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[195.171.43.25]) by mx.google.com with ESMTP id b10si4297415wiy.9.2013.11.03.18.03.59 for ; Sun, 03 Nov 2013 18:04:00 -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 (test mode) header.i=@btinternet.com Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Vd8yh-0004XX-BV for rs_out_1@blacksheep.org; Mon, 04 Nov 2013 01:29:15 +0000 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Vd8yg-0004XO-L8 for rsgb_lf_group@blacksheep.org; Mon, 04 Nov 2013 01:29:14 +0000 Received: from smtpout03.bt.lon5.cpcloud.co.uk ([65.20.0.123]) by relay1.thorcom.net with esmtp (Exim 4.77) (envelope-from ) id 1Vd8ye-0003BN-2V for rsgb_lf_group@blacksheep.org; Mon, 04 Nov 2013 01:29:13 +0000 X-CTCH-RefID: str=0001.0A090208.5276F866.0023,ss=1,re=0.100,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-Junkmail-Premium-Raw: score=39/97,refid=2.7.2:2013.11.1.83620:17:39.532,ip=81.157.1.97,rules=__HAS_MSGID, __SANE_MSGID, MSGID_32HEX_LC, INVALID_MSGID_NO_FQDN, __MSGID_32HEX, __HAS_FROM, __PHISH_FROM2, __FRAUD_WEBMAIL_FROM, __TO_MALFORMED_2, __TO_NO_NAME, __BOUNCE_CHALLENGE_SUBJ, __BOUNCE_NDR_SUBJ_EXEMPT, __MIME_VERSION, __CT, __CTYPE_MULTIPART_ALT, __CTYPE_HAS_BOUNDARY, __CTYPE_MULTIPART, __HAS_X_PRIORITY, __HAS_MSMAIL_PRI, __HAS_X_MAILER, USER_AGENT_OE, __OUTLOOK_MUA_1, __USER_AGENT_MS_GENERIC, __ANY_URI, __FRAUD_BODY_WEBMAIL, __URI_NO_WWW, __URI_NO_PATH, __SUBJ_ALPHA_NEGATE, SUPERLONG_LINE, __HTML_FONT_BLUE, __HAS_HTML, BODY_SIZE_10000_PLUS, __MIME_HTML, __TAG_EXISTS_HTML, __STYLE_RATWARE, __STYLE_RATWARE_NEG, RDNS_GENERIC_POOLED, __URI_NS, SXL_IP_DYNAMIC[97.1.157.81.fur], HTML_70_90, RDNS_SUSP_GENERIC, __PHISH_FROM, __OUTLOOK_MUA, RDNS_SUSP, __FRAUD_WEBMAIL, FORGED_MUA_OUTLOOK X-CTCH-Spam: Unknown Received: from gnat (81.157.1.97) by smtpout03.bt.lon5.cpcloud.co.uk (8.6.100.99.10161) (authenticated as alan.melia@btinternet.com) id 526ECB130081085B for rsgb_lf_group@blacksheep.org; Mon, 4 Nov 2013 01:29:10 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=btinternet.com; s=btcpcloud; t=1383528552; bh=8TJtpx4HLZSwi+FjFb9ESSzZxZ2hIaS9YtV0dfSDN+k=; h=Message-ID:From:To:References:Subject:Date:MIME-Version:Content-Type:X-Mailer; b=YREEVZeDWSZH7DDVFpHxpic2y5pFjbSt1eGZ2bOdPjus6Z1cTVmRHGC93R4I6aTnpJtotrAMD+fc2k9cUFKD+sRH8UN9uLBeNdsG4MTS848170nLhFxbjNgCv7dl90KRVHLLreSY3wr47TwC/SssyL1NqR8ItNiJXOYM8AUL6F0= Message-ID: From: "Alan Melia" To: References: <05b201ced8d7$24e85fe0$6eb91fa0$@comcast.net> <2FA25F9F5AB648A98C2F0C7A96F0D1B2@gnat> <02CA06069FC74FEAAEF85930320E0E34@White> Date: Mon, 4 Nov 2013 01:27:45 -0000 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 131103-1, 03/11/2013), 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....Ah used the wrong thumb :-)) yes I though it did seem odd..... I had taken the low level instead of the difference. A recalc gives hop 3 at -7dB wrt hop 2 that ties in nicely with your Loran figure. The sea hop estimate was based on 136kHz I just assumed that the sea was smoother than land in the wavelength dimension so less scattering. Overland signals to here seemed relatively weaker than Joe's signal, but there is all the problem with antenna efficiency to consider. and there were not many signals at 4000km at the time. Your Loran transmitters area more reliable source. Of course if you take maximum range, the "downcomming" wave comes in tangentialy so grazes rather than "reflects". Fascinating stuff....thanks for your correction....that thumb erased :-)) [...] 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 [65.20.0.123 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: 8a92398c4d799328418d0bdb7e7fa4f8 Subject: Re: LF: Re: RE: Hartmut's Grabber On Last Night... Content-Type: multipart/alternative; boundary="----=_NextPart_000_00BF_01CED8FD.10503320" 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_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 Status: O X-Status: X-Keywords: X-UID: 2880 This is a multi-part message in MIME format. ------=_NextPart_000_00BF_01CED8FD.10503320 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Hi Markus....Ah used the wrong thumb :-)) yes I though it did seem = odd..... I had taken the low level instead of the difference. A recalc = gives hop 3 at -7dB wrt hop 2 that ties in nicely with your Loran = figure. The sea hop estimate was based on 136kHz I just assumed that the = sea was smoother than land in the wavelength dimension so less = scattering. Overland signals to here seemed relatively weaker than Joe's = signal, but there is all the problem with antenna efficiency to = consider. and there were not many signals at 4000km at the time. Your = Loran transmitters area more reliable source. Of course if you take = maximum range, the "downcomming" wave comes in tangentialy so grazes = rather than "reflects". Fascinating stuff....thanks for your = correction....that thumb erased :-)) Alan ----- Original Message -----=20 From: Markus Vester=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Monday, November 04, 2013 12:00 AM Subject: Re: LF: Re: RE: Hartmut's Grabber On Last Night... 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_00BF_01CED8FD.10503320 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Hi Markus....Ah used the wrong thumb = :-)) yes I=20 though it did seem odd..... I had taken the low level instead of the = difference.=20  A recalc gives hop 3 at  -7dB wrt hop 2 that ties in nicely = with your=20 Loran figure. The sea hop estimate was based on 136kHz I just assumed = that the=20 sea was smoother than land in the wavelength dimension so less = scattering.=20 Overland signals to here seemed relatively weaker than Joe's signal, but = there=20 is all the problem with antenna efficiency to consider. and there were = not many=20 signals at 4000km at the time. Your Loran transmitters area more = reliable=20 source. Of course if you take maximum range, the "downcomming" wave = comes in=20 tangentialy so grazes rather than "reflects". Fascinating = stuff....thanks for=20 your correction....that thumb erased  :-))
 
Alan
----- Original Message -----
From:=20 Markus=20 Vester
Sent: Monday, November 04, 2013 = 12:00=20 AM
Subject: Re: LF: Re: RE: = Hartmut's=20 Grabber On Last Night...

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=20 are 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=20 in 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=20 signal from Joe VO1NA and the Naval station at Newport Corner near = Halifax NS.=20 Each hop has a maximum range of about 2000km. There are several = effects around=20 the sunset shadow area that could add to the effect too. Higher = angles at=20 the ionosphere may penetrate futher before returning giving higher = attenuation=20 to 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
To: rsgb_lf_group@blacksheep.org= =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=20 reinforcement/cancellation near the terminator? The relative change = between=20 your signal and Dex=92s seems rather high for that mechanism, but I = suppose=20 not out of the question. AGARD CP 305 includes a paper (Morfitt) = with some=20 interesting plots in this context, and a number of other papers with = interesting propagation studies at frequencies near 74kHz; is there = a good=20 place for me to post info of this type?

 

73,

 

Jim=20 AA5BW

 

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

 

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

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