SECAM and PAL

[ppppenguin]

I wanted to pick the SECAm vs PAL theme from this thread:

https://www.vintage-radio.net/forum/...ead.php?t=9777

PAL was derived from the American NTSC system and addressed the problems caused by differential gain and phase distortions in the transmision path. Dr Bruch at Telefunken built on the colour phase alternation work done at Hazeltine labs in the late 1940s.

SECAM (sometimes unkindly called System Essentially Contrary to the American Method) was developed by Henri de France and his team. It addressed the same problems as PAL but in a very different way.

SECAM was good for long transmission networks and early VTRs since the FM colour system was very rugged. This influenced the USSR's decision to go SECAM since they had very long distribution networks and did not have acccess to the latest American colour VTR technology.

It was soon realised that SECAM was a liability for programme production. You cannot fade or mix a SECAM signal since the colour is FM. I worked for a company that made SECAM vision mixers and they were a horrible kludge. In practice the French soon started making programmes in PAL and transcoded to SECAM for transmission. It's hardly surprising that the French were very enthusiastic about programme production using component video which translates equally well to PAL or SECAM. The Eastern European countries took a more purist line on SECAM. I remember SECAM vision mixers being built for the Moscow Olympics and the Bulgarians coming over to do acceptance tests on SECAM mixers.

The 50Hz world polarised into PAL and SECAM camps, depending on where the French had influence at the time. The US and Japan styaed with NTSC and a few south American countries used odd variants of PAL.

There's not a lot wrong with well engineered NTSC but this wasn't easy in the 1950s or even 1960s so there were strong arguments for PAL and SECAM.

This can only be a brief introduction to the battle of the colour systems. There was a lot of heated argument at the time. Now it's all history. All new TV distribution methods are based on colour components.

[johnmarshmanagain]

Thanks to J for lucid explanation. What is the "colour components" technique mentioned ? Do you simply mean that the three colours are kept separate for as long as poss before transmission ?
Ta J

[ppppenguin]

All sources of colour signals originate them, at least conceptually, as RGB components. These are transformed to YPbPr components' often incorrectly called YUV but the usage has stuck. This gives a full bandwidth monochrome picture (Y) and 2 colour difference components, usually with reduced bandwidth. The important point about component is that the signals are never combined in a way that isn't full separable. Modern transmission methods may add their own problems (blockiness, mosquito noise etc) but the old NTSC, PAL and SECAM distortions are eliminated.

[murphyv310]

I only saw SECAM pictures a few times a good number of years ago and I was really impressed looked a lot better than PAL.
Trevor

[paulsherwin]

I think that in a domestic environment PAL, SECAM and modern NTSC are effectively indistinguishable. Some Americans do claim to see objectionable flicker on 50Hz systems though - I suppose it's just what your brain gets used to.

Paul