80th Anniversary of BBC TV preview

[Murphyv310]

Thanks to Jeffrey for the info.
A couple of my sets run down to 240 lines OK. I think one day I'll do a comparison and put the results on YouTube.

[ppppenguin]

If you've seen both the programme and Nick Higham's report you may be struck by the relatively poor quality of the 60 line images in the latter. I spoke to Hugh Hunt about this last night. He says it's down to different photomultipliers. For the programme he had the use of some very expensive devices destined for the Large Hadron Collider. Now he has only some relatively cheap devices.

I'm not entirely convinced by that explanation. Ordinary modern photomultipliers are pretty good, as are relatively inexpensive photodiodes. So what else could be wrong? It looks like there are sync jitter problems which are nothing to do with the photodetectors. There may also be issues with the data acquisition system that connects the PMT output to the PC.

Really need some NBTVA people who know about these things from firsthand experience to coment. Steve Ostler was consulted quite early on but this thread in the NBTVA forum says that Dr Hunt went his own way. I'm not a NBTVA member so I can only see this discussion and not cotnribute to it.

http://www.taswegian.com/NBTV/forum/viewtopic.php?f=1&t=2159

[Murphyv310]

I'd agree Jeffrey.
Remember those little "Baird" scanners you could buy from Manchester Uni a few years ago, with a decent LED they worked well and I even managed to lock them up with the multistandard aurora. Surely all the brains there could have got a better result with 60.lines?
Perhaps too much modern technology for what they were trying to do.

[ppppenguin]

AFAIK some of the NBTVA folk can achive this sort of 60 line quality routinely.

Trevor, I think the display is easier than the camera for a mechanical system. And for an electronic system too.

[Lucien Nunes]

We watched en famille and agreed afterwards that the production missed a lot of opportunities, given the input available from expert contributors such as Jeffrey and Paul M. I don't doubt that their participation was invaluable but we had hoped to see and hear more from them and people like them directly, in place of the padding that always seems to creep into programming of this style these days. The brevity of coverage given to the M-EMI system was surprising, but the more I think about it, perhaps we are lucky that any core technical content was included at all, in what was mainly a commemorative programme. For the non-technical viewer, it was probably quite enough to grapple with. The 'reconstruction' concept seems to me to be inherently tricky to pull off, because if an event is important enough in history to merit a reconstruction, it's probably too major to cover effectively in an hour or two of programming. Maybe a strict documentary style would have fallen flat with the target audience, in which case it was a chance worth taking. Props to the engineers!

[ppppenguin]

Thank you, Lucien. I've seen comments in the general press and online that there was too much technical content. So you can't really win.

The problem with telling the story of the M-EMI system is that Danielle George was effectively presented with a "going concern" by Paul Marshall. Paul built that camera over 10 years ago and it works as well as is permitted by an elderly and slightly gassy iconoscope tube. The problem is helium ingress, something that one day in the distant future may trouble a lot of vacuum tubes. Another comparison is that Hugh Hunt got his hands dirty building a FS scanner. As a result he got to understand its limitations from direct experience. Danielle George is a very good engineer and presenter but she freely admits to having no specialist knowledge of the field. Paul and I briefed her on the technology, as you'd expect she picked up the gist very quickly.

Paul's body language when Danielle was handling the iconoscope was priceless

[bobhowe]

Just watched the program & enjoyed it very much good to see how they managed it 80 years ago must have been a massive achievement & it was nice to Jeffery on the show as well

[ppppenguin]

The whole programme has been uploaded to Youtube: https://www.youtube.com/watch?v=tNZB-sfr1T4

I suspect this is unofficial and could get taken down.

[Murphyv310]

Paul's body language when Danielle was handling the iconoscope was priceless

Yes at one point I thought the gun was mighty close to the table, I was waiting for her to say.............. catch

[Dick.1]

Watched this last night ................................. absolutely fascinating.

Like most of us I would have preferred a "proper" documentary approach but I suppose this is all that could be hoped for as it needed to be entertaining as well

Must admit to being disappointed with the aluminium wheel that was jury rigged to run in an open frame & people seeming somewhat surprised that the air was moving around & affecting the balance of the wheel when it was running

Good old days ?

Of course they were & certainly exciting times

Dick.