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Old December 4th 16, 07:41 PM posted to uk.tech.digital-tv
Roderick Stewart[_3_]
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Posts: 2,246
Default Digital drop out.

On Sun, 04 Dec 2016 16:21:34 +0000 (GMT), Jim Lesurf
wrote:

As I understand it, it is delays due to the processing of the digital
signal. Different sets may have different delays, and radio and TV may
have even more different delays. FM radio would have given you Big Ben
accurately, but nothing digital is likely to have done.


Strictly speaking FM uses NICAM for distribution, and NICAM is "digital".
It does add a delay, but I doubt you'd notice it. So your "nothing" aims at
the wrong target. The cause is the lossy compression schemes employed for
'digital' TV and radio which the systems take some time to process. Not
"digital" per se.


Presumably the compression for video takes considerably longer than
for audio, but the audio part of a television broadcast has to be
delayed to match the picture. Audio on its own, i.e. radio, wouldn't
need so much so the delay wouldn't be noticeable.

I first became aware of how much delay must be in the system on the
day of Princess Diana's funeral, when every channel (except 4) was
broadcasting the same material, and the difference between the latest
and earliest version was about 8 seconds. The only time you can trust
is either a radio controlled clock or the internet. Broadcasting used
to be an authoritative source for everything but not any more.

Rod.
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