BBC Regional logos from the early 70s

I never realised the PM5544 had been broadcast in ITV Regions before ETP1 - this is interesting. As the PM5544 was already widely used throughout Europe, I can't understand why the IBA wanted to create their own electronic test card?

There was a culture amongst the Beeb and IBA at that time, that an 'off the shelf' product wasn't quite good enough for their purposes, and would at the very least have to be modified. Not a totally unreasonable attitude, when you consider that when the UK started TV broadcasting, we were more or less alone, so there was no real equipment manufacturing industry. Both organisations had internal depts that would churn out custom made devices such as test signal generators, and electronic caption equipment, or heavily modify commercial products. The BBC in particular would often request fairly major modifications to broadcast equipment. This policy arguably led to one company, Link Electronics getting into serious trouble in 1986, because they became totally bogged down with the supply of customised cameras for the BBC. The company did just manage to survive, but its camera business did not.

Those internal departments are now gone, but many of the staff went off and started small companies making specialised products for the worldwide broadcasting market so the technical skills and ideas lived on, and were exported.

Returning to your original point, in my opinion the PM5544 would have been perfectly suitable for the IBA, it was (is still) better than ETP1 because it's got a circle, very important these days, with the mixed aspect ratio environment we now live in !

Thanks for the interesting info - I had heard about the BBC modifications, but I didn't realise just how modified they wanted their equipment to be. I know the BBC Test Card G was a modified PM5544.

I may be wrong, but I think there were two significant changes made to the PM5544 by the BBC.

BBC colour bars were (are?) slightly different to the EBU's for some reason that techy types may be able to explain. In practical terms, the BBC colour bars always looked a little brighter to my eye than those on ITV/C4 where the EBU ones were used. The second change was to include six frequency gratings rather than five.

I suspect these changes were probably made by the BBC to help align the PM5544 with Test Card F rather than because there was anything actually "wrong" with the orginal. If I remember, from about the mid 70s, BBC network tended to use the PM5544 for about a month every year instead of TCF although it popped up almost every afternoon on BBC2 in Scotland and the north when the network lines were being used to send material to the regions.

The other changes to the PM5544 were all within the "user options". Occasionally BBC Scotland used to switch off the coloured squares at the side of the circle and play around with the centre cross. I also seem to remember that BBC Scotland's PM5544 did not look quite like the network version... very slightly wider which presumably meant that one of them wasn't quite a true circle!! The giveaway came when BBC Scotland jumped to their test card when London were using the PM5544.

When the IBA experimented with the PM5544 were they using a modified version or the original?

Could the extra frequency grating be because PAL-I (as used in the UK) has a higher vision bandwith of 5.5 MHz compared to the 5.0 MHz of PAL-B/G (as used in the main PAL areas of continental Europe)?

(Our analogue FM sound carrier is at 6.0 MHz rather than 5.5 MHz)

Yes, 'BBC Colour Bars' were 95%, EBU 75%

Details:-

http://www.pembers.freeserve.co.uk/Test-Cards/Test-Card-Technical.html#Bars

The Beeb's modified version of PM5544, TCG, did indeed have an extra frequency grating, because UK luminance bandwidth on System I is 500kHz wider than the European B/G standards .

The version I saw in use in Jersey was the original unmodified version with EBU bars.

I inherited BBC Scotland's PM5544 generator and the 'user options' are little toggle switches on the front of the 19" rackmount. Alas the generator was left switched on for many years and eventually as more stuff occupied the rack above it, it overhated and barbequed. It is now a late PM544 generator!