Rediffusion Wired Vision System

The distribution of Radio (Audio) signals had began in the late 1920's with Broadcast Relay Service , a division of British Electric Traction using their existing overhead power systems which supplied the electricity to Trams and Trolley Busses in many UK towns and cities.
The system of relaying the BBC radio programme into homes quickly caught on as Radio Sets were expensive and reception in city areas quite poor at that time requiring the need for large wire aerials to receive the stations. Audio signals were sent down wires straight to a Loudspeaker Loudspeaker in the home where all that was needed was a Volume control housed in the Loudspeaker.
By 1945 the British Post Office had licensed over 200 providers of Radio Relay Services. Read More See List

When WWll broke out, high definition television broadcasting by the BBC, which had commenced in 1936 from Alexander Palace in London was suspended. To co-incide with the resumption of TV broadcasts by the BBC after the war in 1946, Rediffusion carried out some experiments with vision signals along coaxial cables using the "off air" 45mhz carrier frequency. Because of signal attenuation and severe "Ghosting" the trial was abandned.
Further development continued and the HF. system was adopted using a 9.72MHz carrier with upper sideband video modulation , this system was given the name TDUK1. Read More See Rediffusion Research
With the arrival of a second television channel ( ITV ) in 1955, a new distribution service was designed known as TDUK2. This was a Tete-Beche signal. One program was transmitted at 4.95MHz upper sideband and the second was transmitted at 8.45MHz lower sideband.
By 1963 further development of the wired system took place to accommodate the proposal for 625 line UHF television transmissions which started in 1965 with the BBC2 channel. The TD.80 system (Read More), for distributing a 625-line channel alongside TDUK.2 and TDUK.3 was introduced.
Rediffusion demonstrated a TV signal sent over 1 mile by means of a fibre optic cable running in parallel with the main vision trunk route at Hastings in 1973. The demonstration was a success and comparison could be made between a signal sent over copper or fibre optics. This was thought to be a first for Rediffusion.

With the approach of the 1980's It was realised that many other programmes would shortly be available
and a new transmission system was designed. This was known as System 8, it used 5 coaxial cables each carrying 6 TV channels at VHF. Trials were very successful but by the mid 80's the system was abandoned after the Rediffusion businesses were sold into new ownership.

The Rediffusion Wired Vision Network was a very sophisticated and complex system in its time. The planning, development and engineering required an enormous amount of technical expertise both nationally and internationally.
Though it is not possible to deal with all of the aspects of Wired Vision within these web pages, much information on the subject is covered on the following pages: