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[195.171.43.25]) by mx.google.com with ESMTP id v8si3919335wiw.12.2014.03.16.16.42.45 for ; Sun, 16 Mar 2014 16:42:45 -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 1WPKED-0002q2-9i for rs_out_1@blacksheep.org; Sun, 16 Mar 2014 23:12:25 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1WPKEC-0002pt-CK for rsgb_lf_group@blacksheep.org; Sun, 16 Mar 2014 23:12:24 +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 1WPKE6-000815-C3 for rsgb_lf_group@blacksheep.org; Sun, 16 Mar 2014 23:12:23 +0000 Received: from omta07.emeryville.ca.mail.comcast.net ([76.96.30.59]) by qmta10.emeryville.ca.mail.comcast.net with comcast id ePAu1n0011GXsucAAPCGUF; Sun, 16 Mar 2014 23:12:16 +0000 Received: from Owner ([166.137.181.136]) by omta07.emeryville.ca.mail.comcast.net with comcast id ePBu1n00J2wyWjq8UPC0tT; Sun, 16 Mar 2014 23:12:11 +0000 X-DKIM-Result: Domain=comcast.net Result=Signature OK From: "hvanesce" To: References: <094701cf411d$421dcce0$c65966a0$@comcast.net> In-Reply-To: Date: Sun, 16 Mar 2014 16:11:47 -0700 Message-ID: <09a301cf416d$24fbb4b0$6ef31e10$@comcast.net> MIME-Version: 1.0 X-Mailer: Microsoft Outlook 14.0 Thread-Index: AQLeuqy07VvGx5kDmSUnI7yywyl9pQI8KKAJmLNuojA= Content-Language: en-us DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1395011536; bh=k2qxIqnI53ppFUlsjpHxdDccY4sXNhgvaDXAVzTkDyw=; h=Received:Received:From:To:Subject:Date:Message-ID:MIME-Version: Content-Type; b=TuswUZs2wOQzGJMraKlImg5EE6VedopF3zq2DPG4xhRM6AVO+qvdx6RKdtKrmIoMI tsVI5EmEb01i3AXdZCP1zJtNOzy4cc7T3go/vyiaoWWaue9JpGlKJXSRkv9wQ+CNAr yrSrv9s4oDtEvHbpjJ5JY32mivvenDEixas/c4fCDGz7z6fOmO0iE+3sl6NXq3M0zn V3eUE8yoXRv9LwJnlmieTCyxY2T+O3Ryvjj3ji+Z54tZpWWHkbSEk2AZjUzrLpdJHO cVThCrlU7WQP1NgTWvHIYZGQttni2/qvW48r9vYkb6AvqR+RDcEISgoBOTB6JB0iql /4qlVoiscHjfA== 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, From your message: "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 [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: 917bb99d4b5d86797eb255ea29aa077f Subject: LF: RE: Re: DHO Link Content-Type: multipart/alternative; boundary="----=_NextPart_000_09A4_01CF4132.789E8A60" 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_09A4_01CF4132.789E8A60 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Markus, >From your message: "Is this not just an electron density gradient, vertically measured?" Yes, as you concluded in a message that you sent later. "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." Likewise. The valuable data being generated seems to be ahead of tools. A simple modeler that could make qualitative (save quantitative for later) sense out of conspicuous fringe patterns, diurnals, and spatial sensitivities would be helpful. If a tool of that sort hinted at a path sensitivity that could be mitigated by (for example) a frequency change, or operation at an atypical time of day, it could save days of effort in some cases. I've started assembling a ray-based tool that is simple enough to accept different types of ionospheric and earth-surface parameters, and provide visibility into their effects. This could take a while, but the front end looks like it's working. "BTW Jim are you planning to start transmitting on VLF yourself, either 29.5 or below 9 kHz ?" I'm thinking of switching efforts to < 9 kHz. Work, travel and HW/SW issues have slowed my progress on 29.5 kHz (lots of almost-working 29.5 kHz equipment). On the other hand, my < 9 kHz TX and Rx have been operational for years, and I just need to install the recently-built pulse stretcher in line with the GPSDO, to operate at DX bandwidths (I'd been operating at > 1 mHz bandwidth without a GPSDO). I've been enjoying propagation analysis in the meantime, but running < 9kHz and 29.5 kHz concurrently would provide interesting propagation data and put the TX equipment to good use. 73, Jim AA5BW From: owner-rsgb_lf_group@blacksheep.org [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Markus Vester Sent: Sunday, March 16, 2014 10:05 AM To: rsgb_lf_group@blacksheep.org Subject: LF: Re: DHO Link 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? 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 ? Best 73, Markus (DF6NM) ----- Original Message ----- From: hvanesce To: rsgb_lf_group@blacksheep.org Sent: Sunday, March 16, 2014 2:39 PM Subject: LF: DHO Link 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_09A4_01CF4132.789E8A60 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Markus,

 

From your message:

 

“Is this not = just an electron density gradient, vertically = measured?”

Yes, as you concluded in a message that you sent later. =

 

“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…”

Likewise. The valuable data being generated seems to be ahead of = tools. A simple modeler that could make qualitative (save quantitative = for later) sense out of conspicuous fringe patterns, diurnals, and = spatial sensitivities would be helpful. If a tool of that sort hinted at = a path sensitivity that could be mitigated by (for example) a frequency = change, or operation at an atypical time of day, it could save days of = effort in some cases. I’ve started assembling a ray-based tool = that is simple enough to accept different types of ionospheric and = earth-surface parameters, and provide visibility into their effects. = This could take a while, but the front end looks like it’s = working.<= /span>

 

“BTW&nb= sp;Jim are you planning to start transmitting on VLF = yourself, either 29.5 or below 9 kHz = ?”

I’m thinking of switching efforts to < 9 kHz. Work, travel = and HW/SW issues have slowed my progress on 29.5 kHz (lots of = almost-working 29.5 kHz equipment). On the other hand, my < 9 kHz TX = and Rx have been operational for years, and I just need to install the = recently-built pulse stretcher in line with the GPSDO, to operate at DX = bandwidths (I’d been operating at > 1 mHz bandwidth without a = GPSDO).      

 

I’ve been enjoying propagation analysis in the meantime, but = running < 9kHz and 29.5 kHz concurrently would provide interesting = propagation data and put the TX equipment to good = use.

 

73,  Jim AA5BW

 

 

From:= = owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Markus = Vester
Sent: Sunday, March 16, 2014 10:05 AM
To: = rsgb_lf_group@blacksheep.org
Subject: LF: Re: DHO = Link

 

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? =

 

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 ? =  

 

Best = 73,

Markus = (DF6NM)

 

----- = Original Message -----

From:<= /b> hvanesce =

Sent:<= /b> = Sunday, March 16, 2014 2:39 PM

Subject: = LF: DHO Link

 

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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