Return-Path: Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mi06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 4D180380000AB; Fri, 3 May 2013 15:30:46 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1UYLKJ-0001Fv-Db for rs_out_1@blacksheep.org; Fri, 03 May 2013 20:07:27 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1UYLKI-0001Fm-5m for rsgb_lf_group@blacksheep.org; Fri, 03 May 2013 20:07:26 +0100 Received: from nm2.bt.bullet.mail.ir2.yahoo.com ([212.82.98.153]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1UYLKF-0004mx-Km for rsgb_lf_group@blacksheep.org; Fri, 03 May 2013 20:07:25 +0100 Received: from [212.82.98.41] by nm2.bt.bullet.mail.ir2.yahoo.com with NNFMP; 03 May 2013 19:07:02 -0000 Received: from [46.228.39.185] by tm2.bt.bullet.mail.ir2.yahoo.com with NNFMP; 03 May 2013 19:07:02 -0000 Received: from [127.0.0.1] by smtp126.bt.mail.ir2.yahoo.com with NNFMP; 03 May 2013 19:07:02 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=s1024; t=1367608022; bh=zrfSSpacPoQH0bqwwKjsvSsYIIBWHCdYrCbS/L6QMo8=; h=X-Yahoo-Newman-Id:X-Yahoo-Newman-Property:X-YMail-OSG:X-Yahoo-SMTP:X-Rocket-Received:Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Priority:X-MSMail-Priority:X-Mailer:X-MimeOLE:X-Antivirus:X-Antivirus-Status; b=xpPbpoFCQLiFBA1xFGTOncB4Q46CuN9FrztR8ILSwWfyg5ETurNws0k2P+tuK0SN8SpyiqUT/QWrz/YHWU1mg67kXnbmf9WmtEZm0jZdRMwWmuP3TpoBRHMGSD0RFapZunTFdLSRynOVnx2H3oQyatpPEKNgOmxjMp7um+ekqgg= X-Yahoo-Newman-Id: 130566.82525.bm@smtp126.bt.mail.ir2.yahoo.com X-Yahoo-Newman-Property: ymail-3 X-YMail-OSG: dnTqSTYVM1m8zxboxiQdT8wJDYrsnKJ72xYRfNCV69PY543 VEq2cpTxOoOTgVtuhLT.cfMzHfWLg_3xcqEeAJH.ffK7RUDHEvzvHUS81oVf 6L1C_9uDd71zaco7qIqPpLwTY.oFCv6UuiUwx4jyAdegXYc66tujBUZ5hiwc SLQNJST5Az6ShpTeVeYIq_YgBT_B79xq.Kx7opfixASQ9LxMCOb7KTXrRle. Ka_GlCzM2tRBnCzFPp4gqDg7I1TyTXtDfvAOQ8Mw74E9ZNnWxHsBUN1JZ8cO f11Q3Yd3PiUC0jjIz3Dq5OgMz0LGP9utu60tEQA5SPTwmt5TAXo3nEH_J_dH 9WtoTkvz5CR3_.xStHH7mIA2tvvaAg8sM.KZUjLiftSlw8MVXCWpEO3mLXWy qg_ep6a9tFvUUicUDHIHwhkSV_ehkA4yT0t8oitKIBFJkRKMUYiUjjlqzKur yBk9kyYZQow-- X-Yahoo-SMTP: fpz.2VeswBBs59bVshRPmMN51lcO2lgFRIvE4XTqE8dRwOxd70E- X-Rocket-Received: from gnat (alan.melia@86.167.13.182 with login) by smtp126.bt.mail.ir2.yahoo.com with SMTP; 03 May 2013 19:07:01 +0000 UTC Message-ID: <6D09B821F62340A5B87877413E1FD4B6@gnat> From: "Alan Melia" To: References: <5182EB20.5000507@iup.uni-heidelberg.de> <73419E42F6C44E1EB1AB4FA0B2591817@SV8CSHP> <50100B1F0AB94D08B9E49C5DDB889EF3@White> Date: Fri, 3 May 2013 20:06:49 +0100 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-Antivirus: avast! (VPS 130503-0, 03/05/2013), Outbound message X-Antivirus-Status: Clean 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: Hi Markus the incident radiation has a wide band of wavelengths .....the reference is a QST article(Dec 1999) by Bob Brown NM7M (Dean of Physics at Berkley)I have a copy somewhere in a QST CD. Yes and incident in that was the "layer" irradiated from the top looks quite thick. Careful correlation of the times might support it. Here at about 1400km range the bottom of the dip in the morning from HGA is very close to the calculated groundwave strength. It is also very consistent suggesting it is not an out-phasing effect. [...] 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 [212.82.98.153 listed in list.dnswl.org] 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: a5eebf1400afcbaf7aee821a75970899 Subject: Re: LF: 136KHz propagation Content-Type: multipart/alternative; boundary="----=_NextPart_000_009B_01CE4839.BF379630" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: ** X-Spam-Status: No, hits=2.1 required=5.0 tests=FORGED_MUA_OUTLOOK,HTML_20_30, 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 x-aol-global-disposition: G X-AOL-SCOLL-AUTHENTICATION: mtain-mi06.r1000.mx.aol.com ; domain : btinternet.com DKIM : pass x-aol-sid: 3039ac1d7b8e518410655e09 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none This is a multi-part message in MIME format. ------=_NextPart_000_009B_01CE4839.BF379630 Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable Hi Markus the incident radiation has a wide band of wavelengths .....the = reference is a QST article(Dec 1999) by Bob Brown NM7M (Dean of Physics = at Berkley)I have a copy somewhere in a QST CD. Yes and incident in that = was the "layer" irradiated from the top looks quite thick. Careful = correlation of the times might support it. Here at about 1400km range = the bottom of the dip in the morning from HGA is very close to the = calculated groundwave strength. It is also very consistent suggesting it = is not an out-phasing effect.=20 I have just received an interesting book via Google ....one I can almost = understand :-)) so I will search further into this as I read it. The = book does cover the precipitation from the ring current and its effect = at LF This is the first time I have seen it in print......I dont have = the library access for expensive text-books I used to have when at work = :-(( All the previous papers described the effect but did not have the = satellite data to relate it to radio path loss. =20 ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Friday, May 03, 2013 6:14 PM Subject: Re: LF: 136KHz propagation Hi Alan,=20 the morning light shining from underneath is an intruiging notion, and = I've been wondering about it since you first mentioned it a while ago.=20 To me, one conceptual problem seems to be that the ultraviolet = radiation must have passed the same layer on the way down further east, = at the same slant angle. So far my understanding has been that = ionisation of different molecules selectively takes out certain = wavelengths. How can the D layer be transparent to a ray on the way = down, and then opaque on the way up? Best 73, Markus (DF6NM) From: Alan Melia=20 Sent: Friday, May 03, 2013 11:56 AM To: rsgb_lf_group@blacksheep.org=20 Subject: Re: LF: 136KHz propagation Hi Markus, Spiros, there is another interesting effect at dawn. The = weak rays of the rising sun actually strike the ionoshere first from = underneath !! this means that the first photodissociated ionisation is = very highly absorbing because it is formed at lower levels where the = pressure is higher and the electron mean-free-path is very short. This = has the effect of producing a deep dip in levels at dawn at mid-path. = That is dawn at an altitude of 50km or so, not ground level. This effect = is most noticable on N<>S paths which I think is the direction of the = grabbers from Spiros.=20 An hour or so later the Sun will have risen sufficiently to illuminate = the path from above and the daytime D-layer will build to provide = daytime skywave. The signal levels in daytime usually show a gentle = "dome" shape with the peak at mid-day at mid-path.=20 in the early days of 136kHz it was though that dawn would be a good = time for DX because the noise was lowest. However we eventually realised = that the noise was low because the distant noise which propagated by = skywave was wiped out at dawn by this effect. Thus the best DX times are = often (but not always :-)) ) early evening or about an hour before = dawn. Great Fun this Propagation stuff :-)) Alan G3NYK ----- Original Message ----- =20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Friday, May 03, 2013 8:36 AM Subject: Re: LF: 136KHz propagation Hi Spiros, not really strange: the rising sun is suddenly ionizing lower = ionospheric layers and increasing the absorption.=20 Here's a somewhat simplistic explanation of diurnal propagation: At = night, LF is mostly reflected by the lower boundary of the E-layer, at a = height of about 100 km. After sunrise, radiation starts to penetrate = deeper and ionize lower layers. So the conductivity of the D-layer = increases so much that it starts to first absorb, and later reflect, LF. = This is somewhat similar to a shunt resistor inserted in a = transmission line: During the night it's a large resistor which will let = most of the wave pass through, absorbing only a small fraction of the = power which depends on "conditions" (like DST index, describing charges = leaking down from a storage ring). At sunrise, the shunt suddenly = conducts more ("closer to 50 ohms") so most of the wave is being = absorbed. At midday when the sun is highest, the conductance is = approaching a "short circuit" which reflects the wave from a lower = altitude (about 80 km). After sunset, the electrons and ions in the lower layers recombine = quickly so the D-layer becomes transparent again. However at high = altitudes, the gas density is so low that charges take long to find a = partner, thus ionisation of the E and F layers persists throughout the = night.=20 Best 73, Markus (DF6NM) From: SV8CS- Spiros Chimarios=20 Sent: Friday, May 03, 2013 5:58 AM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: 136KHz propagation GM to all. The same strange propagation tonight as every night. At around 03.00z my signal disappear from DF6NM, DK7FC, YO/4X1RF & = G4WGT=20 grabbers. I have better prop earlier and during the day with day light. 73, Spiros SV8CS ------=_NextPart_000_009B_01CE4839.BF379630 Content-Type: text/html; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable
Hi Markus the incident radiation has a = wide band of=20 wavelengths .....the reference is a QST article(Dec 1999) by Bob = Brown NM7M=20 (Dean of Physics at Berkley)I have a copy somewhere in a QST CD. Yes and = incident in that was the "layer" irradiated from the top looks quite = thick.=20 Careful correlation of the times might support it. Here at about 1400km = range=20 the bottom of the dip in the morning from HGA is very close to the = calculated=20 groundwave strength. It is also very consistent suggesting it is not an=20 out-phasing effect. 
 
I have just received an interesting = book via Google=20 ....one I can almost understand :-)) so I will search further into this = as I=20 read it. The book does cover the precipitation from the ring current and = its=20 effect at LF This is the first time I have seen it in print......I dont = have the=20 library access for expensive text-books I used to have when at work=20 :-((   All the previous papers described the effect but did = not have=20 the satellite data to relate it to radio path = loss.  
----- Original Message -----
From:=20 Markus=20 Vester
Sent: Friday, May 03, 2013 6:14 = PM
Subject: Re: LF: 136KHz = propagation

Hi Alan,
 
the morning light shining from = underneath is an=20 intruiging notion, and I've been wondering about = it since you=20 first mentioned it a while ago. 
 
To me, one conceptual = problem seems to=20 be that the ultraviolet radiation must have passed = the=20 same layer on the way down further east, at the same slant angle. = So far=20 my understanding has been that ionisation of different molecules=20 selectively takes out certain wavelengths. How can the D layer be = transparent=20 to a ray on the way down, and then opaque on the way up?
 
Best 73,
Markus (DF6NM)

From: Alan Melia
Sent: Friday, May 03, 2013 11:56 AM
Subject: Re: LF: 136KHz propagation

Hi Markus, Spiros, there is another = interesting=20 effect at dawn. The weak rays of the rising sun actually strike the = ionoshere=20 first from underneath !! this means that the first = photodissociated=20 ionisation is very highly absorbing because it is formed at lower = levels where=20 the pressure is higher and the electron mean-free-path is very short. = This has=20 the effect of producing a deep dip in levels at dawn at mid-path. That = is dawn=20 at an altitude of 50km or so, not ground level. This effect is most = noticable=20 on N<>S paths which I think is the direction of the grabbers = from=20 Spiros.
 
An hour or so later the Sun will have = risen=20 sufficiently to illuminate the path from above and the daytime D-layer = will=20 build to provide daytime skywave. The signal levels in daytime usually = show a=20 gentle "dome" shape with the peak at mid-day at mid-path. =
 
in the early days of 136kHz it was = though that=20 dawn would be a good time for DX because the noise was lowest. However = we=20 eventually realised that the noise was low because the distant noise = which=20 propagated by skywave was wiped out at dawn by this effect. Thus the = best DX=20 times are often (but not always :-))   )  early evening = or=20 about an hour before dawn.
 
Great Fun this Propagation stuff=20 :-))
 
Alan G3NYK
----- Original Message -----  =
From:=20 Markus=20 Vester
To: rsgb_lf_group@blacksheep.org= =20
Sent: Friday, May 03, 2013 = 8:36=20 AM
Subject: Re: LF: 136KHz=20 propagation

Hi Spiros,
 
not really = strange: the rising=20 sun is suddenly ionizing lower ionospheric layers and = increasing=20 the absorption. 
 
Here's a somewhat simplistic = explanation of=20 diurnal propagation: At night, LF is mostly reflected by the lower = boundary=20 of the E-layer, at a height of about 100 km. After sunrise, = radiation starts=20 to penetrate deeper and ionize lower layers. So = the conductivity=20 of the D-layer increases so much that it starts to first absorb, and = later reflect, LF. 
 
This is somewhat similar to a shunt = resistor inserted in a transmission line: During the = night it's=20 a large resistor which will let most of the wave pass through,=20 absorbing only a small fraction of the power which depends on=20 "conditions" (like DST index, describing charges = leaking down from=20 a storage ring). At=20 sunrise, the shunt suddenly conducts = more ("closer to 50=20 ohms") so most of the wave is being absorbed. At midday when the sun = is=20 highest, the conductance is approaching a "short circuit" = which=20 reflects the wave from a lower altitude (about 80=20 km).
 
After sunset, the electrons and = ions in the=20 lower layers recombine quickly so the D-layer becomes transparent = again.=20 However at high altitudes, the gas density is so low=20 that charges take long to find a partner, thus ionisation = of the E=20 and F layers persists throughout the night. 
 
Best = 73,
Markus = (DF6NM)

Sent: Friday, May 03, 2013 5:58 AM
Subject: LF: 136KHz propagation

GM to all.
The same strange propagation tonight as = every=20 night.
At around 03.00z my signal disappear from DF6NM, DK7FC, = YO/4X1RF=20 & G4WGT
grabbers.
I have better prop earlier and during = the day=20 with day light.
73,=20 Spiros
SV8CS

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