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In 1984 ITT launched the first "digital" TV set. Although there were no digital TV transmissions, the company had spent £20 m over 10 years developing a receiver that processed ordinary analogue TV signals in digital code.
ITT's aim was to simplify manufacture because seven chips did the job of 300 bulky analogue components. But ITT expected the public to pay a 50% premium on the set price for the priviledge of making life easier for ITT.
After two years of predictably slow sales, ITT used the digital circuitry to offer PIP, picture-in-picture. The bulk of the screen showed one channel while a one sixteenth size window in the corner showed another. So the viewer could watch one programme while keeping half an eye on another. Today we take this for granted, but it was a big in 1986.
The system used only 12 kilobytes of memory and the inset picture was so coarse that ITT's publicity photograph wisely showed a simulation. The Multicontrol PIP TV flopped and ITT sold its TV factory in Germany.
American manufacturer DuMont had already tried and failed to sell PIP sets, in 1954. There was no digital circuitry available so DuMont just built two TV sets into one cabinet.
The two cathode ray tube screens were set at angles and a one-way mirror superimposed their images for front viewing. Cross-polarising filters were placed in front of the screens and viewers wore Polaroid spectacles that matched the polarity of whichever image they wanted to watch. Viewers also had to wear headsets that piped the selected soundtrack to their ears only.
In theory, the whole family sat in the same room while some people watched one programme and others watched another. In practice, polarisation dimmed the pictures, there was optical leakage and the system cost more to make than two separate tv sets.