Message-ID: <1256814917.4ae97945334b3@imp.netikka.net>
Date: Thu, 29 Oct 2009 13:15:17 +0200
From: Paul-Henrik <phl@netikka.fi>
To: rsgb_lf_group@blacksheep.org
References: <BLU146-DS47926F17E22E4A73A847ACFB70@phx.gbl> <20091029094436.8EFF831E702@smtps01.kuleuven.be>
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Subject: Re: LF: 500kHz propagation
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Hello Rik, LF!

This shows great similarities to some studies and tests I did together wit=
h
GM4SLV (Shetland Islands) and GI4DPE (Derry, NI) around the same time of=
 year
during the past years.

We called this phenomenon "early propagation". It usually started with wea=
k
fluttery signals that grew rapidly. Peak signals were very strong consider=
ing
mid-path was still well in daylight. After a period of good "early propaga=
tion"
signals generally became very unstable and weaker, often disappeared compl=
etely
until "normal" propagation in darkness took over.

This happened almost as a rule over the path Shetland - Vaasa (1100kms),=
 but not
Derry - Vaasa (1800kms). Derry - Vaasa came alive only after midpath darkn=
ess.

This was before the introduction of WSPR using normal CW-beaconing so abso=
lute
signals levels are unknown. Tests were mostly conducted as "skeds" and
sometimes I ran a mp3-server with my receiver audio on the www so that the
transmitting parties could monitor their own signals almost in real-time=
 (delay
of 5-10 seconds) while the receiving station was unattended.

Thanks for sharing your findings on this phenomenon, very interesting with=
 more
new input.

BR

Paul-Henrik, OH1LSQ

Quoting Rik Strobbe <rik.strobbe@fys.kuleuven.be>:

> Over the past days I monitored the G4JNT WSPR beacon 24/24.
> During daytime I have a weak but consistent copy of Andy's signal,
> average -24dB with ups and down of some dB.
> During nighttime the signal is -10dB on average, with the usual deep
> QSB (peaking -1dB, dips down to -20dB).
> But the most interesting observation is that in the afternoon the
> first peaks (from -24dB up to -8dB) occur as early as 15:45 UTC.
> This is almost 1 hour before sunset (16:37 UTC) and almost 1.5 hours
> before the D-layer (at mid point) goes into darkness.
>
> 73, Rik  ON7YD - OR7T
>
>
>