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What is "special PAL signal" or "ANTI PAL signal"?

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dongtm
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Hi all,

I see in various Sony documentation a term called "special PAL signal" or "Ant Pal signal". It is used to calibrate the color decoder. The signal is supposed to be available from a signal generator (exact model never referenced).

I have a Leader 404 PAL pattern generator. While not the most complicated, it is one of the industry standard machine. Also I don't remember seeing a fuction like special-pal in more expensive generators.

Can someone explain what this signal is, and what generator is known to produce this signal? Thanks!

Attached are waveforms and description shown in service manuals, from PVM9220 and 1440 respectively.

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Guest
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"antiPAL test pattern
A video signal that has a deliberately wrong PAL switch function. The polarity of the U component, instead of the V component, is switched. This enables measuring the performance of the line averaging function in the PAL decoder. When it works correctly, the display has no color since the antiPAL chrominance is cancelled by the decoder’s line averaging."

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http://www.sabadosco.com/wp-content/uploads/2016/01/terminologija4.pdf

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dongtm
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Thanks! That explains perfectly.
One question remains open: which generator is known to generate antiPAL?
Sounds like it could be done by messing/modding with some 74LSxxx inside the existing generator. Wonder if service stations would receive instruction for such mods back in the days.

@ Josef
Sorry but Pal-plus is another story. It's more like PAL in 16:9 non-HD, still used widely in Europe by local cable providers for those who don't pay for digital services.

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Guest
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Example from another generator Leader399

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dongtm
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Thanks! this info is very, very helpful.
It turned out my 404 is actually a 399 with an addon SECAM module. Board reference and PN are exact matched.
Looking at this diagram I thought these 74s must be added by user, but they are already in placelaugh The color bar program is switchable with a factory-installed DIP set marked 555x. Wonder why Leader didn't make it more user accessable.

(Edit: the result of flipping the switch: top half frame in normal color bar, bottom half in grey antiPAL. Strangely no option to display full-screen anti-PAL. Should be fine anyway.)

Now we can say case closed.

BTW with my further research there are indeed more advanced generators available to generate Special PAL with front control. For example, Shibasoku TG19. Maybe that's what the Sony manuals referred to. But you can tell that thing is in a different league, must be really rare and expensive.

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josef.48
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Hallo !      probably .... https://en.wikipedia.org/wiki/PALplus

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