|
Between 12 and 18 UT today, again Ossi's
fieldstrength has gradually decreased on Stefan's grabber in
Heidelberg (about 400 km), while it has increased for Lubos, Gerhard's
and myself (all ~ 200 km). It looks like it may have been increasing also
for Jacek (~ 700 km) but I'm not quite sure about the time scale of his
screenshot.
This seems to confirm that a) VLF interference
fringes are fairly reproducible from one day to another, and
b) they vary with range in a non monotonuous way, but do not
depend on direction or absolute positions.
Best wishes,
Markus (DF6NM)
Sent: Sunday, January 16, 2011 8:48 PM
Subject: Re: LF: OE3GHB_active
Dear Gerhard, VLF dreamers,
yes, this is indeed interesting. We are
probably seeing a phasing effect between skywave and groundwave (or should
I say between ionospheric waveguide modes), which depends on distance and solar
elevation. The constellation between our stations (two transmitters and two
receivers, roughly spaced 200, 400 and 600 km along a straight line)
seems to be favourable for this kind of observations.
On the MSK grabber segment, DHO exhibited
a remarkable frequency selective sunset dip, walking through
the emission band (200 Hz HF-to-LF in about 10 minutes). After 16:10, the VLF traces on my grabber were disrupted
due to local 137 kHz transmit activity.
Best wishes,
Markus (DF6NM)
Sent: Sunday, January 16, 2011 6:18 PM
Subject: Re: LF: OE3GHB_active
Dear Markus and group!
I'm not sure but probably
on your grabber there's a nice propagation
effect on VLF visible.
I
radiated all the time today with nearly constant power, except some 5
minutes
breaks and a half hours of downtime.
Ossi's signal also was very constant
all the time on his grabber which
is 10km away.
Starting from 12:00z
and lasting until about 14:00z my signal is clearly
stronger than Ossi's
signal, while at the moment, my signal isn't
visible any more and Ossi's
signal is still present, even maybe stronger
than most of the day.
On
Stefan's grabber this effect is not clearly visible.
This is quite
interesting.
73
OE3GHB
Gerhard
|
