There was an interesting BBC programme last week which celebrated the 80th anniversary of the launch night of BBC television. It aimed to re-create the original event as closely as possible, even to the extent of building replicas of some of the technology in use at the time.
For those who don’t know the story, the BBC launched television in 1936 running two types of technology in parallel: the Logie Baird mechanical system and EMI’s vacuum tube-based electronic system. Baird’s system was used first, and then the whole thing was repeated using the electronic system. The original television receivers, of which only 300 had been sold by the launch, had a switch to allow the receiver to be put into Baird or EMI mode – I hadn’t realised that, even on launch day, some receivers were using electronic picture tubes even if the Baird camera system wasn’t.
The Baird mechanical system was incredible: for truly live images it had to use a “flying spot” camera where the scene (the face of a presenter sitting in a pitch black booth) was raster-scanned with a high intensity dot of light and the resulting reflected light level picked up by a photo-sensor. In order to achieve 240 lines of resolution, two rotating discs were used; one a metre in diameter and spinning so fast its edges were almost supersonic, and a synchronised slower disc with a spiral mask which selected one of several sets of dots on the main disc.
More general scenes of groups of performers and so on were recorded live to film which was developed in a portable ‘lab’ mounted beneath the camera, ready to be scanned by a flying spot scanner some 54 seconds later – this was effectively the first ever telecine machine. The transition from live to telecine sections required logistical coordination around the 54 second delay, meaning that the performers had to start 54 seconds before the live announcer stopped talking, and the announcer had to wait in silence after the performance ended before someone jabbed him in the ribs through a hole in the side of the booth and he could start talking again. (I found this whole thing baffling: why was it important that any of it was truly ‘live’? Why not just do it all delayed by 54 seconds? Perhaps, as was implied in the program, the telecine images were not quite as crisp as the live..?).
Anyway, the writing was on the wall for the mechanical system, and the six month competition was terminated after only three months. My question is: why did it take so long? Why did people go to such heroic lengths to pursue a solution that was so obviously doomed? Perhaps men’s fascination with spinning discs in preference to electronic solutions is universal. I have no doubt that there were some diehards who thought that the mechanical system somehow captured a better picture than a soulless glass tube.
The Engineering Department of Cambridge University had the fun of developing the replica flying spot camera (although with only 60 lines of resolution as opposed to the original 240). Things got a bit fraught in the build up to the ‘launch’ however: a persistent mechanical howl from the disc mechanism threatened to ruin everything. It seemed to take several hours of effort and anguish before someone had the bright idea of applying a drop of oil…
None of the original presenters, performers or staff present at the launch night are still with us, but the BBC did manage to track down a 104 year old engineer who worked for Baird. The launch of television seems like so long ago, and yet this man was already 24 when it happened. He is still sharp as a pin and when Hugh Hunt of Cambridge University told him he was building a replica flying spot machine using an aluminium disc instead of the original steel, his brow furrowed immediately and he asked “Are you sure aluminium will be strong enough to withstand the centrifugal force?”.
I enjoyed seeing the old abandoned studios in Alexandra Palace, and Paul Marshall‘s barn full of old TV equipment, including some of the earliest camera tubes in existence. He has built a working camera based on a genuine Iconoscope tube, using modern electronics to drive it, giving us a close re-creation of pre-war electronic TV pictures. I somehow find old TV equipment quite moving; TV was an important part of my childhood and I can’t help but think of the snippets of the golden past that might have been captured through those lenses.