I think the signal was a little stronger this time. But
I'm afraid, not clear enough to decode. Yes I can see the
two K, but only when I know they are there. If I didn't know
what the message was, it would be ambiguous.
Background noise was in the same direction as the signal to
begin with and the first K was in the null of the beam. It's
there on the omni-directional spectrogram - here are the two,
http://abelian.org/vlf/ss100321/orient.png
http://abelian.org/vlf/ss100321/omni.png
By the end of the transmission, the noise had shifted around almost
North/South and Frankfurt was nicely in the beam so no difference
of signal between omni and oriented.
There's a little problem here with the soundcard clock discipline,
it's jumping around quite a bit more than it should, I think it's
spreading the signal. Those final two dots were the sharpest
and the frequency lock was best then. Time constant is a bit
too short - supposed to keep up with rapid change of soundcard xtal
but I think it's just responding to changes in MSF 60kHz signal.
Will reprocess from the raw without the clock control and see how
that looks.
Signal at DF6NM is the only clear copy at DFCW-600, no doubt about
the message there. IK1QFK got a good signal, range 544km, might
be able to decode that if the spectrogram is redrawn better.
http://abelian.org/vlf/live/vlf15.sg.png
Certainly looks like its all there, including the tune-up.
Rest of us still have a way to go. Many thanks to Stefan for another
interesting test!
(Still a fair bit of whistler activity, 560 logged so far this
evening, but getting weaker now.)
--
Paul Nicholson
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