or ModeFinder (which he mentions require more knowledge of ionospheric=20 parameters than is currently available:  http://www.physics.otago.ac.nz/space/Thomson_LongPath_paper_JGR_= 2011.pdf=20 ; I thought Paul might also find this point = interesting)

 

To=20 make matters more interesting, Han (http://people.ee.duke.edu/~cummer/reprints/132_Han11= _JGR_DaytimeDRegionSharpness.pdf=20  ) recently showed considerable and substantial disagreement = (qualitative=20 and quantitative) between beta* parameters values derived (empirically) = by a=20 number of expert sources including Thomson. Han=92s findings are = well-summarized=20 on the last page of his paper. The kind of discrepancies shown by Han = seem (to=20 me) suggest a lot of work remaining on the way to good diurnal amplitude = and=20 phase models. Among the four expert sources on D-region beta cited by = Han, there=20 were three different findings on the polarity of the change in beta with = zenith=20 angle:  decreasing beta with increasing zenith angle (1 of 4), = increasing=20 beta with increasing zenith angle (2 of 4), relatively constant beta = with=20 increasing zenith angle (1 of 4); not to mention considerable = disagreement=20 between the four sources in magnitude of sensitivity of beta to zenith = angle.=20 All of this is clearly summarized on the last page of the=20 paper.

 

I=20 thought you might find the paragraph above interesting because it shows = a=20 significant gap in the understanding of some basics that affect (at some = distances and on some days) whether VLF daytime signal strength = increases or=20 decreases. In his conclusion, Han describes the magnitude of =  disagreement=20 in derived values for beta as surprising. He suggests that the = two-parameter=20 model may not be sufficient (a circumstance that Thomson hoped to avoid, = see=20 above)

 

On=20 a related topic, Han=92s method of deriving beta (using broadband = signals) is=20 interesting and appears to have substantial merit, but I=92m guessing = that the=20 available broadband sources used by Han (sferics) come with their own = issues in=20 this type of measurement.

 

I=20 think I can end on a light note: if you have a chance to look at one = figure and=20 one paragraph in this paper by Volland: http://nvlpubs.nist.gov/nistpubs/jres/68D/jresv68Dn2p225_A1b.pdf=20 , Adobe Reader page 4 (document page 228), including Figure 3 and the = paragraph=20 including =93A remarkable = exception from this=20 rule has been observed in Lindau (Germany), Figure 3 shows two = successive daily=20 phase variations of GBR=85 Such phase inversions are rare=85=94, = I=20 think you may find something interesting, odd or even = humorous.

 

 =20 *  (D-region electron density sharpness)

 

Regards,

 

Jim

 

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