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Paul, thanks for this work!
> and
carrier would be sqrt(2) times stronger than opera.
I think the difference between 100% carrier and
50% keyed Opera is actually 6 dB, because the central spectral peak
is a voltage integral. In terms of power, on average 50% power is used. 25%
goes to the carrier and other 25% into the modulation
sidebands.
73, Markus
Sent: Monday, March 10, 2014 11:07 PM
Subject: Re: LF: Daytime 29.499 kHz
A
better signal last night from WH2XBA/1 and I was able to go
back to using 10
minute averages to improve time resolution
http://abelian.org/vlf/tmp/29499_140310a.gif
120
deg phase change as usual but taking till 04:00 to complete.
S/N here was
good between 04:00 and 08:00 thanks to background
subsiding.
Now four
days comparison with NAA
http://abelian.org/vlf/tmp/29499_140310b.gif
The
first 3 nights were opera but last night was carrier until
04:00 and carrier
would be sqrt(2) times stronger than opera.
Yes it is possible for winter
day maximum to exceed that
of summer on certain paths. There is no
simple rule to say
which path.
For example DHO at 23.4kHz to Todmorden
(646 km)
http://abelian.org/vlf/tmp/dho_2013a.png
http://abelian.org/vlf/tmp/dho_2012a.png
Propagation
is complicated at short range because there are
many modes (or combinations
of rays with different number
of hops if you visualise things that way)
contributing to the
total signal. When calculating signals by ray
tracing it is
usually necessary to include paths with up to 12 or 15
hops
at least, in order to get a model that resembles a real
diurnal.
--
Paul Nicholson
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