Return-Path: Received: from mtain-mj06.r1000.mx.aol.com (mtain-mj06.r1000.mail.aol.com [172.21.164.90]) by air-mb07.mail.aol.com (v129.4) with ESMTP id MAILINMB071-a7844ca7c70c27e; Sat, 02 Oct 2010 19:58:04 -0400 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mj06.r1000.mx.aol.com (Internet Inbound) with ESMTP id EDA8138000089; Sat, 2 Oct 2010 19:57:59 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1P2BwU-0001Yl-AY for rs_out_1@blacksheep.org; Sun, 03 Oct 2010 00:56:38 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1P2BwJ-0001YK-SW for rsgb_lf_group@blacksheep.org; Sun, 03 Oct 2010 00:56:27 +0100 Received: from imr-ma05.mx.aol.com ([64.12.100.31]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1P2BwJ-0008QQ-HK for rsgb_lf_group@blacksheep.org; Sun, 03 Oct 2010 00:56:29 +0100 Received: from mtaout-db06.r1000.mx.aol.com (mtaout-db06.r1000.mx.aol.com [172.29.51.198]) by imr-ma05.mx.aol.com (8.14.1/8.14.1) with ESMTP id o92NuLAx020444 for ; Sat, 2 Oct 2010 19:56:21 -0400 Received: from Black (nrbg-4d0734eb.pool.mediaWays.net [77.7.52.235]) by mtaout-db06.r1000.mx.aol.com (MUA/Third Party Client Interface) with ESMTPA id 723EFE000096 for ; Sat, 2 Oct 2010 19:56:20 -0400 (EDT) Message-ID: <3B415F3E22FA40C7A9D10C9C16474E34@Black> From: "Markus Vester" To: References: <4CA5E86D.1070208@iup.uni-heidelberg.de> <6F6098420211436FABB78BE04E5F8FAD@JimPC> <000901cb6215$2db60550$0401a8c0@xphd97xgq27nyf> <4CA7096F.7070307@freenet.de> <25B77CFFDA13430086BE150894C4D3C3@Black> <5C71BB4133A642F7A2D06B26B567880D@Black> <65DFBC8F38CD4AF48A62C61B6BC4DCC4@Black> In-Reply-To: Date: Sun, 3 Oct 2010 01:56:13 +0200 MIME-Version: 1.0 X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Windows Mail 6.0.6000.16480 X-MimeOLE: Produced By Microsoft MimeOLE V6.0.6000.16669 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: VLF: Samplerate Stabilization Content-Type: multipart/alternative; boundary="----=_NextPart_000_0009_01CB629E.28A751C0" 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: 3039400c89ac4ca7c7074ee4 X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0009_01CB629E.28A751C0 Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable Dear Jim, that is an excellent reception! But looking at the screenshot immediat= ely sent me fumbling for my eyeglasses ;-) The strong line appears to= be split up by a regular ~ 10 mHz modulation, in agreement with the= observed temperature cycle.=20 A possible remedy could lie in SpecLab's MSK-based samplerate tracking= function. Here I've been locking to GBZ 19.58 kHz for a few weeks now= , with next-to-perfect stability. You may want to reduce the integrati= on time (Ud. cycle, default 10s) to track faster variations, but being= close to the transmitter there should be plenty of SNR available. 73, Markus (DF6NM) ----- Original Message -----=20 From: James Moritz=20 To: rsgb_lf_group@blacksheep.org=20 Sent: Sunday, October 03, 2010 12:42 AM Subject: LF: Re: DK7FC's 7th VLF kite experiment Dear Stefan, LF Group, This is the screen shot of today's signal from DK7FC at my home QTH= (IO91vr)=20 from about 1020 until 1300 utc. The time markers are at 1 hour inter= vals.=20 The QRN level seemed to be quite low. The horizontal streaks are loc= al=20 mains-related QRM. My laptop decided to switch itself off at about= the time=20 Stefan's transmission started, but fortunately I was present at the= time and=20 only a few minutes of signal were lost. The SNR reached about 15dB= with 3=20 millihertz FFT resolution - I think if the maximum ERP could be main= tained,=20 copy of QRSS60 or QRSS30 signals would be possible under these condi= tions. A spectrogram with this resolution begins to show the limitations of= using=20 the laptop's internal sound card. The start of the trace shows the= warm-up=20 drift of the sound card, which isn't too bad. But you can see that= the=20 signal trace is spread over several FFT bins, apparently due to some= =20 short-term instability of the sampling rate. I think this is due to= the=20 cooling fan in the laptop cycling on and off every minute or two, fr= equency=20 modulating the soundcard clock by several millihertz due to the cha= nging=20 temperature. I think if this instability could be eliminated, the SN= R would=20 be improved by some dBs. Probably an external sound card would be a= good=20 idea. Thanks to Stefan for another successful VLF test, Cheers, Jim Moritz 73 de M0BMU=20 ------=_NextPart_000_0009_01CB629E.28A751C0 Content-Type: text/html; charset="ISO-8859-15" Content-Transfer-Encoding: quoted-printable
Dear Jim,
 
that is an excellent reception! But= looking at the=20 screenshot immediately sent me fumbling for my eyeglasses ;-) The stro= ng line=20 appears to be split up by a regular ~ 10 mHz modulation, in agree= ment with=20 the observed temperature cycle.
 
A possible remedy could lie in&n= bsp;SpecLab's=20 MSK-based samplerate tracking function. Here I've been locking to=20 GBZ 19.58 kHz for a few weeks now, with next-to-perfect stab= ility. You=20 may want to reduce the integration time (Ud. cycle, default 10s)= to track=20 faster variations, but being close to the transmitter there should be= plenty of=20 SNR available.
 
73, Markus (DF6NM)
 
----- Original Message -----
From:=20 James Moritz
Sent: Sunday, October 03, 201= 0 12:42=20 AM
Subject: LF: Re: DK7FC's 7th= VLF kite=20 experiment
=
Dear Stefan, LF=20 Group,

This is the screen shot of today's signal from DK7FC= at my home=20 QTH (IO91vr)
from about 1020 until 1300 utc. The time markers ar= e at 1=20 hour intervals.
The QRN level seemed to be quite low. The horizo= ntal=20 streaks are local
mains-related QRM. My laptop decided to switch= itself=20 off at about the time
Stefan's transmission started, but fortuna= tely I was=20 present at the time and
only a few minutes of signal were lost.= The SNR=20 reached about 15dB with 3
millihertz FFT resolution - I think if= the=20 maximum ERP could be maintained,
copy of QRSS60 or QRSS30 signal= s would be=20 possible under these conditions.

A spectrogram with this reso= lution=20 begins to show the limitations of using
the laptop's internal so= und card.=20 The start of the trace shows the warm-up
drift of the sound card= , which=20 isn't too bad. But you can see that the
signal trace is spread= over=20 several FFT bins, apparently due to some
short-term instability= of the=20 sampling rate. I think this is due to the
cooling fan in the lap= top=20 cycling on and off every minute or two, frequency
modulating the= soundcard=20 clock  by several millihertz due to the changing
temperatur= e. I think=20 if this instability could be eliminated, the SNR would
be improv= ed by some=20 dBs. Probably an external sound card would be a good
idea.
Thanks=20 to Stefan for another successful VLF test,

Cheers, Jim Moritz=
73 de=20 M0BMU
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