Does ZDF still make use of TV sync to distribute standard time and frequency in
Germany ? This signal received from Astra could be relied on as being highly
accurate when this was the case and several microwave operators built TV locked
local oscillators for 10s of Hz accuracy at 24 GHz plus.
Not sure if the Doppler shift due to orbital wobble will affect the modulation
in the same way it does carrier frequency. Are there any physicists out there
who can confirm this ?
Andy G4JNT
-----Original Message-----
From: Alberto di Bene [SMTP:[email protected]]
Sent: 2002/04/16 10:02
To: [email protected]
Subject: Re: LF: Phase meter for propagation experiment
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
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