Message-ID: <003901c09f82$336e37c0$281a7bd5@default>
From: "Alan Melia" <Alan.Melia@btinternet.com>
To: "LF-Group" <rsgb_lf_group@blacksheep.org>
Subject: LF: Propagation ...SXV plots
Date: Sun, 25 Feb 2001 23:04:46 -0000
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Hi all, no not boring Trans-Atlantic again.....maybe be something of more
general interest. After the 'off' period of SXV (Marathon) last week I
decided that as I was getting 'withdrawal symptoms' because CFH has been
missing for so long, I would do a few plots of SXV to 'keep my hand in'. The
results are actually quite interesting. So much so I am sorry I did not
consider measuring it before.

I have only plotted SXV for 84 hours now but there are some surprising
features. First the signal is at its all time worst at about 0530 to 0830z
!! This is the magic morning time we have all assumed to be good.  ( This
may have implications for anyone trying to set up a sked with Brain in
CT-land) Second there is a very consistent wide dip in signal which has
occurred with a minimum within a few minutes of 1500z every day. (No I dont
think it is the tea-break time at the TX site! the dip is about 10dB and the
signals takes about 20mins to decline and another 20 mins to return) This is
a most odd effect as all the other features differ from day to day, except
at sun-down and sun-up.

The best time seems to be midnight to about 0400z, but the post dawn period
0900 to 1200z seems to be very consistent and not far behind with level
about 6dB lower. Evening conditions are quite good climbing steadily to a
peak at about midnight (though often as peaking as early as 2100z if there
are no deep fades to cut the signal up)

This is a path of about 2500kms with a long sea-reach up the Adriatic before
crossing the Alps, so it may not be directly comparable with inland paths.
It may however explain why I often seem to have seen Valerio on QRSS at
better strength in the late morning that earlier.

I do not have enough data yet to explain the variations but it looks as
though the continuation of these measurements could prove to be interesting.
I suppose if this is the case it might also prove to be useful to log the
daytime signal strength from DCF39 accurately.

.GIF files in 12hour slices can be sent to anyone interested.

Cheers de Alan G3NYK
Alan.Melia@btinternet.com