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The
rate of recombination of the E (?) layer causing the height to change at
dusk / dawn will move at this sort of rate.
I did
see Doppler shifts, although not perhaps quite as great as this, on the signals
from Larry at least once. This is one of the mechanisms limiting the data
rates we can go down to when using very low signalling
rates.
A
couple of years ago I made some tests receiving DCF, the German time
signal, comparing its phase against a locally generated Caesium
reference. The interference patterns at dusk / dawn showed fading
consistent with interference between the two skywave & groundwave
signals, one of which was changing at a rate consistent with this order of
magnitude of velocity.
Andy G4JNT
Dear all.
I have the Argo screen-shots of ZL6QH recorded in
Papua New Guinea, a path of about 4,700km. This is not very different from out
trans-Atlantic tests but Ricks traces show a Doppler effect around midnight
which spreads the signal over about 0.1Hz, I have never seen this on a
136k trans-Atlantic trace.
Rick has calculated that the reflecting medium
would have to have a velocity of around 100m/sec, assuming a double hop, to
cause this kind of shift.
Any propagation brains care to speculate on the
cause of this, and is there a reason why we haven't seen it on
136?
73.
Dave.
G3YXM
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