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Hi Markus I did not spend a lot of time on day-time
analysis but over one year (DCF39 to Porto) I did see anout 5dB better noon
signal in summer than winter. I also found some connection with electron
precipitation. Daytime sigs can be much enhanced after a major geomag storm, but
I did think there was evidence on Lakihegi of an effect at lower storm levels. I
did not continue these tests after a power outage stopped the logging.....about
6 weeks data around September. The differences were around the same level as the
normal "wriggling" of the graph line. The day after the storm yielded slightly
better levels, but this could have been "phasing effects"
Alan
----- Original Message -----
Sent: Thursday, June 26, 2014 10:27
PM
Subject: Re: LF: Re: RE: Summer Solstice
Test report
Yes Alan, I also think the "dome", due to
strongest D-layer ionisation around local noon, is the essence
of good daytime skywave LF and VLF propagation.
Loran-C observations seem to show that though the
maximum is much shorter during the winter season, it is not necessarily
weaker. I wonder whether increased sunlight intensity during January
earth perihel might somewhat counteract lower solar elevation... If so,
Southern latitudes should experience significantly stronger daytime
propagation during their summer than we do in ours.
73, Markus
(DF6NM)
Sent: Thursday, June 26, 2014 3:08 PM
Subject: LF: Re: RE: Summer Solstice Test report
Hi Mike well at 137 the daytime signal is
skywave over about 700km I
watched Budapest (about 1200km) and there is a
distinct "dome" in the
response at local noon at mid path. This is higher
in summer as the sun is
higher and so stronger. I think on 472 the
ground-wave is shorter
particularly at our power and aerial situations,
and I suspect the skywave
though there may not be as predominant as at
137. .....more day-time
absorption. I am sure the local environment, trees
building etc has an
effect too.
Alan
----- Original Message
-----
From: "Mike Dennison" <[email protected]>
To:
<[email protected]>;
<[email protected]>
Sent:
Thursday, June 26, 2014 12:43 PM
Subject: LF: RE: Summer Solstice Test
report
> On 25 Jun 2014 at 21:55, Alan Melia
wrote:
>>
>> It is interesting that there does seem to be a
suggestion that 137
>> holds up better in summer than 472.......have
I read that correctly,
>> or maybe it was from another poster. I was
not able to do the same
>> sort of tests for
472.
>
>
> I haven't done any scientific tests, but from a
lot of monitoring it
> seems that for daytime ranges around 500-1000km
136kHz works better
> than 472kHz. I presume this because the 136kHz
daytime propagation
> over this distance is primarily by ground wave,
whereas on 472kHz the
> ground wave range is less so sky-wave is needed
and this is not
> available until dusk.
>
> It is difficult
to compare the two bands over longer distances
> because 472kHz is not
available in Russia (unlike 136kHz), and
> activity seems low in many
other countries.
>
> Personally, I have been disappointed by the
amount of DX received
> during darkness hours on 472kHz so far. It seems
commonplace
> to receive stations out to Scandinavia and Italy, but
little beyond.
> Yes, I have seen some transatlantic DX but nothing to
match
> the stories of worldwide openings reported by retired marine
500kHz
> operators, or indeed what is availalable routinely on 160m. Is
this
> just lack of activity?
>
> de Mike, G3XDV
>
============
>
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