Stewart Bryant wrote:

[...]
Thus the phase measurements must be made wrt an analogue
TV transmission.
[...]

What about analogue TV via Astra satellite ? There are dozens of
analogue channels on this bird, and I am told some of them have
very precise synch pulses.
Would the relaying through satellite spoil their precision ? The satellites,
while geostationary, are not exactly at a relative rest wrt the earth.
They are wandering back and forth, with the small onboard jets correcting
this movement. I don't have enough info on the rate of change of their
speed to be able to evaluate the amount of the Doppler effect.

73  Alberto  I2PHD