Message-ID: <61837EC08D2546078D392EC60ED384C5@White>
From: "Markus Vester" <markusvester@aol.com>
To: <rsgb_lf_group@blacksheep.org>
References: <33d07ccc43ec486d83d0d460928f26ad@kabelmail.de><AANLkTimhxKt3FxUtStDVeu3LnumSdQ7CtbqzOouVDOdT@mail.gmail.com><4D77A449.1040603@iup.uni-heidelberg.de> <AANLkTi=93aaaD6+9PdhWFUTv-2=2hfjoamYqExd+nNyW@mail.gmail.com>
Date: Wed, 9 Mar 2011 22:46:37 +0100
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Subject: VLF: G3XBM grabber
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Dear Roger,

just one suggestion: perhaps you could soften the display contrast a=
 bit, to=20
allow better visibility during the daytime periods when QRN is low.

The strange 8970.1 signature is very narrow so certainly of human orig=
in,=20
and probably crystal controlled. Could be some timer-activated device=
 in the=20
neighbourhood.

Best 73,
Markus (DF6NM)


From: Roger Lapthorn
Sent: Wednesday, March 09, 2011 5:20 PM
To: rsgb_lf_group@blacksheep.org ; Stefan Sch=E4fer
Subject: Re: LF: VLF dj8wx on 8970.022Hz

Hi Stefan,

I enclose here the full wider band 3 day plot of the noise (and myster=
y=20
signal) as received in 424uHz BW here in JO02dg near Cambridge. Do you=
 have=20
any comments please? The mystery signal appears on all three nights at=
=20
8.9701kHz. It looks like a little "hook" shape over about 4 hours.

BTW, the loop/preamp system is receiving the alpha beacons very well,=
=20
typically 20dB over the noise. See=20
http://www.youtube.com/watch?v=3DTDxRhQYg7lQ for a video showing alpha=
 beacon=20
reception using the SM6LKM software VLF receiver.

If the interference/noise at 8.9701kHz was natural then surely it woul=
d be=20
amazing for such signals to exactly repeat 3 nights running at exactly=
 the=20
same frequency? OK, I agree the general background noise floor may be=
 partly=20
man made and partly the natural noise floor changing diurnally but the=
=20
oddity at 8.9701kHz?

The grabber is currently OFF as I shall be away for a couple of days,=
 but=20
still in email contact.

73s
Roger G3XBM


2011/3/9 Stefan Sch=E4fer <Stefan.Schaefer@iup.uni-heidelberg.de>

Hello Roger,
Am 08.03.2011 20:51, schrieb Roger Lapthorn:


Nothing visible on my grabber https://dl.dropbox.com/u/15047843/xbm_gr=
ab.jpg=20
yet this evening but I have a high noise level in the evening hours fr=
om=20
lights, TVs etc.Leave the TX running overnight please as I hope to see=
 your=20
signal after midnight and through tomorrow morning. In the 423uHz band=
width=20
and with the slow scroll speed it will be more difficult to see than=
 when=20
you were sending a continuous carrier a few days ago.



Are you sure it is local QRM? Maybe its just the usual QRN that risies=
=20
strongly in the evening. It is as strong as never before within this=
 year=20
now :-( And things will get even worse. We have to make QRO, faster th=
an=20
nature does it ;-)

To check the local QRN/QRM situation it would be helpful (and interest=
ing!)=20
to have a wideband screen from you. If you want, you could run a secon=
d SL=20
instance simultaneously and upload the pictures. You know how the wide=
band=20
windows looks, from grabbers like TF3HZ which is most interesting each=
 day=20
:-)

Also you may arrange a real website and store it on your dropbox. Ther=
e you=20
can include several pictures in one link, the link to the website :-)

Best 73, Stefan/DK7FC