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Alan
Thanks for the explanation...as always it's most
fascinating.
I hadn't noticed this effect in past
years...probably due to recent improvements in the receive setup that allow
me to "see" signals earlier and better than in previous years.
Keep me posted on the single hop
theory.
Jay
----- Original Message -----
Sent: Friday, January 13, 2006 10:11
AM
Subject: LF: Re: TA 13 JAN 06
Thanks for that comment Jay. I have just been discussing the
timing of
Brian's signal popping up on you screen, with him. We were trying
to decide
what the hop mode was and I was saying that the start of the
signal was
appearing in what I call the pre-sunset "dip" (**) this is not
so noticable
on E<>W signal but is much more noticable on N<>S
paths. My guess is that
this reduction in daytime skywave just before
sunset cuts back the noise you
are getting, by skywave, from the
"industrial centres". The signal from
Brian is reaching you when the
darkness edge at the altitude of the D/ lower
E-layer is only around
mid-path (about 1000km east of Newfoundland) thus the
intitial signal is
possibly a single hop (!!) I would have to plot a Great
circle from Brian
to you to determine this accurately. It is unlikely that
there is another
daytime skywave hop at the western end as, because of the
"dip" the D-layer
will not really support it late in the winter afternoon.
As the time
progresses, and the darkness edge moves closer to you, the 2 hop
signal
begins to rise in strength and the first thing it does is to
interfere with
the one hop, giving you a dip, or fade, then a rise to a
stronger
level. The two hop signal will always be stronger than the one hop,
which
has quite a struggle and is probably attenuated by diffraction at both
ends
of the path.
Thanks for sharing this information It is amazing what
interesting snippets
crop up, all helping to give me ideas about what going
on.
(**) see Brian's plots of DCF39 following the prop report on my web
site and
look at the difference between mid-day and morning and "evening"
(Tea time
in the UK.....but I dont want throwing in the harbour !! )
levels.
Cheers de Alan G3NYK
----- Original Message
-----
From: Jay Rusgrove <[email protected]>
To:
<[email protected]>
Sent:
13 January 2006 11:36
Subject: LF: TA 13 JAN 06
> Some static
good signal levels...captures at
> http://www.w1vd.com/gallery2006.html.
>
>
Over the past week or two I've been noticing a 'quiet period' before
>
local dark where the TA signals stand out unusually well. After that
>
period the signals seem to fade into the noise for an hour or two and
>
reappear at a stronger 'full' night time levels.
>
> Jay,
W1VD
>
>
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