Radio teleswitch

A radio teleswitch is a device used in the United Kingdom to allow electricity suppliers to switch large numbers of electricity meters between different tariffs, by broadcasting an embedded signal in broadcast radio signals. Radio teleswitches are also used to switch on/off consumer appliances to make use of cheaper baseload tariffs, such as economy 7.

Each of the user companies (the RTS Users, or Service Providers) has its own database on the Central Teleswitch Control Unit (CTCU), which is an HP Integrity computer running OpenVMS on IA-64 for reliability and clustering technology to minimise downtime.

The database defines how each group of teleswitches belonging to the user-company will control the loads and meter registers connected to it. The CTCU uses the database and certain rules to generate and control a continuous string of messages, which is forwarded to the BBC for transmission.

Although each message will be received by all installed teleswitches, the unique user and group-codes carried by the message ensure that only teleswitches carrying the same combination of codes will act on it.

The Radio Teleswitch Service (RTS) has its origins in the energy management projects initiated in the United Kingdom by the Electricity Council in the early 1980s. Three projects investigated the feasibility of using the telephone network, the distribution network and national radio for large scale energy management purposes. The radio teleswitch project was chaired by Walter Waring, deputy chairman of Eastern Electricity, and supported by the BBC.

The idea of phase modulating control and data signals onto the low frequency carrier wave used for broadcasting the BBC Radio 4 programmes was tested. The BBC was satisfied that there was no discernible distortion of its broadcast service and no infringement of its Royal Charter.

The technique won the Queen's Award for Technology, while its application for controlling consumer tariffs and loads was approved by the Home Office. The project was funded by the CEGB and the mainland electricity boards, which were each allocated one of sixteen message channels. One channel was reserved for testing and the final one was allocated to Northern Ireland when it joined the project.

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