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PAL/NTSC - chroma phase vs. colour documentation

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Rob
Guest

Wed Mar 18, 2020 9:45 pm   



Silver Dream ! <email_at_domain.com> wrote:
Quote:
It was better in terms of colour fidelity and resolution. It was worse
in terms of flickering, due to lower refresh rate and some el cheapo
decoders being employed too often.


The refresh rate has nothing to do with the color standard (NTSC vs PAL),
it is because of the different mains frequency in the countries that used
the standard, and the advantage of approximately synchronizing the vertical
refresh with the mains frequency on older receivers.

In Brazil, PAL is (was) used with the same refresh rate as was used
for NTSC in the USA.

Rob
Guest

Wed Mar 18, 2020 9:45 pm   



Jeff Urban <jurb6006_at_gmail.com> wrote:
> From what I've read PAL is very similar to NTSC. It has a scheme with a comb filter that makes a phase (tint) control unnecessary, 50Hz frame rate rather than 60 and a higher horizontal rate resulting in more lines in the raster. (your spelling says you are across the pond)

The different frame rate is not an attribute of PAL vs NTSC, but of the
underlying B/W standard that was optimized for the local mains frequency.

PAL is used with ~60Hz frame rate in Brazil. NTSC with 50 Hz frame rate
is possible, but there just happened to be no country where a 50 Hz mains
frequency was in use and where NTSC color was selected.

Phil Allison
Guest

Wed Mar 18, 2020 11:45 pm   



Rob wrote:
--------------

Quote:

The refresh rate has nothing to do with the color standard (NTSC vs PAL),
it is because of the different mains frequency in the countries that used
the standard, and the advantage of approximately synchronizing the vertical refresh with the mains frequency on older receivers.



** Early tube based ( B&W ) receivers were locked to the supply frequency as were the local TV transmitters. This simplified PSU design and prevented hum bars rolling down the screen. Later this was changed to non locked.

60Hz was had an inherent problem cos it conflicted with frames rates used by film cameras. 50 Hz was far better since is was close to double the 24 fps rate used for movies - so on TV they ran slightly faster than in a cinemas.

60Hz TV has to use tricks (repeated frames) to play 24fps movies and can look jerky - even today.


..... Phil

Silver Dream !
Guest

Thu Mar 19, 2020 10:45 am   



On 2020-03-18 19:56:39 +0000, Rob said:

Quote:
It was better in terms of colour fidelity and resolution. It was worse
in terms of flickering, due to lower refresh rate and some el cheapo
decoders being employed too often.

The refresh rate has nothing to do with the color standard (NTSC vs PAL),
it is because of the different mains frequency in the countries that used
the standard, and the advantage of approximately synchronizing the vertical
refresh with the mains frequency on older receivers.


True - refresh rate is defined in other standards, which define also
number of lines.

see Rec. ITU-R BT.470-6 p. 2
That was an inaccurate mental shortcut from my side. Caused by the fact
that I live on the other side of the pond, where "M" norm (525/60) you
refer to wasn't used. OTOH NTSC isn't used with anything else than "M".
This opens the trap I fell into and inaccurately combined PAL
characteristics with non-M refresh rate/resolution, even if I myself
corrected other people on occasions before.


Quote:
In Brazil, PAL is (was) used with the same refresh rate as was used
for NTSC in the USA.


Right - PAL/M

--
SD!

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