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The OE3GHB grabber shows a long bright
line on 8969.98 from 16:00 to 4:30. The sensitivity was not degraded,
so perhaps only a local oscillator test.
Or a nighttime carrier from OK2BVG? But it looks
stronger than the subsequent "KKK" which Lubos sent on 8970.02 / .04 from
6:00 to 15:45.
OE5ODL then shows a very bright "riser" from 6:15
to 14:15. This was his own transmission, also visible at DK7FC.
So probably two different signals, both on
8969.98. Could it be that Roger's screenshot has hints of
both?
Best 73,
Markus (DF6NM)
Sent: Tuesday, March 15, 2011 11:13 PM
Subject: LF: VLF reception - easily mistaken!
A word of caution to those of us looking for very
weak signals around 8-9kHz.....
DJ8WX was copied here overnight without
any doubt and my grabber was clearly able to see his close-down around 0700
today. The frequency and the trace timing corresponded perfectly. Likewise with
G3XIZ and DK7FC/P some weeks ago.
This evening I was looking very
carefully again at the Spectrum Lab screen from the last 24 hours in 424uHz BW
and readjusting audio gain ranges, screen colour saturation and contrast. Out of
the noise appeared another very very faint line, not at 8.970022 but at
8.96998kHz. I've attached the screen shot here (I have overlaid it with the time
for clarity).
My immediate reaction was this must be Ossi OE5ODL. Then I
checked his grabber and saw he was not operational overnight last night! So,
what looked like a trace on his frequency cannot be him. It must instead
be some artefact of SL or something else.
So, Mal is right (did I
just say that? :-) ) that we have to be very careful when seeing traces
at specific frequencies: it may be an indication of a given station, but without
some modulation or turning on/off of the carrier a doubt remains.
Sadly I
don't think I did see Ossi today after all, but I shall keep looking.
73s
Roger G3XBM
--
g3xbm-qrp.blogspot.com/
www.g3xbm.co.uk
www.youtube.com/user/g3xbm
G3XBM GQRP 1678 ISWL
G11088
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