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[195.171.43.25]) by mx.google.com with ESMTP id l8si3002785wif.10.2014.03.16.07.12.44 for ; Sun, 16 Mar 2014 07:12:45 -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=@comcast.net Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1WPBIm-0007pZ-Sw for rs_out_1@blacksheep.org; Sun, 16 Mar 2014 13:40:32 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1WPBIm-0007pQ-5j for rsgb_lf_group@blacksheep.org; Sun, 16 Mar 2014 13:40:32 +0000 Received: from qmta10.emeryville.ca.mail.comcast.net ([76.96.30.17]) by relay1.thorcom.net with esmtp (Exim 4.82) (envelope-from ) id 1WPBIg-0005Qa-RD for rsgb_lf_group@blacksheep.org; Sun, 16 Mar 2014 13:40:31 +0000 Received: from omta11.emeryville.ca.mail.comcast.net ([76.96.30.36]) by qmta10.emeryville.ca.mail.comcast.net with comcast id eDfs1n0010mlR8UAADgQX0; Sun, 16 Mar 2014 13:40:24 +0000 Received: from Owner ([166.137.180.51]) by omta11.emeryville.ca.mail.comcast.net with comcast id eDg31n00E16w3ou8XDg9dX; Sun, 16 Mar 2014 13:40:19 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK From: "hvanesce" To: Date: Sun, 16 Mar 2014 06:39:57 -0700 Message-ID: <094701cf411d$421dcce0$c65966a0$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: Ac9BHQct5LC3IPLWTzqxpDT0ViHHTg== Content-Language: en-us DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1394977224; bh=XzoW2U76Ww+d75Mlk/z6rcLSRwY6ldChpRRQ3xp/kyE=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=keuMxEnNN4CYioAyfPbCmoqvF78gp6bvIbGbjCa5u/kz2ohHavNDxQzB7YkrmAl5b 8arAMwk2n0sZkqAp2xxx+rXfUMfMwsxUC7+54m2QgsNwjfMuzCaVLkfD7lX7aVi0f/ rlGH73rk5dwyxOiWIcJbiU1bBWveLlCCZp9eL6zb/I4BY0/ziOUyfXVSVGHxKXwXFh 1QiVe3COekxdh2f98jwH3liyK2z81gWAyb+cAA492bZSF09E09WSYpG1LUrlFaboKq JFP4TSpcPmvSZ/SLXU0gMBdb33B7UqdAImLjGFM8sCNtFDfZn2uL/JWY8KJrx4oCsP gYAYz16eUcG7g== 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: Markus, Thanks for the DHO diurnal plot. It's a memorable image, with interesting symmetries. [...] 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 [76.96.30.17 listed in list.dnswl.org] 0.0 FREEMAIL_FROM Sender email is commonly abused enduser mail provider (hvanesce[at]comcast.net) -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: 78d45eae26b8e09cb3b944588f353c28 Subject: LF: DHO Link Content-Type: multipart/alternative; boundary="----=_NextPart_000_0948_01CF40E2.95C117C0" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_40_50,HTML_MESSAGE 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 multipart message in MIME format. ------=_NextPart_000_0948_01CF40E2.95C117C0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Markus, Thanks for the DHO diurnal plot. It's a memorable image, with interesting symmetries. 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. 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) To make matters more interesting, Han (http://people.ee.duke.edu/~cummer/reprints/132_Han11_JGR_DaytimeDRegionShar pness.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. 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) 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. 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. * (D-region electron density sharpness) Regards, Jim ------=_NextPart_000_0948_01CF40E2.95C117C0 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Markus,

 

Thanks for the DHO diurnal plot.

 

It’s a memorable image, with interesting symmetries. =

 

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.

 

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)

 

To make matters more interesting, Han (http://people.ee.duke.edu/~cummer/reprints/132_Han11= _JGR_DaytimeDRegionSharpness.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.

 

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)

 

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. =

 

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.

 

  *  (D-region electron density = sharpness)

 

Regards,

 

Jim

 =

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