Abstract :
The proposal for the service, which subsequently became known as “Carfax”, was put forward by BBC Research Department in 1971. It was based upon, an extensive review of the requirements, and the resources. Designed to use a single MF resources channel, operating in TDM, it envisaged a closely-spaced network of transmitters which would provide national cover. The operating technique was similar to that used for the maritime beacon service, whereby each station was allocated a brief period in a sequence to transmit its local announcement. Such a method is suited to the spasmodic nature of traffic information, whereby stations could be operated in a selected sequence either automatically or on demand, and simultaneous transmission by those within mutual interfering range would be prohibited. In the light of subsequent developments, the Carfax project can be seen as a unique opportunity which was missed. Even today, none of the methods in use achieves the spectrum efficient service that could have been realised, had it proceeded
