El 02/01/2012 23:33, Magnus Danielson escribió:
The small TV set in the kitchen might be CRT while the big one in the
living room is LCD (or any similar flat screen), and for the later
double-buffering (or more) is employed as standard. These new screens
are "slow" and create tons of artefact with standard definition TV or
just the wrong rate.
In the transition time between analog and digital TV in Spain, I had an
analog TV at the kitchen and a digital LCD at the living room. Both
transmissions were from the same site, but the audio and video delay in
the digital one with respect to the analog was in the order of two
seconds. I suppose that part is on the TV, but the bigger delay is in
the transmission side :) Now, analog TV is gone, so no opportunity to
repeat the experiment.
Long time ago (~25yr), I had a friend working at Torrespaña, that is the
production and transmission center for the spanish national television,
TVE. Since I was a latent time nut then, I was interested on the
different timing systems, and he show them to me. Time distribution, for
teletext and for the clock that was shown at 3pm and 9pm during a few
seconds just before the news, was taken by a time distribution system
provided by Union Relojera Suiza (Swiss Clockwork Union or something
like that), and I don't remember exactly but I think that the time for
that system was taken from a leased line from ROA (the Real Observatory
of Spain at San Fernando, Cadiz, the official timekeepers and UTC
contributors at Spain), so it was a quite good time. Synchronisms were
generated from a HP 5061 Cs, and chroma burst was generated by a HP 5065
Rb.
Around 7 yr ago, I gave a friend a GPS driven nixie clock, and he had
fun taken a picture in which you can see that the second changes
simultaneously in the TVE teletext clock and the nixie clock (both in
screen and at the clock the second digits were superimposed), so it
seems that the discrepancy is inside an aperture time (probably 1/125 -
he was not using any special technique). He lives 2-3km from Torrespaña,
so the delay due to propagation is in the microsecond range.
From 50yr ago, in Spain a lot of people celebrates the new year with
the TVE transmission of the clock located at Puerta del Sol in Madrid,
in the center of Spain (in fact, Km 0 for the six main radial roads
starting from Madrid), and customarily people takes twelve grapes, one
at each gong of the clock. I know that it is 50yr because this year they
were celebrating the 50 anniversary of the first transmission of the
event :) Now, I know that people celebrates new year with at least 2
second delay thanks to DTV progress :)
(In my case, from long ago, I'm out of Spain for new year, at the place
where the local people celebrates the event - this year, Rathaus
building clock in Vienna :) )
A bit late, but happy new year to all!!!!
Regards,
Javier
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