Background on digital radio
The principle of digital radio is that the audio signal is converted to a digital format and compressed at the point of broadcasting into a single radio frequency and then decoded by the (listener’s) digital radio set receiver. The main benefit of digital radio is the more efficient use of radio spectrum compared to analogue allowing for more radio services to be delivered to listeners, as well as the delivery of text and visual information.
	In the UK DAB is transmitted via 3 national multiplexes and 55 local (mainly county sized) multiplexes. A radio multiplex consists of a number of DAB radio stations bundled together to be transmitted digitally on a single frequency in a given geographic area.
	The Office of Communications, "Ofcom", is responsible for the regulation and licensing of radio multiplex services (national and local).