Analogue 525<>625 standards conversion

[ppppenguin]

DICE (Digital Intercontinental Conversion Equipment) was the world's first digital  standards converter. A brilliant achievement by IBA engineers. We have one at the Broadcast Engineering Museum. Or will do once we can transport it across from our chairman's house. It's a double 19" rack, full height and ******* heavy. See IBA Technical Review volume 8. Can be downloaded here: https://u.pcloud.link/publink/show?code=...foldergrid

In the beginning, conversion was optical. Point a camera at a monitor. Then, few years before DICE, the BBC used polygonal quartz delay lines to store a whole field of analogue video. This allowed them to make the first electronic NTSC<>PAL converter. The delay lines were difficult, to put it mildly. Its first major use was for the 1968 Mexico Olympics.

I wonder if the BBC engineers had read this article by Philips, detailing what was essentially a magnetic framestore.
https://worldradiohistory.com/Archive-C ... w-1960.pdf

I wonder if this would have been easier or harder than the quartz delays. Or was rotating machinery ruled out on principle?

Magnetic videodiscs, not unrelated to this Philips experiment, were subsequently widely used for instant replay in televised sport.

[Richard_FM]

I've got the feeling that optical conversion had been used for events like the Eurovision song contest, especially when 819 lines were involved.

[ppppenguin]

Optical conversion was used from the very first cross channel OB in 1950.

405<>625 electronic conversion is relatively easy. The frame rate is 50Hz in both cases so you only need to store a line of video.This was achieved by the BBC int he CO6/501 converter. This was available in 1964 for the start of BBC2.

Frame rate conversion requires at least a whole frame to be stored. Much harder.

I'm not sure if optical conversion was ever attempted in colour.

[LENINGRAD T2]

In 1949, an interesting Graphechon memory tube was constructed in the RCA laboratory. It allowed, among others, to change the broadcasting system on television. It was made of a memory shield and two electron guns. The Russian tube model is LN102.
Adam

[Murphyv310]

Hi.
A very interesting approach, I wonder how good standards conversion would have been with this method, relatively simple I would think.

[ppppenguin]

Similar concept to the Williams Tube used in some early computers as RAM.