[time-nuts] Time/freq from digital TV

Alan Melia alan.melia at btinternet.com
Sun Jun 14 08:07:06 EDT 2009

Hi Magnus that may be the case in some countries I suppose. Surely the
accuracy is only required at the  end of the transmission link, the frames
from different sources are then resynchronised, and it is not "necessary" to
transmit nationwide accurately synced frames?? The UK is "privatised" and
content distribution network and transmitters are no longer owned by the
programme companies, and they probably have little say in this aspect except
that it will depend upon the price they are willing to pay.......... hence
the BBC engineer did not think it a "reliable form of frequency distribution
in the UK"....this does not mean it might not be useful!


----- Original Message -----
From: "Magnus Danielson" <magnus at rubidium.dyndns.org>
To: "Discussion of precise time and frequency measurement"
<time-nuts at febo.com>
Sent: Sunday, June 14, 2009 12:31 PM
Subject: Re: [time-nuts] Time/freq from digital TV

> Alan Melia skrev:
> > This may not relate to the USA but a couple of years back I had an
> > interesting chat with a BBC engineer at an NPL Time and Frequency
> > at Teddington. His comment was along the lines of....."....well there is
> > you realise not need to sync lines and frames nationally now because all
> > network content travels digitally even though we have only just started
> > phased change-over. The frames and line syncs broadcast will be probably
> > derived from a "good clock" but it will not be a single traceable unit
as it
> > was. There is no telling how good the clock is, though it will probably
> > better than absolutely necesary.
> Actually, this is still far from the thinking I have heard from other
> sources. They essentially want everything traceable to TAI/UTC.
> Digital doesn't help, it makes it more acute actually.
> Cheers,
> Magnus
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