Hi Stefan, this is a function of propagation, I think. It depends on where
the interference originates. Because there is virtually no skywave
propagation in the "sunrise dip", no noise is propagated by skywave (>
1000km) from the east. Where you live you have large cities all round you.
We get this effect on the edge of Europe as the daylight kills the
night-time propgation of noise fron the East (there a few big cities or
industrial noise sources for 3000 km W of Ireland
:-)) )
It was thought at first that this would be the best time for DX, but despite
trying it didnt work out that way. Mike G3XDV and Brian CT1DRP tried quite
hard..... but eventually made the qso mid morning, when the noise was up
again due to increases in daytime skywave!! That is if I remember
correctly.....it fascinated me as I was just getting interested in LF long
distance propagation around then. We found evening effects in Nova Scotia
and I believe similar effects were reported by John W1TAG and Jay W1VD who
are very close to the US East Coast.
Alan
G3NYK
----- Original Message -----
From: "Stefan Schäfer" <[email protected]>
To: <[email protected]>; "YV7MAE Maritn A. Echazarreta D."
<[email protected]>
Sent: Thursday, June 21, 2012 11:22 PM
Subject: LF: 15 dB noise drop in 20 minutes
Hello Martin, LF,
I'm fascinated by the noise drop on LF which occurs during your sunrise.
On your grabber
(http://dl.dropbox.com/u/74746618/LF/YV7MAE_LF_Grabber.html ), i can see
the noise drops 15 dB within 20 minutes. That means the sun must be very
strong so the ionosphere is very quickly ionized. Also the local lightning
density must be extreme. All in all it looks like a very sensitive system.
But some directivity would be interesting :-)
73, Stefan/DK7FC
PS: I will be on 136.172 kHz again this night, starting in a few
minutes...
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