Who invented PAL?

[yagosaga]

Hi folks,

Does somebody here know that the PAL color system was not invented by Walter Bruch but by the American engineer Bernard Loughlin. Loughlin invented the "Color Phase Alternation" in 1951. The phase of the color carrier was switched every new line or frame, and the phase shift was annihilated in the eye of the beholder.

In case of large phase shifts, a strong flicker appeared on the screen (with frame swichting) or a jalousie effect with line switching. Loughlin’s patent #928474 was accepted 1952 in Germany. The patent expired in 1960. The French engineer Gérard Melchior got a French PAL patent #889835 in 1962. Walter Bruch’s attempts to get a PAL patent were unsuccessful due to the former American and French PAL patents.

Meanwhile, SECAM was established in France, and Bruch took the idea of an acoustic 64 uS delay line from SECAM, and integrated this idea in Loughlin’s invention. Bruch run another attempt to get a patent for the PAL color system. But the patent office accepted only a patent for using a delay line in the color television receiver. More curious: Bruch’s unique color television patent was not a PAL patent, but an NTSC-patent. Bruch‘s patent DE 1252731 is called "Color television receiver for a color-reliable NTSC-system". So, Bruch, the "father of the PAL system" did not invented PAL. He only invented a color-reliable NTSC receiver. But the true merits of inventing PAL belongs to an American. In 1951, Loughlin mentioned that a hue control for NTSC is easier to install than the electronics of a "Color Phase Alternation". And without SECAM and the use of the delay line in the SECAM decoder, the PAL system would not developed. So, PAL is a child of NTSC and SECAM.

When PAL color television was introduced in Germany, General Electrics and SONY sold color tv receivers according to Loughlin's patent (so called "Simple PAL receivers" without the delay line), and they had not to pay any licence fees to Bruch or to Telefunken. Loughlin's Simple PAL receivers have stunning color pictures. Together with SONYs trinitron CRT, they had a better color reproduction than Bruch's standard PAL receivers.

Kind regards,
Eckhard

[jeyurkon]

Thanks for the history. I wasn't aware of that.

I spent some time talking to his son, Dr. Reinhard Bruch and he seems like a nice enough fellow. I wonder if he is aware of it.

John

[cbenham]

The "Color Phase Alternation" system tested by RCA-Hazeltine operated at the field rate causing lots of large area flicker. Loughlin got a US patent on it, #2,943,142 granted finally on June 28, 1960, having been filed for on January 22, 1951. More about this is in the George H. Brown book, "And Part of which I Was", Recollections of a Research Engineer, pages 238-239.
Cliff

[yagosaga]

The details of the trouble around the PAL system patent are well-known to insiders in Germany. In 1969, the German newspaper DER SPIEGEL (= The Mirror) published the story of Walter Bruch under the title "Legende gehäkelt" (Crochet the Legend). Other researchers have reported some more details. In 1977, Walter Bruch had to confess in his book "PAL - Das Farbfernsehen", that not he but Bernard Loughlin was the inventor.

Kind regards,
Eckhard

[nasadowsk]

I wonder if the whole motivation behind PAL was ultimately little more than a patent dodge...

[jeyurkon]

Originally Posted by nasadowsk

I wonder if the whole motivation behind PAL was ultimately little more than a patent dodge...

Perhaps, but I hear it's better than "Never Twice the Same Color."

John

[Robert Grant]

I have read elsewhere (cannot remember where now) that Sony PAL was different from either Telefunken PAL or PAL simple.
Specifically, I read that Sony PAL did use a delay line. The delay line stored the color information of every other line (the lines in which R-Y and B-Y were transmitted). During the other lines (in which Y-R and B-Y were transmitted), the delay line output (a copy of the previous line) was fed to the color matrix, with each Y-R line effectively being discarded. The result behaved very much like NTSC-B, thus, Sony PAL sets had the "hue" knob familiar on the other side of the Atlantic.

Is this incorrect?

While we are on the subject of European analog TV history, what is really the difference between system B and System G?

System G supposedly uses an 8 MHz channel, versus 7 MHz for System B. This could imply that some video information would continue above the audio carrier to make the horizontal resolution better (with the quirk of a "gray zone" where the audio carrier would block some details).

However, the visual bandwidth for System G is also quoted as 5.2 MHz, so there would be nothing above the audio carrier (before the unrelated and unforseen addition of Zweiton many years later).

Another question relates to the UK system of a 6 MHz audio offset. 5.5 would have been System B/G, and compatible with much of NATO Europe (the whole reason for abandoning 405?), where as 6.5 MHz (as used by OIRT members) would have given the full resolution of the 8 MHz UHF channels. With 6.0, they got neither!

[ppppenguin]

Standards. We love 'em, so let's have lots of them.

System B/G has a rather narrow vestigial sideband (0.75MHz) and cuts a fair bit of the upper sideband of the colour subcarrier. Also uses phase response pre-distortion at the transmitter to allow for typical receiver IF response. This may have been a good idea at the time but SAW filters made it a slight nuisance.

System I (UK) is a lot cleaner. 1.25MHz VSB, near enough full upper chroma sideband.

Coming back to the original subject, PAL is a lot more resistant to all these problems than NTSC. In a properly designed delay line PAL decoder any phase (hue) errors are converted to saturation errors which are not very visible.

Looking back, we often wonder why certain decision swere made when setting standards. You guys in the US did a wonderful job when you changed the field rate to 59.94Hz rather than tweak the sound slightly. Who likes drop-frame timecode In Europe we're hardly any better, with multiple standards including SECAM which was a nightmare in vision mixers. At least we don't waste transmitter power with 7.5IRE setup.

And finally... PAL was a good idea at the time since it was much less critical than NTSC in several ways. In retrospect this advantage went away pretty quickly as circuit technique etc developed and it's far harder to cleanly decode a PAL signal with comb filters.

[dtuomi]

Originally Posted by Robert Grant

Another question relates to the UK system of a 6 MHz audio offset. 5.5 would have been System B/G, and compatible with much of NATO Europe (the whole reason for abandoning 405?), where as 6.5 MHz (as used by OIRT members) would have given the full resolution of the 8 MHz UHF channels. With 6.0, they got neither!

From what I remember PAL was chosen rather late in the game in the UK. They already had the spec sheets all lined up for NTSC and had even gone so far as to distribute them to BBC engineers.

It could be their choices in audio offset reflected the fact that they originally weren't planning for PAL.

I wish I remember where I had read it, because I remember reading about one engineer having a cheat sheet of NTSC specs were he simply crossed off the NTSC stuff and substituted PAL numbers. Might have been here: http://www.tech-ops.co.uk

David

[Duke Nukem]

From what I remember PAL was chosen rather late in the game in the UK. They already had the spec sheets all lined up for NTSC and had even gone so far as to distribute them to BBC engineers.

The beeb made experimental transmissions with colour on 405 lines in the 50's and a number of such receivers still exist. A lesson learned from the US was that expensive receivers would significantly hamper take up by the public, not helped by the fact that in comparison to the US the UK worker had much less in the way of disposable income. So, at that point in time investing in all the colour equipment in the studios could not be justified.

By the time colour was becoming feasible, the rest of Europe were also looking at introducing colour and the more resiliant PAL was a natural choice. No tint controls needed :-) though having said that the one and only colour TV in my collection - a supposedly posh Dynatron (essentially a Pye in a posh cabinet) has a tint control!

TTFN,
Jon

[andy]

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[Kiwick]

Apparently, the PAL concept was stolen from the RAI research labs in Italy but i don't know the exact story.