In article ,
Geoffrey S. Mendelson wrote:
But I don't think that's correct. For it to work, TV would have to be
mains locked. It was in the very early days, but later was pulse
generator locked with no direct reference to mains other than being
nominally the same frequency. Mains lock was really just to make
receiver design simpler.

You sort of danced around it. In the very early days is when the
frequency was set. Once set it stayed.

Sadly not when locked to mains as that frequency drifts. By rather a lot
in electronic terms.

That really was the point of my very long explanation. A long time ago
someone decided to fix the scan rate and representation of data. The
actual information used in all the TV systems was the same, it was just
used with incompatable frame rates, encoding systems and transmission
systems mostly for politcal reasons. TV sets that could receive, decode
and play any and all signals existed.

I think you're reading in the political bit. Different countries had
settled on different mains frequencies rather before such things mattered
much.

The reason that everyone did not have a universal TV set was because the
price was kept lower with single system sets and countries like the UK,
which made a substansial income from the TV license did not want you
watching tv from France or the Republic of Ireland for free.

That is total nonsense. The TV licence is needed in the UK just to
operated a TV receiver - regardless of where the progs are transmitted
from. And they were single channel sets originally, because only the BBC
transmitted TV and only the one channel. Not many in the UK would have
been interested in French language broadcasts. ;-)

From a technology point of view, it was obvious that the digitial TV
standards MPEG and so on were designed with existing TV sets in mind. If
not they would not have been a continuation of the old limited national
standards with their horrible color encoding choice (1/4 of the
resolution that the monochrome signal had) and instead gone with the
more extensible, accurate and easily compressable RGB system used in
computer data.

Think you're well into hindsight. When the UK PAL system was finalised
(1960?), computers were some esoteric device in a lab. But in any case a
major priority of any colour TV system then was that it can be easily
receivable on a monochrome only set - and not make that set more expensive
to produce.

--
*There are two sides to every divorce: Yours and **** head's*

Dave Plowman London SW
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