NTSC versus PAL

I would guess that you never would see such an effect, as all of the decoders that I can remember working on, had ACC circuits which worked very well ...

Arfa

This was first done by GE, circa 1966, in the Portacolor set, mostly because it was cheaper.

Another way of looking at this system is that the crystal was an extremely narrow-band filter that removed the "Fourier sidebands" around the subcarrier frequency created by transmitting the 10-cycle burst only once on each scanning line.

It is, for people who consider one as zero.

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.

--snippety-snip--

Political. The Europeans didn't want US companies selling sets there.

Isaac

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.

Correct.

Also correct.

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

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.

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.

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!

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

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?

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.

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.

You're probably correct.

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.

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 ;)

Poor convergence? The mind boggles.

Sylvia.

And AT&T who provided the coaxial cables that fed the video to all the stations on a network. The tint and chroma level could be adjusted at every facility in the system. I knew someone who worked for AT&T at the time, and he told me what a pain it was to compensate for the cable. When the network switched to a different studio or city for a show, it threw everything out of calibration.

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. Some TVs still had hollow plastic shaft extenders that passed through the rear of floor model cabinets to adjust these and other pots.

The fourth would be the actual dolor intensity control.

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.

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

So camera setup was poor - as was the later stages of transmission?

This certainly wasn't the case in the UK - despite the transmitters being fed with land lines.