From G3PLX;
Alan G3NYK gave some idea of how stable Droitwich 198kHz might be. I had the
chance to leave my GPS-locked system monitoring it over most of a day. The
results may be of interest.
During the daytime, the maximum phase excursion I saw was 10 degrees peak to
peak. The largest change seen over the 5-minute sample interval was 4
degrees, corresponding to a worst-case apparent frequency error of 37uHz.
At night there was evidence of skywave, which showed as three cycles of
phase-change extending over 30 degrees peak-to-peak between 21:45z and
01:30z. The largest change seen over 5 minutes was 22 degrees, corresponding
to a frequency error of 200uHz. A quick calculation from this says the
skywave was about 12dB down on the groundwave at it's strongest in the
middle of the night. The worst disturbance was in the middle of the night,
not at sunrise or sunset.
I am 230km from Droitwich.
73
Peter
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