Baird Phonovision disc, c 1928.
© National Media Museum / Science & Society Picture Library
Detail of radial pattern on disc. This is one of only six Phonovision discs known to exist, representing the first time television pictures were recorded. Phonovision discs contain the original experimental television recordings of John Logie Baird (1888-1946), recorded from 1927-28, les than two years after his first demonstration of television. With only 30 lines per picture (per television frame), the highest frequency present was low enough to be audible - the video signal could therefore be recorded as an audio signal onto disc.