The first high definition TV service

The first high definition TV service

3 November 2020

On 2 November 1936, the BBC began the world’s first ‘high definition’ television broadcast service. Back then, high definition was classed as a minimum of 240 horizontal lines rather than the 1080 horizontal lines of today’s digital high definition television. It was however, very much high definition when compared to earlier systems, like the one pictured above, which were only 30 lines.

Two different systems were tested across six months of transmitting, John Logie Baird’s mechanical system which produced pictures of 240 lines and EMI-Marconi’s electronic system that produced 405 lines. Although Logie Baird’s system was first to be shown in the trial, unsurprisingly, EMI-Marconi’s superior system was chosen as the winner.

In the 1950s, the system was superseded by what we now know as standard definition with a horizontal resolution of 625 lines. Not all of these lines were active picture lines seen by the viewer. Some were reserved for things such as the broadcast of the Ceefax and Oracle teletext information services and later, switching information for widescreen televisions so they displayed images in the correct aspect ratio.

Rank Cintel machine in the 'Media Lab' at The Box

All this has a nice link to two of the objects in our Media Lab. John Logie Baird founded a company called Cintel in 1927. It was bought by the Rank organisation in 1958 and renamed Rank Cintel. Rank Cintel went on to make a range of telecine machines, used thoughout the broadcast industry, for converting film into video for broadcast. A Rank Cintel MKIII telecine (pictured above) is one of the objects on display in the gallery. It's also probably the heaviest, weighing in at 500Kg. It was built in 1985 and still works well and saw regular use by us until a few years ago.

We also have a PYE television from the 1950s on loan from Torquay Museum. It’s not clear if this operated on the 405 lines system or 625, but it’s of the era of the changeover and very much like the television my mum remembers watching the Queen’s Coronation on in 1953!

So, whether you’re watching your favourite soap opera in HD or a natural history documentary in 4K this evening, spare a thought for those early viewers who huddled around a tiny television set to watch something with only 240 lines of resolution!

With thanks to James Gibbs, Media Technician
Top image: John Logie Baird 30 line demonstration, 1926 © Getty