Delivered-To: daveyxm@virginmedia.com Received: by 10.50.96.198 with SMTP id du6csp120899igb; Sun, 3 Nov 2013 16:02:02 -0800 (PST) X-Received: by 10.14.212.72 with SMTP id x48mr15400007eeo.0.1383523322052; Sun, 03 Nov 2013 16:02:02 -0800 (PST) Return-Path: Received: from post.thorcom.com (post.thorcom.com. [195.171.43.25]) by mx.google.com with ESMTP id l4si8613703eew.11.2013.11.03.16.02.01 for ; Sun, 03 Nov 2013 16:02:02 -0800 (PST) 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=pass header.i=@mx.aol.com Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Vd7aw-0004If-I8 for rs_out_1@blacksheep.org; Mon, 04 Nov 2013 00:00:38 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Vd7av-0004IW-PM for rsgb_lf_group@blacksheep.org; Mon, 04 Nov 2013 00:00:37 +0000 Received: from omr-m04.mx.aol.com ([64.12.143.78]) by relay1.thorcom.net with esmtps (TLSv1:AES256-SHA:256) (Exim 4.77) (envelope-from ) id 1Vd7as-00030U-PN for rsgb_lf_group@blacksheep.org; Mon, 04 Nov 2013 00:00:36 +0000 Received: from mtaout-db02.r1000.mx.aol.com (mtaout-db02.r1000.mx.aol.com [172.29.51.194]) by omr-m04.mx.aol.com (Outbound Mail Relay) with ESMTP id A910A700000AE for ; Sun, 3 Nov 2013 19:00:31 -0500 (EST) Received: from White (95-91-237-85-dynip.superkabel.de [95.91.237.85]) by mtaout-db02.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 23CD3E0000AC for ; Sun, 3 Nov 2013 19:00:28 -0500 (EST) Message-ID: <02CA06069FC74FEAAEF85930320E0E34@White> From: "Markus Vester" To: References: <05b201ced8d7$24e85fe0$6eb91fa0$@comcast.net> <2FA25F9F5AB648A98C2F0C7A96F0D1B2@gnat> Date: Mon, 4 Nov 2013 01:00:25 +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 x-aol-global-disposition: G DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mx.aol.com; s=20121107; t=1383523231; bh=iS32pp0sr5qGKzCMldoIvBVP1Xv1GFCzZOKzdb8KnIs=; h=From:To:Subject:Message-ID:Date:MIME-Version:Content-Type; b=hCG82O7A04dzgNl5qx44/YGRL/p7fsesdQkUHhKH2FnucH+uMRrFw/IlpRvdMmVM4 TttK2wsNLNXRsqxmN1wZp2bvVxWhfB0KNHedMz6iwIvuwrbaGf01SWPwLlO8MnPudQ e3nR9VGCccl12tlBkIE4qJ5Bzlav134/gkgc1wQ4= x-aol-sid: 3039ac1d33c25276e39b3ecf X-AOL-IP: 95.91.237.85 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: Alan, based on Loran-C measurements, I would agree on the ballpark figure of -6 dB per hop. Not sure though if land reflections are really so much worse than seawater, as for low angle incidence the reflection coefficient may still be close to unity. [...] 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 [64.12.143.78 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 -0.0 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: 31e464b680e3427073f16da582bb11f1 Subject: Re: LF: Re: RE: Hartmut's Grabber On Last Night... Content-Type: multipart/alternative; boundary="----=_NextPart_000_0004_01CED8F9.3F50F690" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.3 required=5.0 tests=HTML_50_60,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 Status: O X-Status: X-Keywords: X-UID: 2879 Dies ist eine mehrteilige Nachricht im MIME-Format. ------=_NextPart_000_0004_01CED8F9.3F50F690 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Alan, based on Loran-C measurements, I would agree on the ballpark figure of = -6 dB per hop. Not sure though if land reflections are really so much = worse than seawater, as for low angle incidence the reflection = coefficient may still be close to unity. > A 16dB fade suggests 20dB or so difference in amplitude. No. -20 dB =3D 0.1 x amplitude for the weaker signal. But 1+-0.1 =3D = 1.1...0.9, which would be a very flat fade (1.74 dB max to min). To = produce deep fades, the signals would need to be rather similar in = magnitude. 73,=20 Markus (DF6NM) From: Alan Melia=20 Sent: Monday, November 04, 2013 12:40 AM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: Re: RE: Hartmut's Grabber On Last Night... Hi Jim yes I think it is a phase effect, the reinforcement/cancellation = is probably between 2 hop and 3 hop paths. A 16dB fade suggests 20dB or = so difference in amplitude. I used to reckon on about a 12dB per = ionospheric hop and less, maybe 6dB, for a sea "bounce" based on signal = from Joe VO1NA and the Naval station at Newport Corner near Halifax NS. = Each hop has a maximum range of about 2000km. There are several effects = around the sunset shadow area that could add to the effect too. Higher = angles at the ionosphere may penetrate futher before returning giving = higher attenuation to the higher hop modes.=20 A thumbnail calculation suggests hop3 ampltude of about -23dB below hop = 2 would give a 17dB fade as it goes in and out of phase. Very much a "hand waving" estimate but a useful empirical guide. Alan G3NYK ----- Original Message -----=20 From: hvanesce=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Sunday, November 03, 2013 8:56 PM Subject: LF: RE: Hartmut's Grabber On Last Night... Bob, =20 This is the third time that I've noticed Dex's signal peaking = substantially (>15dB?) starting around 0500, at approximately the same = time that your signal begins a substantial fade. I've seen this twice on = captures from Hartmut's grabber, and once on a capture from Mike's = grabber.=20 =20 An interesting example is 21 October 2013, when captures by Henny, = Mike and Hartmut all showed a fade of roughly 10-15dB in your signal = from 0500-0530, with Mike's grabber (which showed Dex's signal clearly = around that time) showing a rise in Dex's signal of roughly 10-15dB. =20 =20 I wonder if this could be attributable to modal phase = reinforcement/cancellation near the terminator? The relative change = between your signal and Dex's seems rather high for that mechanism, but = I suppose not out of the question. AGARD CP 305 includes a paper = (Morfitt) with some interesting plots in this context, and a number of = other papers with interesting propagation studies at frequencies near = 74kHz; is there a good place for me to post info of this type? =20 73, =20 Jim AA5BW=20 =20 From: owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org] On Behalf Of Bob Raide Sent: Sunday, November 3, 2013 12:07 PM To: rsgb_lf_group@blacksheep.org Subject: LF: Hartmut's Grabber On Last Night... =20 Good shots of Me and Dex-Bob WG2XRS/4 NY [XRS4] and [XRS5]...=20 ------=_NextPart_000_0004_01CED8F9.3F50F690 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Alan,
 
based on Loran-C measurements, I = would agree=20 on the ballpark figure of -6 dB per hop. Not sure though if land = reflections are=20 really so much worse than seawater, as for low angle incidence the=20 reflection coefficient may still be close to unity.
 
> A 16dB fade suggests 20dB or so = difference in=20 amplitude.
 
No. -20 dB =3D 0.1 x amplitude for = the weaker=20 signal. But 1+-0.1 = =3D 1.1...0.9,=20 which would be a very flat fade (1.74 dB max to min). To=20 produce deep fades, the signals would need to be rather = similar in=20 magnitude.
 
73,
Markus (DF6NM)

From: Alan Melia
Sent: Monday, November 04, 2013 12:40 AM
Subject: LF: Re: RE: Hartmut's Grabber On Last=20 Night...

Hi Jim yes I think it is a phase = effect, the=20 reinforcement/cancellation is probably between 2 hop and 3 hop paths. A = 16dB=20 fade suggests 20dB or so difference in amplitude. I used to reckon on = about a=20 12dB per ionospheric hop and less, maybe 6dB, for a sea "bounce" based = on signal=20 from Joe VO1NA and the Naval station at Newport Corner near Halifax NS. = Each hop=20 has a maximum range of about 2000km. There are several effects around = the sunset=20 shadow area that could add to the effect too. Higher angles at the=20 ionosphere may penetrate futher before returning giving higher = attenuation to=20 the higher hop modes. 
 
A thumbnail calculation suggests hop3 = ampltude of=20 about -23dB below hop 2 would give a 17dB fade as it goes in and = out of=20 phase.
 
Very much a "hand waving" estimate but = a useful=20 empirical guide.
 
Alan
G3NYK
----- Original Message -----
From:=20 hvanesce=20
Sent: Sunday, November 03, 2013 = 8:56=20 PM
Subject: LF: RE: Hartmut's = Grabber On=20 Last Night...

Bob,

 

This=20 is the third time that I=92ve noticed Dex=92s signal peaking = substantially=20 (>15dB?) starting around 0500, at approximately the same time that = your=20 signal begins a substantial fade. I=92ve seen this twice on captures = from=20 Hartmut=92s grabber, and once on a capture from Mike=92s grabber.=20

 

An=20 interesting example is 21 October 2013, when captures by Henny, Mike = and=20 Hartmut all showed a fade of roughly 10-15dB in your signal from = 0500-0530,=20 with Mike=92s grabber (which showed Dex=92s signal clearly around that = time)=20 showing a rise in Dex=92s signal of roughly 10-15dB.=20  

 

I=20 wonder if this could be attributable to modal phase = reinforcement/cancellation=20 near the terminator? The relative change between your signal and = Dex=92s seems=20 rather high for that mechanism, but I suppose not out of the question. = AGARD=20 CP 305 includes a paper (Morfitt) with some interesting plots in this = context,=20 and a number of other papers with interesting propagation studies at=20 frequencies near 74kHz; is there a good place for me to post info of = this=20 type?

 

73,

 

Jim=20 AA5BW

 

From:=20 owner-rsgb_lf_group@blacksheep.org = [mailto:owner-rsgb_lf_group@blacksheep.org]=20 On Behalf Of Bob Raide
Sent: Sunday, November 3, 2013 = 12:07=20 PM
To: rsgb_lf_group@blacksheep.org
Subject: LF: = Hartmut's=20 Grabber On Last Night...

 

Good=20 shots of Me and Dex-Bob WG2XRS/4 NY [XRS4] and [XRS5]...=20

------=_NextPart_000_0004_01CED8F9.3F50F690--