Return-Path: Received: from mtain-dc03.r1000.mx.aol.com (mtain-dc03.r1000.mx.aol.com [172.29.64.131]) by air-mb07.mail.aol.com (v129.4) with ESMTP id MAILINMB073-a7a34c0a407624a; Sat, 05 Jun 2010 08:17:58 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dc03.r1000.mx.aol.com (Internet Inbound) with ESMTP id 959A93800011E; Sat, 5 Jun 2010 08:17:55 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OKsIw-0007P1-Ey for rs_out_1@blacksheep.org; Sat, 05 Jun 2010 13:16:46 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OKsIv-0007Os-V9 for rsgb_lf_group@blacksheep.org; Sat, 05 Jun 2010 13:16:45 +0100 Received: from imr-da06.mx.aol.com ([205.188.169.203]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OKsIs-0003qG-TD for rsgb_lf_group@blacksheep.org; Sat, 05 Jun 2010 13:16:45 +0100 Received: from mtaout-db01.r1000.mx.aol.com (mtaout-db01.r1000.mx.aol.com [172.29.51.193]) by imr-da06.mx.aol.com (8.14.1/8.14.1) with ESMTP id o55CGHfG009281 for ; Sat, 5 Jun 2010 08:16:17 -0400 Received: from White (g229230005.adsl.alicedsl.de [92.229.230.5]) by mtaout-db01.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 8C784E00009D for ; Sat, 5 Jun 2010 08:16:14 -0400 (EDT) Message-ID: <7F894944D7CD4E87A60BE1593D777585@White> From: "Markus Vester" To: References: <657E7065AC4C454AB63F6C7C2FF043F6@Black> <85A6EDF74C464FF09E93E97F768BA81F@JimPC> Date: Sat, 5 Jun 2010 14:16:11 +0200 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-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: Re: Two-Way QSO on Dreamer's Band Content-Type: multipart/alternative; boundary="----=_NextPart_000_000C_01CB04B9.A61C6250" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30,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 x-aol-global-disposition: G x-aol-sid: 3039ac1d40834c0a40730d9a X-AOL-IP: 193.82.116.20 ------=_NextPart_000_000C_01CB04B9.A61C6250 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Dear Jim, thank you for your comment. It's certainly a good idea to get some more quantitative data on our= VLF antennas, aiding optimisation, and ultimately getting a better id= ea on what long distance attenuation behaves like. On LF I have been= using a roughly calibrated system based on DCF 39 receive measurement= s, but on 9 kHz it's all just guesswork with a lot of uncertainty. Reviewing saved spectra from my narrowband grabber, the range of diurn= al and day-to-day noise level variations currently seems to be on the= order of 10 dB. This is after noise blanking at a 9 dB trigger thresh= old, and excluding times of regional thunderstorms. Yesterday night I= had temporarily changed the antenna configuration (inserted the loain= g coil and removed the preamp), so I can't give an accurate number her= e. Judging by the brightness on Stefan's and my grabbers, I would say= it was average, about 5 dB above the bottom. I would however guess= that during wintertime minima were perhaps another 5 dB lower. The noise blanker often seems to improve SNR by some 6 to 10 dB, howev= er there is a little uncertainty on how much it has cut out of the sig= nal amplitude. During an absolute measurement, it may be worthwile to= track gain by injecting an additional low-level test tone. Kind regards, Markus (DF6NM) From: James Moritz=20 Sent: Saturday, June 05, 2010 12:54 AM To: rsgb_lf_group@blacksheep.org=20 Subject: LF: Re: Two-Way QSO on Dreamer's Band Dear Markus, Walter, LF Group, Congratulations on the QSO - it is impressive to see that usable SNRs= can be=20 achieved in the far-field at 9kHz with quite small antennas and limite= d TX=20 power. A long term objective at M0BMU for 9kHz is to do some field str= ength=20 measurements using TX antennas on a similar scale. The main practical= =20 difficulty would seem to be the long time needed to integrate the sign= al at=20 the receiver in order to obtain an adequate SNR for useful measurement= s (and=20 to travel far enough to be out of the near field!) - I would be intere= sted=20 to know what SNR you would expect under "quiet" conditions using the= same TX=20 and RX parameters. Cheers, Jim Moritz 73 de M0BMU ----- Original Message -----=20 From: "Markus Vester" To: Sent: Friday, June 04, 2010 9:59 PM Subject: VLF: Two-Way QSO on Dreamer's Band Dear LF, this morning, June 4th between 6 and 8 UT, Walter (DJ2LF) and myself= (DF6NM)=20 were able to successfully conduct a two-way contact (aka "QSO") on 8.9= 7 kHz.=20 ------=_NextPart_000_000C_01CB04B9.A61C6250 Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Dear Jim,
 
thank you for your comment.
 
It's certainly a good idea to get som= e more=20 quantitative data on our VLF antennas, aiding optimisation, and= ultimately=20 getting a better idea on what long distance attenuation beha= ves like.=20 On LF I have been using a roughly calibrated system based on DCF= 39 receive=20 measurements, but on 9 kHz it's all just guesswork with a lot of= =20 uncertainty.
 
Reviewing saved spectra from my narro= wband grabber,=20 the range of diurnal and day-to-day noise level variations currently= seems to be=20 on the order of 10 dB. This is after noise blanking at a 9 dB tri= gger=20 threshold, and excluding times of regional=20 thunderstorms. Yesterday night I had temporarily changed the= antenna=20 configuration (inserted the loaing coil and removed the preamp),= so I can't=20 give an accurate number here. Judging by the brightness on Stefan= 's and my=20 grabbers, I would say it was average, about  5 dB above the= bottom. I=20 would however guess that during wintertime minima were perhaps another= 5 dB=20 lower.
 
The noise blanker often seems to= improve SNR=20 by some 6 to 10 dB, however there is a little uncertainty on how= much it=20 has cut out of the signal amplitude. During an absolute meas= urement,=20 it may be worthwile to track gain by injecting an additional low-= level test=20 tone.
 
Kind regards,
Markus (DF6NM)

Sent: Saturday, June 05, 2010 12:54 AM
Subject: LF: Re: Two-Way QSO on Dreamer's Band
=
=
Dear Mark= us, Walter, LF Group,

Congratulations on=20 the QSO - it is impressive to see that usable SNRs can be
achieved= in the=20 far-field at 9kHz with quite small antennas and limited TX
power.= A long=20 term objective at M0BMU for 9kHz is to do some field strength
meas= urements=20 using TX antennas on a similar scale. The main practical
difficult= y would=20 seem to be the long time needed to integrate the signal at
the rec= eiver in=20 order to obtain an adequate SNR for useful measurements (and
to tr= avel far=20 enough to be out of the near field!) - I would be interested
to kn= ow what=20 SNR you would expect under "quiet" conditions using the same TX
an= d RX=20 parameters.

Cheers, Jim Moritz
73 de M0BMU

----- Orig= inal=20 Message -----
From: "Markus Vester" <markusvester@aol.com>
To: <rsgb_lf_group@blacksheep.org&g= t;
Sent:=20 Friday, June 04, 2010 9:59 PM
Subject: VLF: Two-Way QSO on Dreamer'= s=20 Band


Dear LF,

this morning, June 4th between 6 and= 8 UT,=20 Walter (DJ2LF) and myself (DF6NM)
were able to successfully conduc= t a=20 two-way contact (aka "QSO") on 8.97 kHz.


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