ECN Forum Forums General Topics of the Trade Non-US Electrical Systems & Trades "Esoteric" countries and their wiring practices?

I've also seen PAL called "Pictures At Last" and "People Are Lavender". As for the cost of equipment, in the early days of British color (O.K. "Colour" then! ) there were actually two types of PAL decoder used in receivers.

PAL-S was the simple system which just displayed each line as it was decoded and relied upon the human eye to average out any phase error (i.e. a phase shift which would turn a yellow area toward red on one line would automatically shift it toward green on the next line due to the V-signal phase inversion). The PAL-D (Deluxe) decoder used a delay line to electronically average out the phase error before it reached the CRT. And it cost more, of course!


Generally, 625-line PAL gives very good pictures. but then 525-NTSC is capable of excellent results too. I've dealt with all three of the main systems (625-PAL, 625-SECAM, 525-NTSC) and given good clean signals with properly adjusted equipment they are all capable of delivering good quality pictures. In fact, when I was at Goonhilly we would regularly have a bank of monitors displaying images in all three formats and it was very difficult to tell them apart without looking at the telltale mode lights.

In fact in a studio environment, NTSC has some advantages over PAL, such as improved vertical color resolution and the ability to make tighter edits on videotape.

Where PAL scores heavily is under "average" broadcast conditions. NTSC is very sensitive to phase shifts in the color subcarrier, which result in hue errors. That's why American sets have separate hue and saturation controls.

With PAL the color reference oscillator in the receiver is accurately locked to the transmitted signal so that only a saturation control is needed. Thus PAL tends to give better results when the signal is less than ideal, although the difference is perhaps not quite so great as some people would have you believe.

As has been mentioned above, the distribution network for TV signals can do all sorts of nasty things to the signals. Cable TV is common throughout America, but all systems are not equal! I've seen a few cable networks where the quality of the signals is really bad (certainly below FCC minimums for broadcast quality). It takes only a few bad connections on the cables (or one or two unauthorized taps!) to really mess up the impedance matching and create some horrible phase shift errors. PAL and SECAM will also suffer from bad ghosting and other gremlins in such circumstances.

The old French system was actually 819 lines, and was monochrome only. You can't call it SECAM, because SECAM is the color system (Sequentiel Couleur A Memoire), which as you say was adopted in France with a change to 625 line standards.

I've heard various arguments over why France favored SECAM over other systems, including the one that it was to protect French manufacturing interests. Although SECAM wasn't widely transmitted until much later, it was being developed in the 1950s though, and thus pre-dates PAL, at least in its first version. It also went through several stages of development, and today there still exists a variant of "standard SECAM" which is used in some Middle-East countries.

VHS and Beta video formats for PAL and SECAM are different. The basic luminance and sound recording are identical, only the color signals are handled differently, so it's possible to play such a tape in the "wrong" machine and get a black-&-white picture.

By the way, in some circles SECAM is known as "System Essentially Contrary to American Method." Never let it be said that engineers don't have a sense of humor!

Neither have I! I suspect that somewhere along the line somebody might have misread and corrupted this abbreviation from "OIRT". The latter is the official broadcast standard used in many former Eastern-Block countries (I forget what the initials stand for).

Not only did they adopt SECAM rather than PAL for color (which in itself would still have allowed people near the border to watch Western TV in black-&-white), they also used different channel assignments and spacing. A major difference is that system B (most of Western Europe, except France) used 5.5MHz spacing between video and audio carriers whereas system D (Eastern Europe) was 6.5MHz. That would prevent anyone tuning in the "wrong" stations from hearing any sound!


[This message has been edited by pauluk (edited 01-12-2003).]