NTSC versus PAL

[William Sommerwerck]

I'm left wondering what exactly was the *real* problem that PAL

was intended to fix. It appears that the NTSC tint control could
only address a fixed phase offset between the colour burst and
the subcarrier, with both transmitters and TV sets able to
maintain that offset sufficiently closely that the hue wouldn't
vary from left to right of the picture.
Correct.


Other issues, such as non-linear phase shift would have been
a problem for NTSC viewers, regardless of the tint control.

Also correct.

So were NTSC viewers tolerating colour pictures that couldn't
be set right even with the tint control? Or is there something
else that I've missed?

You /have/ missed something, which I explained "long ago and far away".
<grin>

The US TV-distribution system DID NOT generally suffer from non-linear
group-delay problems, whereas the European system DID. That's it.

Even without the extra delay line, there is some degree of visual color
averaging, which tends to mitigate the phase error.

 

[William Sommerwerck]

Political. The Europeans didn't want US companies selling

Didn't stop the Japanese, etc. But US companies would have
to do other mods to their products for European sales anyway.
Like mains voltage and frequency. Most couldn't be bothered --
even when that's all which had to be changed.

I don't buy that. US sets would have been fairly expensive in Europe, even
in the mid-60s. Not to mention the strong competition from Thomson, Philips,
etc.

 

[PeterD]

I'm left wondering what exactly was the *real* problem that PAL was
intended to fix. It appears that the NTSC tint control could only
address a fixed phase offset between the colour burst and the
subcarrier, with both transmitters and TV sets able to maintain that
offset sufficiently closely that the hue wouldn't vary from left to
right of the picture.

Other issues, such as non-linear phase shift would have been a problem
for NTSC viewers, regardless of the tint control.

So were NTSC viewers tolerating colour pictures that couldn't be set
right even with the tint control? Or is there something else that I've
missed?

Sylvia.

Part of the difficulity in understanding is that perhaps you don't
have experience with early American color televisions... I certainly
remember how in the 60s we had to adjust the tint control on a regular
(show by show) basis, because of lack of consistancy.

Today, with predominatly digital systems, it has been so long since
I've touched a tint control, that I wonder if they still exist!

Anyone who had one of those old, tube (valve) color sets, with the 21"
round color CRT, will remember seeing green skies, and blue grass
while having skin colors set to the proper shade. Get the sky blue,
and the skin turned red, or blue, or green!

 

[William Sommerwerck]

Part of the difficulity in understanding is that perhaps you

don't have experience with early American color televisions...
I certainly remember how in the 60s we had to adjust the tint
control on a regular (show by show) basis, because of lack
of consistancy.

Yes -- a lack of consistency. That was not the fault of NTSC, but of the
broadcasters.

Anyone who had one of those old, tube (valve) color sets,
with the 21" round color CRT, will remember seeing green
skies, and blue grass while having skin colors set to the
proper shade. Get the sky blue, and the skin turned red,
or blue, or green!

I don't think that's correct. The cameras (and/or encoders) would have had
to have been very badly set up for that to happen.


On a related subject... I remember reading long, long ago that the first RCA
color TV had /four/ controls for adjusting the color, which the author
described as a "combination lock"! Anyone know anything about this?

 

[Sylvia Else]

Also correct.



You /have/ missed something, which I explained "long ago and far away".
<grin>

OK, I vaguely remember your saying that now.

In the UK, colour was only transmitted on a new 625 line service
(newish, in the case of BBC2), in parallel for a long time with a
monochrome 405 line service (except BBC2), and I'd have thought the new
transmission infrastructure could have been built to obviate the
non-linear group-delay, given that it existed in the USA.

And, as I commented before, the Sony Trinitron sets, which didn't
implement PAL, performed acceptably according to my memory.

Sylvia.

 

[Sylvia Else]

Yes -- a lack of consistency. That was not the fault of NTSC, but of the
broadcasters.

I have to wonder what the broadcasters were doing to achieve that.
Contriving to get the colour burst phase consistent amongst cameras in a
studio (so that the tint stayed the same for a show), but inconsistent
with the actual colour subcarrier, would take some doing.

Sylvia.

 

[William Sommerwerck]

In the UK, colour was only transmitted on a new 625-line

service (newish, in the case of BBC2), in parallel for a long
time with a monochrome 405 line service (except BBC2),
and I'd have thought the new transmission infrastructure
could have been built to obviate the non-linear group-delay,
given that it existed in the USA.

You're probably correct.

 

[William Sommerwerck]

Yes -- a lack of consistency. That was not the fault

I have to wonder what the broadcasters were doing to achieve
that. Contriving to get the colour burst phase consistent amongst
cameras in a studio (so that the tint stayed the same for a show),
but inconsistent with the actual colour subcarrier, would take
some doing.

There is no subcarrier or burst signal in the cameras. They aren't needed at
that point, and are added during the encoding process.

Setting them up is another matter. The early episodes of "Barney Miller"
provide a good example of poor setup, with inconsistent color, and poor
convergence.

 

[Sylvia Else]

There is no subcarrier or burst signal in the cameras. They aren't needed at
that point, and are added during the encoding process.

Ok, so the separate colour signals (and luminance?) are sent from the
cameras. Still, at some point the colour signals have to be encoded
using the colour subcarrier, and a bit of the latter has to be included
as the burst. Failing to keep them in phase would require a considerable
amount of indifference.

Which I think you've also said

Setting them up is another matter. The early episodes of "Barney Miller"
provide a good example of poor setup, with inconsistent color, and poor
convergence.

Poor convergence? The mind boggles.

Sylvia.

 

[William Sommerwerck]

Setting them up is another matter. The early episodes of

Poor convergence? The mind boggles.

Oh, yes. The pickups had to be aligned. The "modern" system, in which
solid-state sensors are attached to a prism/beamsplitter was not practical
with vidicons and Plumbicons.

 

[William Sommerwerck]

On a related subject... I remember reading long, long ago

He may be talking about the three 'drive' controls that set the
gain for each channel. These are set up to provide equal gain
to get a white line during setup. They are service adjustments
on TVs, but on an early design they may have been easier to get to.

No, these were supposedly user controls. Anybody got a photo of the user
controls for a CT-100?

 

[William Sommerwerck]

Registration on cameras. Convergence on monitors?

Yes. Thanks for the correction.

Did you have videcon colour cameras? First UK ones
were Plumbicon.

Yes, because you started so late.

The first RCA cameras used vidicons (I think) -- though they might have used
image orhticons.

They later had a four-pickup camera that used an image orthicon to generate
a perfectly registered (by definition) luminance signal, plus three
vidicons.