Message-ID: <005c01c0767e$ffaa94a0$05b21bca@xtr743187>
From: "Vernall" <vernall@xtra.co.nz>
To: rsgb_lf_group@blacksheep.org
References: <98.ec1517f.27851f1b@aol.com> <000801c075fb$20171a80$66b51bca@xtr743187> <3A545A59.323AC1AD@usa.net>
Subject: LF: Re: RE: Freq stability
Date: Fri, 5 Jan 2001 07:46:48 +1300
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Alberto,

> Vernall wrote:
> > The TVNZ nationwide network, with two Tv channels, has a Rubidium source
for
> > timing.
>
> In Italy, the state-owned TV broadcaster RAI has all its timings locked to
a central
> Caesium standard, in Rome. Or at least so I have been told by a former RAI
employee.
> I'm wondering if some simple circuit diagram is to be found somewhere, to
receive and
> recover the synch timings, without using a real TV, bulky and noisy.
>
> 73
> Alberto    I2PHD

Alberto,

The relatively simple circuits I am aware of need a good quality composite
video signal to start with, then use line synch pulses to phase lock a local
10 MHz oscillator.  There was a circuit in Radcom a couple of years back,
which seemed to be very similar to an Electronics Australia project from
1993.

The composite video could come from a VCR rather than a TV set.  Running an
actual TV set in the shack would generally be shooting oneself in the foot
for LF QRM :-(   Also you likely need much better than a piece of wet string
for the TV antenna, as noise or ghosting on the received video will not
result in a lab standard for the reference signal.

73, Bob