The BBC led the field in building out its DAB transmission network. Its DAB services began in London in September 1995, operating from 5 transmitters in a single frequency network. The next phase increased the number of DAB transmitters to 27 which provides coverage for 60% of the UK population. This phase brought BBC DAB transmissions to major metropolitan areas like Belfast, Bristol, Birmingham, Edinburgh, Glasgow, London, Liverpool, Manchester, Newcastle and the main motorway routes of England.

After 2 short term tests in London and Birmingham, long-term commercial radio pilots were operated in London by National Transcommunications Ltd (NTL) and British Telecom (BT). Both commercial trials involved simulcasting as well as experiments with new services.

The three multiplex blocks that operated in London, under extended RSL licences, broadcast the following pilot services :

• BBC Multiplex : Radio 1, Radio 2, Radio 3, Radio 4 and 5 Live (in mono), plus new services. Some of these new services were not broadcast continuously but included Country, Comedy, Opera, Top 40, Jazz, Now (Rolling 10 minute news & info), Weather, Parliament, Five Live Sports Plus, Extra, World Service, Radio Text and Digital Text.

• NTL Multiplex : European Klassik Rock, Heart 106.2, Kiss FM, Liberty Radio (in mono), Melody FM, Sunrise Radio, Talk Radio UK and Virgin Radio.

• BT Multiplex : Classic FM, News Direct, LBC, World Radio Network, GWR Classic Gold, and BBC GLR.

The next major phase of DAB's expansion began when the licensing of commercial radio sector's multiplexes was advertised. This process commenced when the Radio Authority advertised the FIRST and ONLY national multiplex on March 24th 1998.

When making the award of this National DAB Commercial Radio multiplex, the Radio Authority judged applications in accordance with the 1996 Broadcasting Act including the following criteria :-

• How much of Great Britain applicants plan to serve, and by what timetable this will be achieved;

• Whether applicants appear sufficiently resourced to deliver their proposals;

• To what extent the new radio services proposed by the applicants appeal to a variety of tastes and interests;

• How applicants will encourage listeners to invest in new radio sets;

• How fair applicants have been in contracting with those radio stations, or data services, who wish to appear on the multiplex.

The advertisement of LOCAL digital radio multiplex licences got underway as soon as the mix of programme formats on the national multiplex had been determined during Autumn 1998. The Authority is advertising these local licences in batches of three at a time in what has been described as a "fast burn" approach.

The Authority intends to concentrate, in the early years of digital radio development, on the main population centres within the UK. The aim, during this period, will be to facilitate the establishment of up to two local / regional multiplexes (in addition to BBC and commercial national multiplexes) in each of these main conurbations but, apart from in Greater London (where a third multiplex should be available), not to go beyond the density of provision for the foreseeable future.

The general approach in most of these areas will be to replicate the pattern of development of analogue ILR, by first advertising LOCAL multiplexes for areas which broadly correspond to the coverage areas of existing 'first generation' ILR stations, and following this shortly thereafter with REGIONAL multiplexes combining coverage of typically, two or three adjacent multiplex areas. The second phase of regional multiplexes is likely to prove more appropriate for accommodating more specialist formats whose appeal is less dependent upon specifically local programming characteristics. It should also be noted that BBC local radio stations will be assigned capacity on whichever 'tier' of multiplex most accurately matches existing editorial coverage.

The Radio Authority has already made a provisional list of areas which will be eligible for local DAB multiplexes. These can be seen in table below. Five frequency blocks are generally available for local digital services across the UK. However, it should be noted that there are no multiplexes planned for local digital services in Northern Ireland at present. The capacity of each multiplex should allow between six and eight programme services to be carried together with data. On this basis, it can, therefore, be assumed that there is likely to be between twelve and sixteen local programme services IN ADDITION to the national services in DAB core areas.

The Authority proposes that the extended 'working list' of local digital radio licence areas should be advertised in the following sequence : -