ABSTRACT
Beginnings The concept of television as a practical technology began with the work of a Scot, John Logie Baird, in the early 1920s. His work built on an idea of Paul Nipkov, a German engineer who in 1883 had taken out a patent on a scanning disc that contained a spiral of holes positioned so that when it was spun the holes would scan an entire image, line by line, in one revolution. The brightness of the image at each point would be transmitted by wire and reconstructed by a similar disc synchronized to the disc in the transmitter. Nipkov did not exploit his patent, and it was left to Baird to produce a practical system, using a radio link. In Baird’s transmitter the luminances tracked by the rotating Nipkov disc were recorded and coded as modulations of a radio signal (Figure 13.1).
