|
Hi Jay, yes a quick check on the Dst does not show
a drop until late on the 25th (then only to -40nT) which is too late to enhance
the SAQ transmissions. There are lots of reasons for variability. I have just
seen an article mentioning changes in "transparency" due to "acoustic" waves in
the ionosphere. This may only apply to much higher frequencies but I need to
buckle down and try and understand the effect, and see whether there is any
relevance to LF/VLF
Some Great Work going on!!
Best Wishes
Alan
G3NYK
----- Original Message -----
Sent: Saturday, March 08, 2014 1:51
PM
Subject: LF: Re: Re: Daytime 29.499
kHz
Alan
Thanks for weighing in.
FWIW, the best receptions of SAQ 17.2 kHz at this
location (up until the most recent 12/24/13) have occured during their 'late'
vs. 'early' session which puts the receiving end well into
daylight ... and summer reception has been generally better
than winter.
The most recent reception on 12/24/13
was noticeably out of the ordinary as the best ever s/n was noted. A
short unprocessed mp3 is at:
Looking through the archives it appears
there were several M class flares on the days leading up to the
transmission. This latest reception might make a good 'case study' for someone
with the right capabilities.
Jay W1VD WD2XNS WE2XGR/2
WG2XRS/2
----- Original Message -----
Sent: Friday, March 07, 2014 6:54
PM
Subject: LF: Re: Daytime 29.499
kHz
Hi Markus this dome shape, peaking at mid-day
at mid-path, is very clear on all LF and VLF plots, and yes it does get
better in summer!! Also I have found that daytime mid-day levels are
enhanced for a day and sometimes two days after a geomagnetic storm, due I
think to the extra electron density in the D-layer from precipitated "hot"
electrons.....being hot they take longer to decay than photo-dissociated
electrons even at 50km altitude. The daytime enhancement can be as much as
6dB after a Geomag storm, useful but not as much as to give similar levels
as night-time. The "waveguide" is also narrower in daytime, so the signal
contact the lossy region more often. We have predicted these on 136 and the
effect on short paths was confirmed by John W1TAG and Jay W1VD. This
confirms that "ionosheric-wave" is present in daytime, and at distance it is
not all ground-wave.
Alan
G3NYK
----- Original Message -----
Sent: Friday, March 07, 2014 10:33
PM
Subject: LF: Daytime 29.499 kHz
Guess this thread needs a new
title...
It seems that the broad midday maximum appears
consistently on different medium-range VLF
paths, also on most 100 kHz Loran-C traces. Simplistic interpretation: With higher solar elevation,
ionisation penetrates to lower layers and produces a steeper
conductivity gradient, quite in analogy to a metal mirror. However this
would predict that midday reflection would be stronger in
summer?
Looking forward to Bob's test tomorrow!
Best 73,
Markus
(DF6NM)
Sent: Friday, March 07, 2014 11:16 PM
Subject: RE: LF: New OPERA OP/OPDS 2H tonight on 27.945 Dial
Freq...
Markus,
I?m
glad that you suggested a 2-hour time slot (if it works for Bob). Based on
your NAA spectrogram (attached), the window that you?re shooting for may
be a multimode interference peak, which might be shifted (an hour or so?)
for a Penn Yan path; and I don?t know which direction in time the window
would shift.
Paul
is doing so many things that I hate to mention this, but I wonder if LWPC
would show the interference peak near 1500 UT; and if so, which direction
in time the peak would shift for the Penn Yan path.
I
seem to remember that Paul provided an online interface to LWPC, I?ll see
if I can find it.
73,
Jim AA5BW
how about a
straight carrier on 29.499, from 14 to 16 UT? The narrow grabbers
will be on even if I have to be away. Results may depend on the
qrn situation here (aka Eu weather).
Sent: Friday, March
07, 2014 10:29 PM
Subject: RE: LF: New
OPERA OP/OPDS 2H tonight on 27.945 Dial
Freq...
Markus;
With you
home [not at work] tomorrow lets try around that 1500. I left the
signal on two nights ago till 1200 but after 0800 signal was gone till
2400 next night.
What mode and what time you want signal?
Bob
From: [email protected]
To: [email protected]
Date:
Fri, 7 Mar 2014 21:45:19 +0100
Subject: Re: LF: New OPERA OP/OPDS 2H
tonight on 27.945 Dial Freq...
I would think
that the main difference between Todmorden and Nuernberg is that I'm into
the sunrise dip an hour earlier. And my noise background is higher, so I
tend to completely lose a weak signal which Paul would still receive
well.
Anyway looking
at the attached NAA plot I'm sort of perplexed by the
strong propagation during the day. If Bob decided to transmit
sometime around 15 UT, there's a good chance we'd pick it
up.
|
