Re: LF: Daytime 29.499 kHz

[Paul Nicholson <vlf0403@abelian.org>]

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
--