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References: <4CA0EB84.9010708@iup.uni-heidelberg.de>
Date: Mon, 27 Sep 2010 13:46:37 -0700 (PDT)
From: Daniele Tincani <danieletincani@yahoo.com>
To: rsgb_lf_group@blacksheep.org
In-Reply-To: <4CA0EB84.9010708@iup.uni-heidelberg.de>
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Subject: Re: VLF: Earth antenna DX on 8970 Hz confirmed
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Hello Stefan, VLF,

in your knowledge, are Michael's settings for clipper/blanker=A0valid=A0re=
gardless=20
of the=A0rx signal level or they need adjustment for farther stations?

Best regards
Daniele




________________________________
From: Stefan Sch=E4fer <schaefer@iup.uni-heidelberg.de>
To: rsgb_lf_group@blacksheep.org
Sent: Mon, September 27, 2010 9:07:48 PM
Subject: VLF: Earth antenna DX on 8970 Hz confirmed

VLF,

Last saturday, Michael Oexner has successfully and undoubtly received the=
=20
message i transmitted on the 600m spaced earth electrode antenna on 8970=
 Hz. His=20
RX antenna is a PA0RDT design. SpecLab was used to receive the signals.

The applied TX power was about 250 W and the mode was DFCW-600. The antenn=
a=20
current was measured to be 530 mA. The QRN was reasonably low although it=
 could=20
have been better to transmit 2 hours before.

There are 2 screenshots in one picture: The upper (in UTC) shows the resul=
t with=20
a SpecLab internal band filter (BW=3D 6 kHz, centered arround 9 kHz). A cl=
ipping=20
level of 6 dB was applied + the noise blanker set to 0.002/9/0.05. The low=
er (in=20
UTC+2h) shows the same signal without using the internal SpecLab filter an=
d=20
without clipper, so just the blanker. You can see the difference! This mea=
ns, as=20
impressive demonstrated by Paul Nicholson on http://abelian.org/vlf/ss1008=
01/,=20
that bandfiltering is very important on VLF. Mostly it means to exclude th=
e=20
mains hum and the strong MSK transmitters. A too narrow filter is not opti=
mal=20
since the blanker has to "see" the QRN to blank it then. Thus i modified=
 my VLF=20
grabber circuit and have thrown out the 9 kHz band filter.

After increasing the earth antennas efficiency soon, the signal should be=
 up to=20
10 dB stonger :-)

73, Stefan/DK7FC


     =20

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<html><head><style type=3D"text/css"><!-- DIV {margin:0px;} --></style></h=
ead><body><div style=3D"font-family:arial, helvetica, sans-serif;font-size=
:10pt"><DIV>Hello Stefan, VLF,</DIV>
<DIV>&nbsp;</DIV>
<DIV>in your knowledge, are Michael's settings for clipper/blanker&nbsp;va=
lid&nbsp;regardless of the&nbsp;rx signal level or they need adjustment fo=
r farther stations?</DIV>
<DIV>&nbsp;</DIV>
<DIV>Best regards</DIV>
<DIV>Daniele<BR></DIV>
<DIV style=3D"FONT-FAMILY: arial, helvetica, sans-serif; FONT-SIZE: 10pt">=
<BR>
<DIV style=3D"FONT-FAMILY: times new roman, new york, times, serif; FONT-S=
IZE: 12pt"><FONT size=3D2 face=3DTahoma>
<HR SIZE=3D1>
<B><SPAN style=3D"FONT-WEIGHT: bold">From:</SPAN></B> Stefan Sch=E4fer &lt=
;schaefer@iup.uni-heidelberg.de&gt;<BR><B><SPAN style=3D"FONT-WEIGHT: bold=
">To:</SPAN></B> rsgb_lf_group@blacksheep.org<BR><B><SPAN style=3D"FONT-WE=
IGHT: bold">Sent:</SPAN></B> Mon, September 27, 2010 9:07:48 PM<BR><B><SPA=
N style=3D"FONT-WEIGHT: bold">Subject:</SPAN></B> VLF: Earth antenna DX on=
 8970 Hz confirmed<BR></FONT><BR>VLF,<BR><BR>Last saturday, <B>Michael Oex=
ner</B> has successfully and <B>undoubtly received</B> <B>the message</B>=
 i transmitted on the 600m spaced earth electrode antenna on <B>8970 Hz.=
 </B>His RX antenna is a PA0RDT design. SpecLab was used to receive the si=
gnals.<BR><BR>The applied TX power was about 250 W and the mode was DFCW-6=
00. The antenna current was measured to be 530 mA. The QRN was reasonably=
 low although it could have been better to transmit 2 hours before.<BR><BR=
>There are 2 screenshots in one picture: The upper (in UTC) shows the resu=
lt with a SpecLab
 internal band filter (BW=3D 6 kHz, centered arround 9 kHz). A clipping le=
vel of 6 dB was applied + the noise blanker set to 0.002/9/0.05. The lower=
 (in UTC+2h) shows the same signal without using the internal SpecLab filt=
er and without clipper, so just the blanker. You can see the difference!=
 This means, as impressive demonstrated by Paul Nicholson on http://abelia=
n.org/vlf/ss100801/, that bandfiltering is very important on VLF. Mostly=
 it means to exclude the mains hum and the strong MSK transmitters. A too=
 narrow filter is not optimal since the blanker has to "see" the QRN to bl=
ank it then. Thus i modified my VLF grabber circuit and have thrown out th=
e 9 kHz band filter.<BR><BR>After increasing the earth antennas efficiency=
 soon, the signal should be up to 10 dB stonger :-)<BR><BR>73, Stefan/DK7F=
C<BR><BR><BR></DIV></DIV></div><br>

      </body></html>

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