Envelope-to: dave@picks.force9.co.uk
Delivery-date: Fri, 13 Jan 2006 15:13:14 +0000
Message-ID: <000e01c61853$962b2540$67b0fea9@lark>
From: "Alan Melia" <alan.melia@btinternet.com>
To: rsgb_lf_group@blacksheep.org
References: <000701c61835$9abc41c0$6401a8c0@JAYTERMINAL>
Date: Fri, 13 Jan 2006 15:11:06 -0000
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Subject: LF: Re: TA 13 JAN 06
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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 <JRusgrove@comcast.net>
To: <rsgb_lf_group@blacksheep.org>
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
>
>