Return-Path: Received: from mtain-mc04.r1000.mx.aol.com (mtain-mc04.r1000.mx.aol.com [172.29.96.76]) by air-ma10.mail.aol.com (v129.4) with ESMTP id MAILINMA103-b5424c3b3d85b0; Mon, 12 Jul 2010 12:06:29 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-mc04.r1000.mx.aol.com (Internet Inbound) with ESMTP id F3C2A38000144; Mon, 12 Jul 2010 12:06:26 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OYLVT-0006ml-8o for rs_out_1@blacksheep.org; Mon, 12 Jul 2010 17:05:23 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OYLVS-0006mc-9v for rsgb_lf_group@blacksheep.org; Mon, 12 Jul 2010 17:05:22 +0100 Received: from imr-da02.mx.aol.com ([205.188.105.144]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OYLVQ-0002TP-3k for rsgb_lf_group@blacksheep.org; Mon, 12 Jul 2010 17:05:22 +0100 Received: from imo-ma02.mx.aol.com (imo-ma02.mx.aol.com [64.12.78.137]) by imr-da02.mx.aol.com (8.14.1/8.14.1) with ESMTP id o6CG51C1005644 for ; Mon, 12 Jul 2010 12:05:01 -0400 Received: from MarkusVester@aol.com by imo-ma02.mx.aol.com (mail_out_v42.9.) id l.e7a.401e1a0 (43955) for ; Mon, 12 Jul 2010 12:04:58 -0400 (EDT) Received: from smtprly-dd02.mx.aol.com (smtprly-dd02.mx.aol.com [205.188.84.130]) by cia-dd01.mx.aol.com (v129.4) with ESMTP id MAILCIADD014-d3f24c3b3d1e155; Mon, 12 Jul 2010 12:04:57 -0400 Received: from webmail-d018 (webmail-d018.sim.aol.com [205.188.181.29]) by smtprly-dd02.mx.aol.com (v129.4) with ESMTP id MAILSMTPRLYDD026-d3f24c3b3d1e155; Mon, 12 Jul 2010 12:04:46 -0400 References: <002301cb1e8c$d28d4740$4001a8c0@lark> <4C35C346.7080307@iup.uni-heidelberg.de> To: rsgb_lf_group@blacksheep.org Date: Mon, 12 Jul 2010 12:04:46 -0400 In-Reply-To: <4C35C346.7080307@iup.uni-heidelberg.de> X-MB-Message-Source: WebUI MIME-Version: 1.0 From: Markus Vester X-MB-Message-Type: User X-Mailer: AOL Webmail 32213-STANDARD Received: from 194.138.39.61 by webmail-d018.sysops.aol.com (205.188.181.29) with HTTP (WebMailUI); Mon, 12 Jul 2010 12:04:46 -0400 Message-Id: <8CCEFF31532044C-1280-1D93@webmail-d018.sysops.aol.com> X-AOL-VSS-CODE: clean X-AOL-VSS-INFO: 5400.1158/0 X-Spam-Flag:NO X-AOL-SENDER: MarkusVester@aol.com X-Spam-Score: 2.1 (++) X-Spam-Report: autolearn=disabled,FORGED_AOL_TAGS=0.281,HTML_MESSAGE=0.001,TVD_FW_GRAPHIC_NAME_LONG=1.8,UNPARSEABLE_RELAY=0.001 Subject: Re: VLF: TA DX on the dreamers band? Content-Type: multipart/mixed; boundary="--------MB_8CCEFF3153B89D4_1280_40AD_webmail-d018.sysops.aol.com" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.1 required=5.0 tests=FORGED_AOL_TAGS, HTML_FONTCOLOR_UNKNOWN,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-VSS-INFO: 5400.1158/60807 X-AOL-VSS-CODE: clean x-aol-sid: 3039ac1d604c4c3b3d82452a X-AOL-IP: 193.82.116.20 ----------MB_8CCEFF3153B89D4_1280_40AD_webmail-d018.sysops.aol.com Content-Type: multipart/alternative; boundary="--------MB_8CCEFF3153B89D4_1280_40AE_webmail-d018.sysops.aol.com" ----------MB_8CCEFF3153B89D4_1280_40AE_webmail-d018.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Dear Stefan, Alan, LF, possibly the signal from Alpha Novosibirsk (4782 km east of here) on 11.9= kHz could provide a hint for transatlantic VLF propagation across a simil= ar range. The attached sketch qualitatively shows a "winged-W" diurnal beh= aviour of fieldstrength, based on several days of observations near the Ma= rch equinox: http://df6nm.bplaced.net/VLF/Alpha/Alpha_levels.png,=20 http://df6nm.bplaced.net/VLF/Alpha/Alpha_levels_3days.png As expected, attenuation is generally lowest and relatively constant over= a six hour period when the whole path is in darkness. After sunrise at= the transmitter at the eastern end of the path, the level began to decrea= se gradually, until a 15 dB minimum was reached shortly before sunrise at= the receiver. Thereafter, daytime fieldstrength across the fully lit path= followed solar elevation, with an increase of about 5 dB during the midda= y maximum. After sunset at the transmitter, a second minimum occured, foll= owed by a build-up until the path has become fully dark again. To estimate SNR, I have also attempted to plot a crude approximation of di= urnal noise levels, as seen here on 9 kHz aftere noise blanking. The range= of variation is usually some 5 to 10 dB, with a minimum around 8 h local= time. Of course we see a lot of day to day variation in the lightning act= ivity.=20 Thus best SNR would be expected during the six hours of common darkness,= and additionally for a couple of daytime hours after the morning noise mi= nimum.=20 I'm no sure about how much an all-water TA route would be different from= the Russian overland path. The surface reflections in "multihop" modes wi= ll generally benefit from conductivity and smoothness, but the difference= should be less pronounced at VLF. Regarding noise, the QRN pattern might= be delayed or differently shaped on the east coast of a continent, becaus= e lightning activity tends to be higher over land masses. Continuous state= side VLF noise observations or grabbers could provide valuable input. Best 73,=20 Markus (DF6NM) -----Urspr=C3=BCngliche Mitteilung-----=20 Von: Stefan Sch=C3=A4fer An: rsgb_lf_group@blacksheep.org Verschickt: Do., 8. Jul. 2010, 14:23 Thema: VLF: TA DX on the dreamers band? Alan,=20 =20 Which time (UTC) would be your recommendation for trying a transatlantic= DX reception on 9 kHz, say to canada?=20 Any ideas?=20 =20 Other experts are asked as well here!=20 =20 =20 ----------MB_8CCEFF3153B89D4_1280_40AE_webmail-d018.sysops.aol.com Content-Transfer-Encoding: quoted-printable Content-Type: text/html; charset="utf-8"

Dear Stefan, Alan, LF,
 
possibly the signal from Alpha Novosibirsk (4782 km east of here) on= 11.9 kHz could provide a hint for transatlantic VLF propagation across a&= nbsp;similar range. The attached sketch qualitatively shows a "winged-W"= diurnal behaviour of fieldstrength, based on several days of observations= near the March equinox:
http://df6= nm.bplaced.net/VLF/Alpha/Alpha_levels.png,
http= ://df6nm.bplaced.net/VLF/Alpha/Alpha_levels_3days.png
 
As expected, attenuation is generally lowest and relatively constant= over a six hour period when the whole path is in darkness. After  su= nrise at the transmitter at the eastern end of the path, the level began= to decrease gradually, until a 15 dB minimum was reached shortly before= sunrise at the receiver. Thereafter, daytime fieldstrength across the ful= ly lit path followed solar elevation, with an increase of about 5 dB durin= g the midday maximum. After sunset at the transmitter, a second minimum oc= cured, followed by a build-up until the path has become fully dark again.<= /div>
To estimate SNR, I have also attempted to plot a crude approximation= of diurnal noise levels, as seen here on 9 kHz aftere noise blanking. The= range of variation is usually some 5 to 10 dB, with a minimum around 8 h= local time. Of course we see a lot of day to day variation in the lightni= ng activity.
 
Thus best SNR would be expected during the six hours of common darkne= ss, and additionally for a couple of daytime hours after the morning noise= minimum.
 
I'm no sure about how much an all-water TA route would be different= from the Russian overland path. The surface reflections in "multihop" mod= es will generally benefit from conductivity and smoothness, but the differ= ence should be less pronounced at VLF. Regarding noise, the QRN pattern mi= ght be delayed or differently shaped on the east coast of a continent, bec= ause lightning activity tends to be higher over land masses. Continuous st= ateside VLF noise observations or grabbers could provide valuable input.
 
Best 73,
Markus (DF6NM)

-----Urspr=C3=BCngliche Mitteilung-----
Von: Stefan Sch=C3=A4fer <Stefan.Schaefer@iup.uni-heidelberg.de>
An: rsgb_lf_group@blacksheep.org
Verschickt: Do., 8. Jul. 2010, 14:23
Thema: VLF: TA DX on the dreamers band?

Alan, 
 
Which time (UTC) would be your recommendation for trying a transatlantic= DX reception on 9 kHz, say to canada? 
Any ideas? 
 
Other experts are asked as well here! 
 
 
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