But the diurnal phase shifts at VLF are predictable and largely
repeatable. Ignore the phase at night and use only the phase records
during the day when an all-daylight propagation path exists. You
might have to "correct" the absolute phase reading by some multiple of
the RF period, but with a low rate of local standard oscillator drift,
this is a simple matter of arithmetic. Back in the day, I managed
Sulzer crystal oscillators at 5 field sites from my office and could
maintain phase continuity for weeks at a time, until we had to diddle
the dial on one or several of them to correct for crystal aging. Then
it was just more arithmetic again. Several of the oscillators had
such low drift rates that all I needed was one daily phase reading
from the VLF phase tracking receiver (Tracor 599Js) at those sites to
know the frequency of the Sulzers there.
... Martin VE3OAT
On Thu, 30 Aug 2018 12:27:12 -0400
Bob kb8tq<kb...@n1k.org> wrote:
WWVB as transmitted ( = right at the input to the antenna) is a wonderfully
stable signal. As soon as
that signal hits the real world things start to degrade. Propagation between
transmit and receive sites
is a big deal, even at 60 KHz. On top of that, there is a*lot* of manmade
noise at 60 KHz. The receive
signal to noise will never be as good as you might like it to be ?.
> I don't know about WWVB, but for DCF77 it's known that sunrise/sunset
causes a phase shift of several 100?s at even moderate distances
(like ~500km). Unfortunately I don't have any measurements at hand.
Attila Kinali
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