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Standards

Page history last edited by David Samways 5 years, 5 months ago

 

 

 

 

 

At this time the UK, and Europe for that matter, did not have a colour transmission system selected but the USA did. There were colour test transmissions after normal closedown though and we used to watch these on an old converted American receiver. It had been decided that it was time that a decision was made and we were tasked to produce example systems to be demonstrated to the high and mighty of the EBU/CCIR and others so that the best system could be chosen. This initially involved just two cameras, the two just mentioned; these were demonstrated at the BBC Lime Grove studios. However, we showed three systems (1) A modified NTSC (National Television System Committee (USA)) system, (2) PAL (Phase Alternate Line) a modified version of the NTSC system developed in Germany and (3) SECAM (SEquential Couleur Avec Memoire) a French system. As I expect you know the PAL system was chosen for the UK but elsewhere it became a bit political. Counties in the Europe, the Middle- East and Africa that were not, or did not want to be, aligned to America went for SECAM. As a result engineers renamed it as “Something Essentially Contrary to the American Method”. Unfortunately SECAM was, at that time, a pig to use in the studio as it was difficult to mix two or more signals without a lot of complication. On the other hand two PAL signals can be mixed with just two resistors (provided the signals are synchronous). For this reason many studios, certainly those that we installed, were PAL internally and the signal was changed for transmission only. Following on from the Lime Grove demonstrations we staged a further one at the English Electric base in the Strand. This showed four cameras variants with some cunning processing that I had strung together (still valves). The photo of the cameras with the model was taken at that time. Sadly Pru, the model in the picture, died in an air crash a short while later. The demonstration was aimed at gaining a consensus on the camera configuration. I am not sure if that aim was actually achieved. We had the inevitable Press Day with drinks and lunch arranged in a suite upstairs. The suite had a balcony area with large glass sliding doors. One press guy who obviously had a good thirst, and had quenched it, walked straight into the glass with a plate piled high with salad. His face looked slightly bemused has his lunch slithered down the glass.

 

The decision to proceed with PAL was actually made in 1966 and transmissions formally started in 1969, 39 years ago last week as I write this account (2008!). With the die cast it was time to get our fingers out if we were to have cameras to sell for the new service.  

 

With the USA and UK using different TV systems there was a problem in exchanging programmes on video tape. Some form of Standards Converter is needed. One way was to display the incoming tape on a small monitor and film it (Dad’s Army fans may have seen one of these used just before Christmas – I was surprised that the colour information was good enough to recover). This got over the fact that the American signal had only 525 lines, but the frame rate problem mentioned above still was there. Another system used diner plate sized polygons of glass with transducers bouncing a pressure wave around it. This allowed the picture to be stored and retimed as required, if you had a large set of diner plates. The signal from these systems was rather noisy and there were unwanted reflections within the block that made the image a bit messy. I believe ITN had one but I’m not sure who else might have used that system.

 

In 1969 our Engineering Manager (he that was grinning at Judith) came up with an idea using a camera tube as a storage device. My team (four engineers at that time) was tasked to work on it. We had gone a little way ahead when I realised a bit of a snag that would give rise to a nasty low frequency flicker effect. Oh dear! So we needed another new job. At the time we thought some kind of digital solution would be best but the current technology could not support the speed or the volume of storage that we needed. Six years later it did, but that is another story in someone else’s lab.

 

 

 

Standards Conversion equipment

 

Model number 

 

Description  Comments  Dates (approx.)  Details 
BD898  Standards Conversion Equipment    1960 here
B3562  Electronic Standards Converter    1965 here
B3564  Digital Standards Converter    c. 1980 here
B3374  SECAM Coder    c. 1980 here

 

 

Television RF Monitoring Service

 

Marconi can provide customers with a comprehensive service to ensure all transmissions are in accordance with published world standards.  Click here for details.

 

 

Digital Intercontinental Conversion Equipment (DICE)

 

 

Articles

 

DICE at ITN by P.J. Marchant 1976 click here

 

 

Press cuttings

 

 

 

 

 

 

 

 

 

 

 

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