Text 32071, 76 rader
Skriven 2009-05-04 11:06:45 av Michiel van der Vlist (2:280/5555)
     Kommentar till en text av Robert Bashe (2:2448/44)
Ärende: TV Systems
==================
Hello Bob,

On Monday May 04 2009 08:05, you wrote to Ward Dossche:

 WD>> TV was first introduced in Europe by the BBC with a 625 lines
 WD>> system. The whole of Europe copied it with some minor exceptions.

 RB> New to me - my understanding was that PAL (the 625 line system) was
 RB> developed in Germany.

PAL was indeed developed in Germany. It's father was Dr. Walter Bruch of
Telefunken lab.

But you and Ward are talking apples and oranges. Ward was referring to the
black and white systems in use before the emergence of colour TV. PAL is the
system to add colour to the existing B/W systems.

 WD>> When TV was introduced in France they used an incompatible system
 WD>> of 819 lines ... because of the more lines picture quality was way
 WD>> better than 625.

 RB> Doubtless, for the same reason that PAL gives a better picture than
 RB> NTSC.

No, for the same reason that a 1024x768 monitor gives a better picture than a
640x480 monitor. More pixels...

Note that the video bandwidth of the old French 819 line system is double that
of the German 625 line system. 10 MHz vs 5 MHz. 10 MHz was hard to do with the
technology of that time and that made it expensive.

Also, onoy half as many channels could fit into the spectrum assigned for
broadcasting. Abnd frequecy space always was scrace. That plus the cost was
probably the reason the system was eventually abandonned.

 WD>> Our TV-set, bulky and heavy; had a special knob to switch between
 WD>> 625 and 819.

 RB> Never seen or even heard of anything like that.

It was even worse. Although the Flmish used s 625 system, it was different from
the 625 line system used in Germany and The Netherlands. (Positive vs negative
video modulation). So people who wanted to be able to see the Dutch/german TV
and the Flamish TV and the Wallon TV, nede a 3 system receiver. They existed,
but they were exensive and bulky..

 WD>> SECAM was about colour-TV technology, that's another subject.

 RB> How so? The lines per screen is part of the system.

Not really. NTSC. PAL en SECAM are *additions* to exsting B/W systems. One can
add either NTSC, PAL or SECAM to B?W systems with any number of lines. With
different frequencies for the colour subcarrier of course.

My TV can do both 615 line PAL and 625 line NTSC. selection is automatic.

 RB> But SECAM couldn't have been this 819-line stuff, as a PAL set could
 RB> receive it, but the picture was in black and white

That is because in the meantime they had dropped the 819 line system in favour
of 625 lines. In theory however one could have a 819 line SECAM system. Don't
think it ever was implemented though.

 RB>  - the color information wasn't used except in sets equipped for
 RB> reception of both types of signal (formerly popular in areas close to
 RB> the GDR).

And among camper/caravan owners...

With DVB-T those problems are of the past. DVB-T is a European norm and so with
my DVB-T box and TV with scart input I can see TV all over Europe.

Cheers, Michiel

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