[time-nuts] Time/freq from digital TV

Magnus Danielson magnus at rubidium.dyndns.org
Sun Jun 14 08:41:34 EDT 2009


Hi Alan,

Alan Melia wrote:
> 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!
>   
Already in the production phase over contribution networks, avoiding 
frame stores is what you want. In one example a feed across Europe 
included 4 frame stores.

As for SFN networks, from the SFN adapter you want propper timing to all 
receivers and SFN adapters. If you have one mux being national, that mux 
needs the good timing throughout the whole national network, unless you 
ignore SFN properties in some areas.

You don't framestore in the distribution phase, it's already encoded and 
everything.

The flat TV screens people now have also include frame stores, causing 
headaches...

I'll stick to my fatscreen a little while longer. Framestores should 
only be used with care, they solve stupid problems but lowers the quality.

Anyway, the assumption that timing is being fucked up locally with DTV 
is just not necesserilly correct. In the SFN world it is quite the 
opposite actually.

However, the development has enabled lower and lower achieved qualities 
to be accepted, while everyone has had to invest again. Great deal, 
isn't it?

Cheers,
Magnus




More information about the time-nuts mailing list