DAB Digital Radio
DAB is another way of broadcasting radio stations, much like FM and AM before it. The difference between previous methods and DAB, however, is that the audio is carried digitally.
FM and AM both require that each radio station broadcast on it’s own unique frequency. This is how you are used to tuning in to radio stations, by scanning the band for a specific frequency. DAB, however, allows many stations to share the same frequency on what is known as a “multiplex”. This is why tuning a digital radio is much easier as your radio provides a list of station names to select from.
Currently in the UK there are two national multiplexes and, here in Bristol, also a local multiplex. There is a limit to the capacity on a multiplex and also to sufficiently cover a large enough area can sometimes require many transmitters. Both the scarcity of capacity on multiplexes and the cost associated with transmission has put DAB out-of-reach for smaller operators.
Small Scale DAB
In the last couple of years, however, new techniques have dramatically reduced the cost and complexity of launching DAB transmissions. This uses new technology known as “Software Defined Radio” (or SDR) in combination with a computer to quickly and cost-effectively begin broadcasting.
It is proposed that this may be the solution to allowing smaller community broadcasters to benefit from carriage on DAB.
The UK regulator Ofcom has announced the advertisement of ten Small Scale DAB trial licenses, covering small geographic areas, to allow those awarded to run a 12-month trial broadcast to prove these theories and guage public opinion. As a result of a consultation process, it is expected that OFCOM will formalise the issue of new DAB multiplex licences in the future, and the current trial licence has been extended until June 2020.
Bristol Digital Radio
Bristol Digital Radio (BDR) is group of commercial, community and student radio stations in the Bristol area who are all interested in broadcasting on DAB as part of these trials.
The stations combined programming, technical expertise and resource to form an application which was submitted to Ofcom along with around 50 other groups.
In June 2015 Ofcom awarded a trial license to Celador Radio for a multiplex to cover the City of Bristol, and transmissions started in October 2015 from a site in Ashton Gate.