In the United Kingdom, the roll-out of digital radio has been proceeding since engineering test transmissions were started by the BBC in 1990 followed by a public launch in September 1995. The UK currently has one of the world's biggest digital radio networks, with about 500 transmitters, three national DAB ensembles, one regional DAB ensemble, 48 local DAB ensembles and an increasing number of small-scale DAB ensembles broadcasting over 250 commercial and 34 BBC radio stations across the UK. In London there are already more than 100 different digital stations available. In addition to DAB and DAB+, radio stations are also broadcast on digital television platform as well as internet radio in the UK. Digital radio ensemble operators and stations need a broadcasting licence from the UK's media regulator Ofcom to broadcast.
In the long term there will be a switchover from analogue to digital radio when the AM and FM services will cease. The government has set criteria on the coverage and proportion of digital listening before this occurs. In 2018 the criteria of over 50% of digital radio listening was met which will now require the UK Government to review digital radio in view of a potential switchover. In the same year, the BBC stated it would keep some FM radio for the foreseeable future.
Digital radio in the United Kingdom is being promoted by radio stations and the broadcasting industry on the premise that it provides superior quality sound over AM, a wider choice of radio stations, is easier to use, and is resistant to the interference which other broadcast media are susceptible to. On the other hand, critics say that coverage is not yet sufficient and the quality can be less than that of FM.
In the UK, 65.8% of all radio listening hours by the third quarter of 2021 were through digital platforms, with DAB making up the majority of digital radio listening (65.3% of digital radio listening). In the first quarter of 2020, 66.7% of UK people aged 15+ claimed to have access to a DAB radio set at home.
Digital Audio Broadcasting
Experimental transmissions of the DAB Eureka 147 standard from the Crystal Palace transmitting station by the BBC started in 1990 with permanent transmissions covering London in September 1995. With the expansion of its single-frequency network in the spring of 1998, the BBC national ensemble was available to 65% of the UK population by 2001, 85% by 2004 and 96.4% by 2015. DAB+ full-time broadcasts began in 2016.
The Broadcasting Act of 1996 allowed the introduction of national, regional and local commercial ensembles in the United Kingdom.
The first national ensemble licence for DAB from the Radio Authority was advertised in 1998 and one applicant applied for the licence. The licence was awarded to the GWR Group and NTL Broadcast, who since the launch were renamed Arqiva. The two companies formed the Digital One ensemble, which began broadcasting on 15 November 1999. The Digital One ensemble has grown and is currently available to over 90% of the UK population although an Ofcom report into Digital Radio in 2015 puts robust household coverage at 89.8% of the UK.
Growth and benefits of DAB in the UK
In the United Kingdom, the uptake of DAB has increased since the launch of the BBC national DAB ensemble in 1995. Lower prices, new radio stations and marketing have increased the uptake of DAB radio in the UK. Digital radios were first sold as car radios in 1997, priced around £800, with hi-fi tuners costing up to £2,000 being released two years later. In 2001, Digital One invested in Frontier Silicon to produce a new processing chip which would allow cheaper portable radios to be produced. Roberts Radio, Goodmans and in 2002, Pure Digital's award-winning Evoke series of radios broke the £100 price barrier, and DAB take up has increased since.
The BBC and other DAB broadcasters have been encouraging DAB take up by promoting a number of features which are either new or improve upon former technology in their sales literature. The benefit of DAB is that due to the use of multiplexing technology and encoding technology, broadcasters including the BBC and EMAP have been able to launch exclusive digital radio stations alongside their existing analogue radio stations. Broadcasters also state that DAB offers better reception, without the problems of interference that are more noticeable through analogue radio. DAB radios also come with features such as station lists, so listeners do not need to retune their receivers, as well as scrolling text, providing information such as breaking news, travel information or the latest track information.
DAB has also been marketed as having two major advantages over analogue radio broadcasting in that using MPEG-1 Audio Layer II lossy audio compression technology and more recently DAB+ using High-Efficiency Advanced Audio Coding, parts of the audio spectrum that cannot be heard by humans are discarded, meaning less data needs to be sent over the air. This, as well as multiplexing technology, allows a number of channels to be broadcast together on one frequency as opposed to one channel for analogue radio broadcasts.
National, local and regional DAB ensembles use the same frequency for the area they cover. Using a single-frequency network, an ensemble broadcasting a number of stations can cover the same area as a number of VHF frequencies which would be required to cover the same area for one station. The BBC carried out successful tests of a single-frequency network in London before launching its national DAB ensemble.
Criticism of DAB Multiplex Operators DAB audibly, in some cases, provides worse audio quality than FM – perhaps due to greed of Multiplex Operators wishing to create more services within the same bandwidth by using very low bitrates. In 2020, most commercial stations use only 32–64 kbps (DAB+ with HE-AAC codec) while those stations maintaining the old DAB standard (MP2) have switched to mono with 64–80 kbps. A bit rate of 256 kbps (MP2) has been judged to provide a high quality stereo broadcast signal. The bit rates used by the radio stations on cable and satellite are usually higher. Many internet radio streams also use low bitrates but with MP3 rather than MP2 – providing better audio quality at the same reduced bandwidth (bit rate). On the other hand, an Ofcom survey, which was undertaken due to many consultation responses citing poor DAB quality, found that 94% of DAB listeners thought DAB was at least as good as FM.
In 2006, Ofcom estimated that even after extra spectrum has been allocated to DAB, around 90 local radio stations will be unable to transmit on DAB, either because there is no space for them on a local DAB multiplex, or because they cannot afford the high transmission costs of DAB that the multiplex operators are charging. Ofcom announced in 2005 that it regarded Digital Radio Mondiale (DRM) as an option for local stations unable to secure carriage or unable to pay the high transmission costs of DAB.
On 24 January 2009, Ofcom allowed electrical retailers to be granted a licence to rebroadcast DAB signals within their stores to demonstrate DAB radio sets. The United Kingdom consumer charity, Which? warned that consumers who could not get an adequate DAB signal could be misled by the in-store sets. The Digital Radio Development Bureau replied to the Which? report stating that stores contain a steel structure which produce a Faraday cage effect where DAB signals are blocked out. The DRDB recommended that consumers should check DAB coverage online with their postcode before purchasing a DAB radio to avoid disappointment.
On 24 November 2010, a number of commercial radio operators refused to run an advertisement promoting DAB, one operator stating that it would be "fundamentally immoral and dishonest" until DAB coverage matches that of FM. Commercial radio executives have argued that the BBC should pick up the majority of the cost of expanding the DAB network across the United Kingdom.
DAB+
DAB+ is a major upgrade to DAB. It is not backwards compatible. The main difference is the use of the more efficient HE-AAC which doubles the number of stations up to about 20 in one bouquet. Most European countries quickly adopted DAB+ between 2015 and 2019. Only a small number of DAB-only receivers had been sold before which became worthless. In the UK, with the early success of DAB, the situation is different. In 2020, about half of the stations use DAB+, mostly new services, while the BBC and the big commercial stations continue to use the old DAB standard. DAB+ was first tested in the United Kingdom in 2013 before regular services were launched in 2016. The United Kingdom Government had previously ruled out any transition from DAB to DAB+ for the foreseeable future, a decision backed by the radio industry and the Department for Culture, Media and Sport. The chief executive of the DRDB, Tony Moretta, mirrored the calls by the radio industry and experts not to adopt DAB+ in the UK. In an interview with the TechRadar website in 2009, he claimed that DAB+ was a "red herring" and may not be introduced in the UK for the foreseeable future due to the growing number of digital radio sets currently being sold and used in the future which cannot decode and therefore access DAB+ stations. Independent radio analyst Grant Goddard also stated that there was an economic decision not to adopt DAB+ for both the industry and consumers.
Despite opposition aired to the government regarding the introduction of DAB+ in the United Kingdom by the industry and experts, Ofcom began testing DAB+ on the Brighton Experimental ensemble in January 2013 for a period of one month. In March 2014, the BBC announced that it would undertake a trial of DAB+ in the UK later in the year and on 1 September 2014, Folder Media began a four-month trial of DAB+ on the North East Wales and West Cheshire ensemble.
In early 2016, two new stations launched DAB+ services on the Portsmouth trial multiplex. Sound Digital, operators of one of the national multiplexes, launched three full-time broadcasting DAB+ services on 29 February 2016. Since then a number of stations have launched on DAB+ or switched from DAB to DAB+. As of September 2016, there were over 30 DAB+ stations being broadcast in the UK. In March 2017 the Brighton multiplex became the UK's first to only broadcast DAB+.
The Department for Culture, Media and Sport published minimum specifications for digital radio receivers in the UK in February 2013 which states that a receiver sold in the UK must be capable of decoding a DAB+ stream of up to 144 capacity units. Radios must support DAB+ to receive the digital tick mark. However this is not mandatory and many retailers continue to sell DAB receivers that do not support DAB+.
DAB frequency plan DAB radio stations in the United Kingdom are broadcast on a number of frequency blocks on VHF Band III. The original plan devised in Wiesbaden for the framework of DAB in Europe was to allocate frequency blocks 11B to 12D for UK DAB broadcasting. However, as part of its Review of Radio, Ofcom has expanded the frequency allocations for DAB and has advertised local and a national ensemble licence on blocks outside the original Wiesbaden plan on 10B to 10D and 11A. Block 5A has also been reserved for the launch of local ensembles. In 2015, additional blocks were opened up for small scale DAB trials for an initial period of nine months. Ofcom reiterated the use of a number of frequency blocks between 7D and 9C for any future roll-out of small scale DAB multiplexes in its final report regarding the small scale DAB multiplexes published in September 2016. The first permanent Small Scale DAB licensed were advertised during 2021 with the trial licenses being awarded to the trial licensees.
VHF Band III
United Kingdom VHF Band III