Cable Systems
Cable systems have been around since the 1930s shortly after broadcast radio began. To receive radio signals a transmitter is needed. The transmitter sends signals that the aerial on the receiver collects and the receiver turns these signals into sounds.The transmitter needs to be ‘in line of sight’ of the receiver. The signals will not go through a hill or mountain and they will get weaker with growing distance between the transmitter and receiver. The transmitter is normally mounted on a high tower that is in turn positioned on the highest hill available. Modern mobile phones work the same way. Even satellite phones have to ‘see’ the satellite by being within the satellite’s footprint.
With the first cable systems a large community aerial was erected on a high spot in difficult or remote country for receiving radio signals. A cable was run from this aerial to all the local homes. Consumers connected their radios to the cable which substituted for the aerials on their own radios. It was simple and effective. These systems were called various names; radio relay, radio diffusion or community antenna. They were mostly installed by private companies offering a radio rental service. The radios that were rented did not have tuners. Stations were changed by turning a switch mounted on the wall near the radio. These systems were developed modestly up to the late 1940s when they were upgraded to carry the new television service. The radio rental companies then offered TV rental as well. Again the TVs were not fitted with tuners. These systems used co-axial cable. They were only capable of downstream signalling.
In the 1980s the world of cable systems changed. New cable technology permitted both downstream and upstream signalling on both co-axial and fibre-optic cables, sometimes called two-way inter-active communication. Michael Aldrich played an important role in promoting a new era of consumer telecommunications based on these changes which is documented in this section of the Archive. It should be read in conjunction with ‘Cable Systems’ HMSO 1982 which Michael Aldrich co-authored.