The fundamental principle behind a television picture is really quite straightforward: in the recording of television pictures, the brightness levels and saturation are converted into electronic signals. These are then transferred via aerial, cable or satellite to the television set where they are converted back into the corresponding brightness level and rendered visible on the screen.

The human eye registers a continuous sequence of movements when there is a frequency of 16 pictures per second or more. However, at such a low refresh rate we would soon tire, since our eyes cannot store the pictures they register for long. In order to ensure “fluid motion,” a refresh rate of at least 50 hertz is required. The transmission of 50 or more pictures per second would however exceed the available transmission bandwidth, which is why transmission was developed in half pictures.

A full picture is separated into two half pictures by means of a process known as interlacing. The half pictures are transmitted displaying odd and then even lines, with the 1st, 3rd, 5th and then the 2nd, 4th, 6th and so on, with a frequency of 25 hertz, to achieve a total frequency of 50 hertz for the full picture.

At the end of the 19th century, people were already working on the problem of how a moving image could be scanned and transmitted as an electronic impulse. The concept was tested successfully with sound, but it remained impossible to transmit images. The Berlin student Paul Gottlieb Nipkow found an initial solution in 1884. Using a rotating disk with holes arranged in a spiral, he managed to scan a picture point by point so quickly that it could be transmitted electronically. However, reception remained a problem. At that time there was no current pulse powerful enough to illuminate a screen.

Even before the end of the 19th century attempts were being made to find alternatives: physicists experimented with electron beams emitted from cathodes into evacuated glass tubes which were concentrated through apertures to produce fluorescent spots. Electrical and magnetic force could be used to direct these electron bundles onto any part of a fluorescent layer, which amplified the brightness of the beam.

In 1897, Karl Ferdinand Braun invented the “Braun tube” which is still the core component of most televisions today. The cathode ray tube provided better picture quality than the mechanical disks. The first truly successful television camera devices were the iconoscope, an electron beam dissector invented by the Russian-born American physicist Vladimir Kosma Zworykin in 1923, and the image dissector developed a short time later by the American electrical engineer Philo Taylor Farnsworth.

In 1928, a television picture was presented to a marvelling public at the Berlin Radio Exhibition. However, they had to take a very close look, as the picture was just four centimetres square.The first major event involving the new medium was the 1936 Olympic Games, which were televised using the first mobile outdoor camera for live broadcasts. Following World War II, television finally found its way into the living room.

Colour TV was introduced in the United States in the 1950s and it was rolled out in the UK and across Europe in 1967. Today’s television is characterised by brilliant picture quality and a vast range of channels. The near future will bring digital and interactive television with games, text-messaging, home banking and e-commerce. But the good old television set is here to stay.