Dear LF Group,
Thinking a little more on this idea, it seems to me that using LF standard
frequency signals as a phase reference has a basic flaw - the reference
phase signal received at the stations taking part in the experiment will
also be affected by LF propagation phenomena - there would be no easy way
of separating the effects of propagation on the signal being studied from
propagation effects on the reference signal. So it would seem to be
essential to use a reference signal independent of LF propagation effects,
such as GPS or the TV line timebase.
Thanks to DJ8WX for the LF broadcast info - looking at the Droitwich signal
with my vectorscope circuit some time ago, the 198kHz carrier appears to be
phase modulated, but the phase deviation is only a few 10s of degrees; the
carrier phase just wobbles around a mean value, which would not matter much
in a measurement integrated over several seconds. Some of the other
European broadcast stations have similar phase modulation.
Cheers, Jim Moritz
73 de M0BMU
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