Message-ID: <01C1E536.029E0670.g4jnt@thersgb.net>
From: "Andy talbot" <g4jnt@thersgb.net>
To: rsgb_lf_group@blacksheep.org
Subject: RE: LF: Phase meter for propagation experiment
Date: Tue, 16 Apr 2002 11:01:00 +0100
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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:dibene@usa.net]
Sent:	2002/04/16 10:02
To:	rsgb_lf_group@blacksheep.org
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