[time-nuts] WWV Doppler Shift

[Donald E. Pauly]

HF propagation of WWV or WWVH is horrible compared to VLF propagation
of WWVB at 60 kc.  In this video the 5 mc WWV signal from Ft Collins,
Colorado is being received in New Jersey.  It was compared against a
stable 5mc crystal source.  You can see a shift of a few cycles per
second over a few seconds.  This is due to the movement up or down of
the ionosphere at a substantial fraction of the speed of sound. I
understand that it can be as bad as a part per million short term at
some frequencies.  The 10 mc and 15 mc broadcasts may be better or
worse at various times of day.

I have spent many hours watching WWVB in the days when they had the
old format.  It was good to a part per billion except just before
sunrise and just after sunset.  Then it degraded to either + or -5
parts per billion for about 30 minutes.

https://www.youtube.com/watch?v=nf9KWfS9QBs