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Digital terrestrial television in the United Kingdom encompasses over 100 television, radio and interactive services broadcast via the
United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Europe, off the north-western coast of the continental mainland. It comprises England, Scotland, Wales and North ...
's terrestrial television network and receivable with a standard television set. The majority of
digital terrestrial television Digital terrestrial television (DTTV or DTT, or DTTB with "broadcasting") is a technology for terrestrial television in which land-based (terrestrial) television stations broadcast television content by radio waves to televisions in consumers' ...
(DTT) services, including the five former analogue channels, are broadcast
free-to-air Free-to-air (FTA) services are television (TV) and radio services broadcast in unencrypted form, allowing any person with the FTA Receiver, appropriate receiving equipment to receive the signal and view or listen to the content without requiring ...
, and a further selection of encrypted
pay TV Pay television, also known as subscription television, premium television or, when referring to an individual service, a premium channel, refers to subscription-based television services, usually provided by multichannel television providers, b ...
services (such as
Racing TV Racing TV (formerly Racing UK) is a British television channel with 34 racecourses as shareholders and fixtures from 61 racecourses broadcast live on its output. As Racing UK grew several other business units and joint ventures were developed un ...
) are also available.
Freeview Freeview may refer to: * Freeview (Australia), the marketing name for the digital terrestrial television platform in Australia * Freeview (New Zealand), a digital satellite and digital terrestrial television platform in New Zealand *Freeview (UK), ...
is the only DTT service since
Top Up TV Top Up TV was a pay TV service in the United Kingdom which launched in March 2004, operating on the digital terrestrial television platform. The aim of the service was to "top up" Freeview customers by providing additional content and service ...
closed in 2013.
BT TV BT TV is a subscription IPTV service offered by BT; a division of United Kingdom telecommunications company BT Group, and was originally launched as BT Vision in December 2006. As of the end of June 2019, BT TV had 1.9 million customers. ...
services are carried via
IPTV Internet Protocol television (IPTV) is the delivery of television content over Internet Protocol (IP) networks. This is in contrast to delivery through traditional terrestrial, satellite, and cable television formats. Unlike downloaded media, ...
signals. The digital broadcasting technology adopted in the UK is the
DVB-T DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in Febr ...
system (Digital Video Broadcasting – Terrestrial) carrying compressed digital audio, video and other data in a combined transport stream, using modulation. A total of eight national and one local 'multiplexes' are broadcast in the UK, guaranteed to reach over 90% of the country. Three of the multiplexes, carrying the free public service channels operated by the
BBC #REDIRECT BBC #REDIRECT BBC Here i going to introduce about the best teacher of my life b BALAJI sir. He is the precious gift that I got befor 2yrs . How has helped and thought all the concept and made my success in the 10th board exam. ...
...
,
ITV ITV or iTV may refer to: ITV *Independent Television (ITV), a British television network, consisting of: ** ITV (TV network), a free-to-air national commercial television network covering the United Kingdom, the Isle of Man, and the Channel Islan ...
,
Channel 4 Channel 4 is a British free-to-air public broadcast television network operated by the state-owned enterprise, state-owned Channel Four Television Corporation. It began its transmission on 2 November 1982 and was established to provide a four ...
, S4C and Channel 5, are guaranteed wider coverage still, reaching 98.5% of the country including areas dependent on low-power local relays. In the UK, the switchover from analogue to digital TV started on 17 October 2007 and was completed on 24 October 2012. Each group of regional transmitters had its analogue broadcasts switched off at a certain point between those dates.


Receiving and recording

Digital Terrestrial Television is commonly received by means of a compatible
set-top box A set-top box (STB), also colloquially known as a cable box and historically television decoder, is an information appliance device that generally contains a TV-tuner input and displays output to a television set and an external source of sign ...
or integrated digital television (IDTV), connected to an appropriate receiving antenna. In most cases, reception is possible using aerials originally used for analogue television. Transmissions may be recorded in many ways – such as via the connection of a set-top-box to an existing 'analogue'
video Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syste ...
or DVD recorder, or by the use of newer models of such recorders which have built-in digital tuners. However, the most common option is by the use of set-top-boxes which incorporate a hard disk drive, and allow the recording of the digital signal directly to disk, for later replay. Recording on such boxes, known as Personal Video Recorders or PVRs, is more convenient, as programmes may be easily selected for recording from an on-screen programme guide, with no need to specify explicit start and end times for recordings, and no need to program more than one piece of equipment. Many television services which incorporate DTT channels in their service offering – e.g. Top Up TV,
BT TV BT TV is a subscription IPTV service offered by BT; a division of United Kingdom telecommunications company BT Group, and was originally launched as BT Vision in December 2006. As of the end of June 2019, BT TV had 1.9 million customers. ...
, and
TalkTalk Plus TV TalkTalk TV is a UK-based consumer television and video on demand service, operated by the TalkTalk Group that originally launched in 2000. In September 2012, the current TalkTalk TV was launched in partnership with YouView. Its television a ...
, offer set top boxes with such a recording facility. Non-subscription DTT PVRs are also available and are often sold under the 'Freeview+' banner (formerly Freeview Playback.) There also exist a variety of solutions to enable the viewing and recording of DTT programmes on personal computers, with various TV cards or USB tuners available for use with a variety of software packages, including
MythTV MythTV is a free and open-source home entertainment application with a simplified "10-foot user interface" design for the living room TV. It turns a computer with the necessary hardware into a network streaming digital video recorder, a digital ...
and
Windows Media Center Windows Media Center (WMC) is a defunct digital video recorder and media player created by Microsoft. Media Center was first introduced to Windows in 2002 on Windows XP Media Center Edition (MCE). It was included in Home Premium and Ultimate ...
. Most cards or tuners include their own software in the package also.


Features

Digital Terrestrial Television provides many more channels. For some viewers it offers much improved reception compared to analogue broadcasts (although these had been entirely discontinued in the UK by 2012), including 16:9 anamorphic widescreen. A number of interactive services are also offered. An eight-day
Electronic Programme Guide Electronic programming guides (EPGs) and interactive programming guides (IPGs) are menu-based systems that provide users of television, radio and other media applications with continuously updated menus that display scheduling information for ...
(EPG) is available and allows viewers to see programme descriptions and broadcast times well in advance. PVRs will make use of this facility allowing recording timers to be set. This Eight-Day EPG was not an original feature of the Digital Terrestrial system, therefore some early receivers, such as receivers originally made to operate with the
ONdigital ITV Digital was a British digital terrestrial television Broadcasting, broadcaster which launched a pay-TV service on the world's first digital terrestrial television network. Its main shareholders were Carlton Communications plc and Granada ...
service, will only display details of 'now and next' programme information. A fourteen-day Top Up TV EPG was an alternative which was available to TUTV-branded PVRs.


History


Development and launch

Digital terrestrial television launched in the UK on 15 November 1998, just after digital satellite television on 1 October 1998. The technology required that the UK government license the broadcast of channels in six groups, or
multiplex Multiplex may refer to: * Multiplex (automobile), a former American car make * Multiplex (comics), a DC comic book supervillain * Multiplex (company), a global contracting and development company * Multiplex (assay), a biological assay which measu ...
es (abbreviated to 'mux') labelled 1, 2, A, B, C, and D. The
Independent Television Commission The Independent Television Commission (ITC) licensed and regulated commercial television services in the United Kingdom (except S4C in Wales) between 1 January 1991 and 28 December 2003. History The creation of ITC, by the Broadcasting Act ...
(ITC) allocated each existing analogue terrestrial channel half the capacity of a multiplex each. This meant the BBC got a multiplex to themselves (Multiplex 1), ITV and Channel 4 shared Multiplex 2 (though 3% of the capacity was given to
Teletext Ltd. Teletext Ltd was the provider of teletext and digital interactive services for ITV, Channel 4 and Five in the United Kingdom. Origins ''Teletext Ltd'' started providing teletext services for ITV and Channel 4 on 1 January 1993, replacing th ...
) and Channel 5 and S4C shared Multiplex A. The remaining spectrum (Multiplexes B, C and D) was then auctioned off. A consortium made up of
Granada Granada (,, DIN 31635, DIN: ; grc, Ἐλιβύργη, Elibýrgē; la, Illiberis or . ) is the capital city of the province of Granada, in the autonomous communities of Spain, autonomous community of Andalusia, Spain. Granada is located at the fo ...
and
Carlton Carlton may refer to: People * Carlton (name), a list of those with the given name or surname * Carlton (singer), English soul singer Carlton McCarthy * Carlton, a pen name used by Joseph Caldwell (1773–1835), American educator, Presbyterian ...
(members of the ITV network, which have now merged to form
ITV plc ITV plc is a British media company that holds 13 of the 15 regional television licences that make up the ITV network (Channel 3), the oldest and largest commercial terrestrial television network in the United Kingdom. ITV plc is listed on the ...
) and
BSkyB Sky UK Limited is a British broadcaster and telecommunications company that provides television and broadband Internet services, fixed line and mobile telephone services to consumers and businesses in the United Kingdom. It is a subsidiary of ...
successfully bid for these licences, and set-up the subscription ONdigital service, though BSkyB left the consortium prior to launch. The BBC made some use of its multiplex for three of its then four new television services;
BBC Choice BBC Choice was a British digital television channel which was owned by the BBC and was launched on 23 September 1998. It was the first British TV channel to broadcast exclusively in digital format, as well as the BBC's second non-analogue-terres ...
(which had started on 23 September 1998 with four national variations),
BBC News 24 BBC News (also known as the BBC News Channel) is a British free-to-air public broadcast television news channel for BBC News. It was launched as BBC News 24 on 9 November 1997 at 5:30 pm as part of the BBC's foray into digital domestic telev ...
and
BBC Parliament BBC Parliament is a British free-to-air public broadcast television channel from the BBC that broadcasts live and recorded coverage of the House of Commons, House of Lords and Select Committees of the British Parliament, the Scottish Parliament ...
(albeit in sound only). ITV initially used their space to house
ITV2 ITV2 is a British free-to-air television channel owned by ITV Digital Channels, a division of ITV plc. It was launched on 7 December 1998. For a number of years, it had the largest audience share after the five analogue terrestrial stations, a ...
(from 7 December 1998) in England and Wales, You2 (later UTV2) in Northern Ireland and S2 in Scotland (now both ITV2), as well as
GMTV2 GMTV (an acronym for Good Morning Television), now legally known as ITV Breakfast, ITV Breakfast Broadcasting Limited, was the name of the national ITV (TV network), Channel 3 breakfast television contractor/licensee, broadcasting in the Unit ...
during the early mornings. Channel 4 used their space for subscription channels
FilmFour Film4 is a British free-to-air television network owned by Channel Four Television Corporation launched on 1 November 1998, devoted to broadcasting films. While its standard-definition channel is available on Freeview and Freesat platforms, it ...
and E4 which, although not part of ONdigital, would be paid for and were only available through an ONdigital subscription. Channel 4's nationwide coverage on 'mux' 2 enabled it to be received terrestrially throughout much of Wales for the first time in its history, where previously only S4C had been available. Consequently, S4C's digital service, 'S4C Digidol' carries only Welsh-language programming, in contrast to S4C analogue which also carries English-language programmes commissioned and transmitted by Channel 4 in other parts of the UK. Channel 5 sold its half of Multiplex A to the owners of the other half of the multiplex, S4C, who set up a subsidiary called
S4C Digital Networks S4C Digital Networks (SDN) is a company that operates one of the six multiplexes of channels on digital terrestrial television in the United Kingdom. It is now wholly owned by ITV plc. History When digital terrestrial television was first la ...
(SDN) to manage the multiplex and rented most of it out to ONdigital as well as some space to the BBC who launched
BBC Knowledge BBC Knowledge was a British television channel which was owned by the BBC and was launched on 1 June 1999, broadcasting documentary, cultural and educational programmes. It was shut down on 2 March 2002, and was replaced by BBC Four. History L ...
on 1 June 1999, at a time when technical capabilities limited the number of stations it could carry on its own multiplex. S4C chose not to carry S4C Digidol and its newly launched digital Welsh Assembly station,
S4C2 S4C (, ''Sianel Pedwar Cymru'', meaning ''Channel Four Wales'') is a Welsh language free-to-air Public service broadcasting in the United Kingdom, public broadcast television channel. Launched on 1 November 1982, it was the first television ch ...
outside Wales, preferring to sell the space instead. Consequently, some ONdigital services were not available on Welsh transmitters. While the BBC was seemingly concerned with delivering a service of good technical quality, other broadcasters chose to deliver a larger number of channels rather than optimise service reliability and picture quality.


ITV Digital

ONdigital had problems from the start, and renaming the service
ITV Digital ITV Digital was a British digital terrestrial television broadcaster which launched a pay-TV service on the world's first digital terrestrial television network. Its main shareholders were Carlton Communications plc and Granada plc, owners o ...
on 11 July 2001 failed to help the matter. All subscription services except E4 and FilmFour went off-air on 1 May 2002 after the consortium collapsed, explained as being due to paying too much for the television rights for
The Football League The English Football League (EFL) is a league of professional football clubs from England and Wales. Founded in 1888 as the Football League, the league is the oldest such competition in the world. It was the top-level football league in Engla ...
. However, the choice of 64QAM broadcast mode, the fact that at least 40% of homes would need new aerials to receive it, a high
churn rate Churn rate (sometimes called attrition rate), in its broadest sense, is a measure of the number of individuals or items moving out of a collective group over a specific period. It is one of two primary factors that determine the Steady state, stead ...
, an insecure hackable
encryption In cryptography, encryption is the process of encoding information. This process converts the original representation of the information, known as plaintext, into an alternative form known as ciphertext. Ideally, only authorized parties can decip ...
system, the cost of having to provide free set-top boxes, and aggressive competition from BSkyB all contributed to ITV Digital's spiraling costs, before shareholders Granada and Carlton called a halt to the venture.


Freeview

As ITV Digital had collapsed, the rights reverted to the regulator and the ITC invited bids for the space on Multiplexes B, C and D. The Freeview consortium was formed by the BBC, transmitter company
National Grid Wireless Arqiva () is a British telecommunications company which provides infrastructure, broadcast transmission and smart meter facilities in the United Kingdom. The company is headquartered at the former Independent Broadcasting Authority headquarters ...
(known at the time as Crown Castle UK) and
BSkyB Sky UK Limited is a British broadcaster and telecommunications company that provides television and broadband Internet services, fixed line and mobile telephone services to consumers and businesses in the United Kingdom. It is a subsidiary of ...
. This consortium (legal name DTV Services Ltd and trading under the "Freeview" brand) won and launched a new service. Dropping the failed ITV Digital business model, Freeview launched on 30 October 2002 with free television channels only, and made digital radio stations available on television receivers for the first time. The BBC controlled one Multiplex (B) for its own services, and Crown Castle/National Grid the other two (C & D) for commercial services, though the Community Channel also operated on Multiplex B. The BBC's second multiplex has allowed it to televise BBC Parliament where it had previously only been available in sound, allowed BBC Knowledge and its successor, BBC4, to stop renting space from SDN for coverage, and allowed for special video screens in its interactive service BBCi, for use during sporting events such as
Wimbledon Wimbledon most often refers to: * Wimbledon, London, a district of southwest London * Wimbledon Championships, the oldest tennis tournament in the world and one of the four Grand Slam championships Wimbledon may also refer to: Places London * ...
and carrying loops of news headlines and weather, (services already provided on digital satellite) On 11 October 2005, ITV plc and Channel 4 joined the Freeview consortium and in the same year ITV plc also bought SDN and as such they gained control of Multiplex A.


Top Up TV

The space ITV Digital had rented on other multiplexes initially became empty again, but some were rented out to allow new channels to launch. In May 2004 Top Up TV was launched to provide subscription content in hitherto unused space on multiplex A, rented from Channel 5 and additional services transmitted by Channel 4 on their own capacity on Multiplex 2. TCM purchased its own slot throughout England,
Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...
and
Northern Ireland Northern Ireland ( ga, Tuaisceart Éireann ; sco, label= Ulster-Scots, Norlin Airlann) is a part of the United Kingdom, situated in the north-east of the island of Ireland, that is variously described as a country, province or region. Nort ...
from the multiplex owner, SDN, but rents from
Sit-up Ltd Sit-Up Ltd., traded as Bid Shopping, was an English broadcaster which launched in 2000. It operated a portfolio of falling price shopping television channels to over 12 million homes in the UK. History On 1 April 2009, it was announced that S ...
in Wales, timesharing with
bid tv Shop at Bid was a British television shopping channel that ran daily auctions and later fixed price demonstrations. It was the world's first channel of its kind. It launched as ''Bid-Up.tv''. The channel was owned by Bid Shopping. History Bi ...
. Multiplex A is ultimately owned by ITV Plc via its SDN acquisition, but ITV only has involvement with Top Up TV channels via Channel 5. In September of the same year, Top Up TV began operating solely on Multiplex A, as Channel 4 reclaimed the
bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...
on Multiplex 2 for its own services
More 4 More4 is a British free-to-air television channel, owned by Channel Four Television Corporation. The channel launched on 10 October 2005. Its programming mainly focuses on lifestyle and documentaries, as well as foreign dramas. Content When ...
, E4, and most recently
Film4 Film4 is a British free-to-air television network owned by Channel Four Television Corporation launched on 1 November 1998, devoted to broadcasting films. While its standard-definition channel is available on Freeview and Freesat platforms, i ...
. In October 2006, Channel 5 launched two new free-to-air digital channels,
Five Life 5Star (stylized as 5STAR) is a British free-to-air television channel owned by Paramount Networks UK & Australia and a sister channel of Channel 5. It originally launched as the female-orientated Five Life on 15 October 2006, and was relaunc ...
and
Five US 5USA is a British free-to-air television channel. It is owned by Paramount Networks UK & Australia and is a sister channel of Channel 5 (UK), Channel 5, 5Action, 5Star and 5Select. It was launched on 16 October 2006 as Five US and was the secon ...
, using capacity formerly leased out to Top Up TV. This left Top Up TV with a reduced number of video streams. In November 2006, the company launched ''Top Up TV Anytime'', a service which broadcasts overnight ''"downloads"'' which are recorded by a proprietary Top Up TV Anytime
personal video recorder A digital video recorder (DVR) is an electronic device that records video in a digital format to a disk drive, USB flash drive, SD memory card, SSD or other local or networked mass storage device. The term includes set-top boxes with direct to d ...
(PVR). At the same time, they started reducing the linear service. On 19 April 2006, Ofcom ruled that, on request of each
multiplex Multiplex may refer to: * Multiplex (automobile), a former American car make * Multiplex (comics), a DC comic book supervillain * Multiplex (company), a global contracting and development company * Multiplex (assay), a biological assay which measu ...
operator, the '
free-to-air Free-to-air (FTA) services are television (TV) and radio services broadcast in unencrypted form, allowing any person with the FTA Receiver, appropriate receiving equipment to receive the signal and view or listen to the content without requiring ...
channels only' requirement put in place at the launch of Freeview in 2002 may be lifted on Multiplex B, C and D. The effect of this ruling is that if a Mux operator requests the restriction to be lifted, their multiplex may carry pay TV services. Ofcom says that the digital television market has changed significantly since 2002. Consequently, it believes that this restriction is no longer required. During the consultation, 9 of the 12 responses from broadcasters were in favour of removing the restriction. These included the BBC. The BBC agreed that the digital television market had changed substantially since 2002, and that Top Up TV probably couldn't afford the current cost of DTT slots anyway. The BBC suggested that the deregulation should be conditional on a number of further changes to regulation. These included that Ofcom changes the transmission mode of broadcast on all multiplexes from 16
QAM Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signa ...
to 64QAM so more services could be squeezed onto the digital terrestrial platform. However, Ofcom rejected these suggestions, saying they were outside the scope of the consultation. Out of the three that opposed, one was Channel 4, which has been putting in place a portfolio of free-to-air channels, among them Film4 which was made free-to-air across all platforms on 23 July 2006. Channel 4 argued that the number of free channels available has been the major driving force behind the massive success of the platform – there are now more than 10 million Freeview boxes in use. A number of broadcasters requested that their replies were kept confidential. These include ITV and BSkyB. However, it is believed that ITV opposed the plan and BSkyB supported it. In addition to replies from broadcasters, there were 21 replies from individuals. Of these, 20 opposed the change. The channels on Multiplexes B, C and D are those owned by the Freeview consortium and include the three Sky channels on the platform and the
UKTV UKTV Media Limited, simply known as UKTV, is a British multi-channel broadcaster, which, since 2019, has been wholly owned by BBC Studios (formerly BBC Worldwide), a commercial subsidiary of the BBC. It was formed on 1 November 1992 through ...
channels. However, Ofcom believes that in the short to medium term, it is unlikely existing free-to-air channels will convert to pay TV. This is because, firstly, Multiplex B is run by the BBC, which is not expected to request the removal of the free-to-air requirement. Secondly, due to the nature of the contracts the channel broadcasters hold with multiplex operators and content providers, it is unlikely a channel will be able to change to pay TV. It was announced on 8 February 2007 that BSkyB intended to withdraw Sky Three, Sky News and Sky Sports News from the platform in the summer of 2007. BSkyB had said that it intended to replace them with 4 of its subscription channels. It also said that it would use an alternative (
MPEG4 MPEG-4 is a group of international standards for the compression of digital audio and visual data, multimedia systems, and file storage formats. It was originally introduced in late 1998 as a group of audio and video coding formats and related tec ...
) codec, which would enable a greater number of channels to be broadcast, but would require the purchase of new equipment for those who wished to receive the new service. On 6 October 2007 Ofcom said that the plans for a new subscription service raised competition concerns and may have to be scrapped.


2008 update issues

During 2008, a rolling programme of transmitter updates caused approximately 250,000 set-top boxes to stop working. Freeview had warned consumers in advance of the update, which was phased over a three-month period. The problem affected a specific range of older units, and was caused by an increased Network Information Table (channel list) exceeding the memory available in some set-top boxes. This had been part of the specification that was available and implemented in the very early OnDigital boxes, but not in those using the SetPal chip set. Affected consumers were advised to buy new set-top boxes.


Digital switchover


Summary

The UK Government's intention was that
digital terrestrial television Digital terrestrial television (DTTV or DTT, or DTTB with "broadcasting") is a technology for terrestrial television in which land-based (terrestrial) television stations broadcast television content by radio waves to televisions in consumers' ...
would completely replace
analogue terrestrial television in the United Kingdom Analogue terrestrial television in the United Kingdom was originally the method by which the significant majority of viewers in the UK, the Channel Islands and the Isle of Man received television. Analogue terrestrial television broadcasts have f ...
by 24 October 2012. This process was known as "
Digital Switchover The digital television transition, also called the digital switchover (DSO), the analogue switch/sign-off (ASO), the digital migration, or the analogue shutdown, is the process in which older analogue television broadcasting technology is conv ...
", or DSO. The industry association for digital television in the UK,
Digital TV Group The DTG (Digital TV Group) is the association for British digital television broadcasters and annually publish and maintain the technical specifications for digital terrestrial television (DTT) in the United Kingdom, which is known as the D-Boo ...
, was responsible for co-ordination between Freeview and other digital services. DTG licensed suitable equipment to bear the Digital Tick and Freeview Playback Logos to identify PVRs and other devices designed to work through switchover, and to raise awareness of DTT product quality and standards. Digital terrestrial television is broadcast using the
DVB-T DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in Febr ...
international standard for
standard-definition Standard-definition television (SDTV, SD, often shortened to standard definition) is a television system which uses a resolution that is not considered to be either high or enhanced definition. "Standard" refers to it being the prevailing sp ...
content and
DVB-T2 DVB-T2 is an abbreviation for "Digital Video Broadcasting – Second Generation Terrestrial"; it is the extension of the television standard DVB-T, issued by the consortium DVB, devised for the broadcast transmission of digital terrestrial tele ...
for high definition content. The digital switchover process involved discontinuing analogue terrestrial TV broadcasts, which in some areas allowed for greater signal strength and/or better coverage of digital multiplexes. The process concluded on 24 October 2012, when digital switchover completed in Northern Ireland (the same day as the
Republic of Ireland Ireland ( ga, Éire ), also known as the Republic of Ireland (), is a country in north-western Europe consisting of 26 of the 32 counties of the island of Ireland. The capital and largest city is Dublin, on the eastern side of the island. A ...
also completed its digital switchover). In areas where analogue signals had terminated, older receiving equipment was likely to require replacement or upgrade. This process was subsidised by the UK Government for those on low incomes. Contracts for this operation were awarded to BSkyB in the Border Television region. Upgrading of analogue receiving equipment required a Freeview set-top box (or other DVB-T capable digital receiver). Where an analogue TV recording device was in use this ideally would require a separate Freeview set-top box, to replicate the previous functionality of recording and watching different programme sources.


History

The progress towards digital switchover in the UK was long. The then
Secretary of State for Culture, Media and Sport The secretary of state for digital, culture, media and sport, also referred to as the culture secretary, is a Secretary of State (United Kingdom), secretary of state in the Government of the United Kingdom, with overall responsibility for strateg ...
, Chris Smith, announced in 1999 that the Government's intention was to achieve switchover "between 2006 and 2010". Work started in earnest with the setting up of the Digital Action Plan, a body working across industry, government and consumer groups to advise on the best way to meet the switchover target date. By 2003, however, it was becoming clear that switchover could not start by 2006. In particular, the decision taken by the
International Telecommunication Union The International Telecommunication Union is a specialized agency of the United Nations responsible for many matters related to information and communication technologies. It was established on 17 May 1865 as the International Telegraph Unio ...
to call a Regional Radiocommunication Conference to establish a
frequency plan A frequency plan, bandplan, band plan or wavelength plan is a plan for using a particular band of radio frequencies, that are a portion of the electromagnetic spectrum. Each frequency plan defines the frequency range to be included, how channels a ...
for digital broadcasting meant that in practice, substantive steps towards switchover would need to wait until after the conference's second session, due to be held in May and June 2006. On 15 September 2005, addressing the
Royal Television Society The Royal Television Society (RTS) is a British-based educational charity for the discussion, and analysis of television in all its forms, past, present, and future. It is the oldest television society in the world. It currently has fourteen r ...
in
Cambridge Cambridge ( ) is a university city and the county town in Cambridgeshire, England. It is located on the River Cam approximately north of London. As of the 2021 United Kingdom census, the population of Cambridge was 145,700. Cambridge bec ...
, Smith's successor at the DCMS,
Tessa Jowell Tessa Jane Helen Douglas Jowell, Baroness Jowell, (; 18 September 1947 – 12 May 2018) was a British Labour Party politician and life peer who served as the Member of Parliament (MP) for Dulwich and West Norwood, previously Dulwich, from 199 ...
, announced the go-ahead for switchover in the UK, coupled with support measures to ensure the disadvantaged are not left behind. On the day after Jowell's speech, an independent not-for-profit company,
Digital UK Digital UK is a British television communications company owned by the BBC (1922), ITV (TV network), ITV (1955), Channel 4 (1982) and Channel 5 (British TV channel), Channel 5 (1997) which supports Freeview (UK), Freeview viewers and channels. ...
, was established to co-ordinate the switchover process. Set up by the broadcasters and the commercial multiplex operators, Digital UK was required to co-ordinate the project and ensure that the public are kept informed about progress. Local television broadcasters, including the BBC and ITV, actively encouraged viewers to upgrade to digital television. UK broadcasters were also under additional pressure to complete migration before the
Olympic Games The modern Olympic Games or Olympics (french: link=no, Jeux olympiques) are the leading international sporting events featuring summer and winter sports competitions in which thousands of athletes from around the world participate in a var ...
.


Digital rollout

The British Government gave
Ofcom The Office of Communications, commonly known as Ofcom, is the government-approved regulatory and competition authority for the broadcasting, telecommunications and postal industries of the United Kingdom. Ofcom has wide-ranging powers acros ...
and
Digital UK Digital UK is a British television communications company owned by the BBC (1922), ITV (TV network), ITV (1955), Channel 4 (1982) and Channel 5 (British TV channel), Channel 5 (1997) which supports Freeview (UK), Freeview viewers and channels. ...
jointly the task of discontinuing analogue television broadcasting. The switch-off occurred on an ITV sub-region basis. In March 2005, a technical trial in
Ferryside Ferryside ( cy, Glan-y-fferi) is a village in the community of St Ishmael, Carmarthenshire, Wales. It is south of Carmarthen near the mouth of the River Tywi. Originally a ferry crossing, then becoming a fishing village, it has developed as a ...
, Wales, resulted in viewers losing three out of the four available analogue channels in favour of going digital, leaving only analogue BBC Two Wales until switchover at
Preseli Preseli Pembrokeshire (, ; cy, Preseli Sir Benfro) was one of six local government districts of Dyfed in West Wales from 1974 to 1996. Until 1987 the name of the district was Preseli. The district took its name from the Preseli Hills. Creation Th ...
in August 2009 (at the time, BBC 2W on digital offered a different schedule to BBC Two Wales on analogue). In October 2007, following a 15-month publicity and information campaign, and an early digital launch in August by Channel 5, the Whitehaven, Eskdale Green and Gosforth transmitters switched off analogue signals on the BBC Two frequency, and began broadcasting a temporary digital service for the main channels. On 14 November, all analogue signals were switched off, and the permanent three-multiplex digital service began (albeit with Channel 5 only on the Whitehaven transmitter, until 2009). Unfortunately, as had been feared, a small number of homes among the hills, which had received "fuzzy" analogue signals, particularly in Eskdale, were unable to receive a decodable Freeview signal. The only other serious problem resulted from the "rescan" command in some models of set-top box defaulting to frequencies used by the nearest main transmitter, instead of the strongest digital signals; this could be overcome by using the "add channel" option to select channels one-by-one, and in the long term by corrections to the boxes' software. In November 2008, the full rolling programme started in the
ITV Border ITV Border, previously Border Television and commonly referred to as simply Border, is the Channel 3 service provided by ITV Broadcasting Limited for the England/Scotland border region, covering most of Cumbria, Dumfries and Galloway, the S ...
region at the Selkirk transmitter, with the Caldbeck transmitter switching a year later (Caldbeck was rebuilt, and broadcasts Scottish multiplexes as well as English ones to improve service to viewers north of the border; the nearby Sandale transmitter ceased to broadcast TV). The programme continued across the rest of the country, with the
Westcountry The West Country (occasionally Westcountry) is a loosely defined area of South West England, usually taken to include all, some, or parts of the counties of Cornwall, Devon, Dorset, Somerset, Bristol, and, less commonly, Wiltshire, Gloucesters ...
region,
Wales Wales ( cy, Cymru ) is a Countries of the United Kingdom, country that is part of the United Kingdom. It is bordered by England to the Wales–England border, east, the Irish Sea to the north and west, the Celtic Sea to the south west and the ...
and the
Granada Granada (,, DIN 31635, DIN: ; grc, Ἐλιβύργη, Elibýrgē; la, Illiberis or . ) is the capital city of the province of Granada, in the autonomous communities of Spain, autonomous community of Andalusia, Spain. Granada is located at the fo ...
region switching over in 2009. The
West West or Occident is one of the four cardinal directions or points of the compass. It is the opposite direction from east and is the direction in which the Sunset, Sun sets on the Earth. Etymology The word "west" is a Germanic languages, German ...
, STV North,
STV Central Scottish Television (now, legally, known as STV Central Limited) is the ITV network franchisee for Central Scotland. The channel — the largest of the three ITV franchises in Scotland — has been in operation since 31 August 1957 and is the ...
regions and the
Channel Islands The Channel Islands ( nrf, Îles d'la Manche; french: îles Anglo-Normandes or ''îles de la Manche'') are an archipelago in the English Channel, off the French coast of Normandy. They include two Crown Dependencies: the Bailiwick of Jersey, ...
followed in 2010; the
Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...
,
Yorkshire Yorkshire ( ; abbreviated Yorks), formally known as the County of York, is a Historic counties of England, historic county in northern England and by far the largest in the United Kingdom. Because of its large area in comparison with other Eng ...
and Anglia regions in 2011; and finally the
Meridian Meridian or a meridian line (from Latin ''meridies'' via Old French ''meridiane'', meaning “midday”) may refer to Science * Meridian (astronomy), imaginary circle in a plane perpendicular to the planes of the celestial equator and horizon * ...
,
London London is the capital and largest city of England and the United Kingdom, with a population of just under 9 million. It stands on the River Thames in south-east England at the head of a estuary down to the North Sea, and has been a majo ...
, Tyne Tees & UTV regions in 2012. Many decisions had to be made, including what to do about people who may find the new technology confusing, or who have no desire to receive more than the four or five channels they originally had, and who may have been reluctant to buy a digital box to view the free channels. The government arranged for the BBC to administer a Digital Switchover Help Scheme to ensure that groups such as the over-75s and recipients of disability benefits did not lose their television services when analogue transmissions were switched off. Another issue was that the "98.5 per cent of the population" availability target could only be achieved "via rooftop aerials", while Section 134 of the Communications Act 2003 sets out the principle "that no person should unreasonably be denied access to an electronic communications network or to electronic communications services". This is taken to mean that everyone has the right to mount a television aerial on their roof. Ofcom allocated frequencies for groups of households to provide "self-help" relay transmitters at their own expense (for analogue broadcasts there were some 200 of these, serving around 13,000 households), but suggested that in such cases, terrestrial TV may no longer be the most cost-effective solution.


The switchover process

After several months of press publicity, leaflet drops, public meetings etc., captions started appearing on analogue broadcasts from the affected transmitters, warning viewers that the analogue service would shortly be switched off and that they would need to take action (for Whitehaven, the first large area to switch over, the captions started appearing some 5 months before the BBC Two analogue service was switched off ). At about the same time, details of the Switchover Help Scheme were distributed. Although viewers who lived outside existing Freeview reception areas were unable to test any digital receiving equipment they had bought at this early stage, test-screens on
Ceefax Ceefax (, punning on "seeing facts") was the world's first teletext information service and a forerunner to the current BBC Red Button service. Ceefax was started by the BBC in 1974 and ended, after 38 years of broadcasting, at 23:32:19 BST ( ...
(BBC One & Two) and
Teletext A British Ceefax football index page from October 2009, showing the three-digit page numbers for a variety of football news stories Teletext, or broadcast teletext, is a standard for displaying text and rudimentary graphics on suitably equipp ...
(ITV & C4/S4C) page 284 made it possible to determine whether they were likely to need a new aerial or a signal amplifier to receive digital transmissions. Next, detailed information booklets were delivered to all households in the area (including many on the fringe who may have been receiving their TV from other transmitters- hence the importance of the on-screen warning captions). Two or three months later, the first stage of the switchover began with the analogue
BBC Two BBC Two is a British free-to-air public broadcast television network owned and operated by the BBC. It covers a wide range of subject matter, with a remit "to broadcast programmes of depth and substance" in contrast to the more mainstream an ...
replaced with the new BBC A multiplex. At some locations, during the period between stage one and stage two, BBC One, ITV or Channel 4 moved to the analogue BBC Two frequency where that channel's frequency was required for the digital transmission of Multiplex 1. At the same time, captions appeared on the remaining analogue channels reminding viewers of the impending switchover. Finally, the second stage saw the remaining analogue transmissions switched off and the other high power multiplexes switched on. Initially, this occurred four weeks after stage one, but starting with the switchover at
Mendip Mendip may refer to: *Mendip District, a local government district of Somerset, England * Mendip Hills, a group of hills in Somerset, England ** Mendip Way, a footpath across the Mendip Hills **Mendip TV Mast, a transmitter in the Mendips area *For ...
in April 2010 onwards, this gap was reduced to two weeks. Three multiplexes (BBC A, D3&4, BBC B) are for
public service broadcasting Public broadcasting involves radio, television and other electronic media outlets whose primary mission is public service. Public broadcasters receive funding from diverse sources including license fees, individual contributions, public financing ...
and are broadcast from all transmitter sites. They contain around 25 TV channels, half a dozen radio stations and half a dozen text/interactive services. These include all the television channels from the BBC, some from ITV and Channel 4, Channel 5 and S4C (in Wales only). The other three multiplexes (SDN, Arqiva A, Arqiva B) are broadcast from main transmitter sites only and are operated by their respective commercial licence-holders. To reflect the slightly changed roles, the multiplex names were also changed:


Post-switchover

The adoption of the technically superior
DVB-T DVB-T, short for Digital Video Broadcasting – Terrestrial, is the DVB European-based consortium standard for the broadcast transmission of digital terrestrial television that was first published in 1997 and first broadcast in Singapore in Febr ...
format occurred in each region at the date of switchover. This resulted in no reception for viewers with older '2k' only equipment, such as former ONdigital/ITV Digital boxes, and other incompatible IDTVs and set top boxes. In the Meridian and Anglia regions, transmitters formed a
single-frequency network A single-frequency network or SFN is a broadcast network where several transmitters simultaneously send the same signal over the same frequency channel. Analog AM and FM radio broadcast networks as well as digital broadcast networks can operate ...
when they were converted to all-digital operation. Alternative post-switchover multiplex designations were used on internal documentation by the BBC switchover contractor Arqiva, but changing the designations of the multiplexes requires changes to legislation and to the multiplex licences issued by Ofcom and is not in the current draft. When digital switchover was complete, two new sub-bands of the UHF spectrum were clear (frequencies corresponding to channel ranges 31–40 and 63–69), leaving only channels 21–30 and 41–62 for digital television multiplexes. This "
digital dividend The digital dividend refers to the radio spectrum which is released in the process of digital television transition. When television broadcasters switch from analog TV to digital-only platforms, part of the electromagnetic spectrum that has b ...
" required millions of homes to upgrade their aerials to the wideband type to receive some or all of the Freeview multiplexes. This spectrum is useful because of its trade-off between bandwidth and range. Following a consultation, in September 2011 Ofcom stated that an auction for the 600 MHz band will most likely lead to channels 31–37 being used for three new TV multiplexes; a reference transmission plan assumes two frequencies would be multiple-frequency networks, and channel 36 would be used as a national single-frequency network. The remaining reallocated frequencies can be re-used for other services, for example the provision of: * Mobile Television services * wireless (mobile) broadband services * wider coverage for advanced services in remote and rural areas * more multiplexes carrying more channels * high definition (HD) services The clearing and re-allocation of these channels of the spectrum for other services caused some controversy within technical industries, such as
wireless microphones A wireless microphone, or cordless microphone, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated. Also known as a radio microphone, it has a small, battery- ...
, as Ofcom decided to clear channel 69 (854–862 MHz) to match the rest of Europe and make the facilitation of future services easier. Further re-allocations of the other freed analogue television channels have not yet occurred, but when implemented will require legislation changes. It is likely that if they are sold commercially, they will not only attract interest, but may be bought for millions of pounds due to the high demand for spectrum throughout most of Europe. Ofcom have published further information about the auctioned channel in a
announcement
on their website. OFCOM released their consultation of the future of the 600 MHz and 700 MHz UHF bands beyond 2018 on 16 November 2012. This document recommends that the 600 MHz UHF band is allocated to DVB-T2 MPEG-4 Freeview HD services and Whitespace services, allowing a future migration of the existing 700 MHz Freeview allocation to 700 MHz mobile data services (synchronising the bandwidth usage with many other markets in Europe and globally).


Digit Al

Digit Al is a robot character created for Digital UK in 2005, by Abbott Mead Vickers BBDO and voiced by the English comedy actor
Matt Lucas Matthew Richard Lucas (born 5 March 1974) is an English actor, comedian, writer, and television presenter. He is best known for his work with David Walliams on the BBC sketch comedy series '' Little Britain'' (2003–2006, 2020) and '' Come Fly ...
, used in material publicising the digital switchover. It appeared in the public information programme run by
Digital UK Digital UK is a British television communications company owned by the BBC (1922), ITV (TV network), ITV (1955), Channel 4 (1982) and Channel 5 (British TV channel), Channel 5 (1997) which supports Freeview (UK), Freeview viewers and channels. ...
until 2012. The character was first transmitted simultaneously on about 100 television channels and on regional BBC television on 5 May 2006.


Digital Self-Help Relays

Terrestrial analogue relay stations have been repeating TV signals to areas not covered by broadcaster-owned transmitters since the
Independent Broadcasting Authority The Independent Broadcasting Authority (IBA) was the regulatory body in the United Kingdom for commercial television (ITV and Channel 4 and limited satellite television regulation – cable television was the responsibility of the Cable Authorit ...
started licensing them in 1980. Recently self-help groups have had to look into upgrading their old analogue transmitters to digital ones. The first digital self-help relay was installed at Ladram Bay, Devon by Stuart Harse and Liam Kelly (broadcast engineers from Bristol). The system was designed by Mike Rea of Taylor Transmitters, Oldham UK. The Ladram Bay TV repeater broadcasts all six mux signals from the Stockland Hill transmitter.


Post-switchover reorganisation and HD

In March 2006, the development of a new second generation digital terrestrial broadcasting standard,
DVB-T2 DVB-T2 is an abbreviation for "Digital Video Broadcasting – Second Generation Terrestrial"; it is the extension of the television standard DVB-T, issued by the consortium DVB, devised for the broadcast transmission of digital terrestrial tele ...
, was agreed by the
DVB Digital Video Broadcasting (DVB) is a set of international open standards for digital television. DVB standards are maintained by the DVB Project, an international industry consortium, and are published by a Joint Technical Committee (JTC) o ...
Group. The BBC, ITV, Channel 4, S4C and Channel 5 agreed with the regulator
Ofcom The Office of Communications, commonly known as Ofcom, is the government-approved regulatory and competition authority for the broadcasting, telecommunications and postal industries of the United Kingdom. Ofcom has wide-ranging powers acros ...
to convert one UK multiplex (B, or PSB3) to DVB-T2 to increase capacity for
HDTV High-definition television (HD or HDTV) describes a television system which provides a substantially higher image resolution than the previous generation of technologies. The term has been used since 1936; in more recent times, it refers to the g ...
(High Definition Television) via DTT. The first TV region to use the new standard was
Granada Granada (,, DIN 31635, DIN: ; grc, Ἐλιβύργη, Elibýrgē; la, Illiberis or . ) is the capital city of the province of Granada, in the autonomous communities of Spain, autonomous community of Andalusia, Spain. Granada is located at the fo ...
in November 2009 (with existing switched over regions being changed at the same time). It is expected that over time there will be enough DVB-T2 receivers sold to switch all DTT transmissions to DVB-T2, and
MPEG-4 Part 10 Advanced Video Coding (AVC), also referred to as H.264 or MPEG-4 Part 10, is a video compression standard based on block-oriented, motion-compensated coding. It is by far the most commonly used format for the recording, compression, and distr ...
. From 27 October 2009, Multiplex B (PSB3) was cleared of SD channels in post DSO areas, which were moved to Multiplex 1 (PSB1). In pre DSO areas, Multiplex B continued to carry BBC Four, BBC Parliament, CBeebies, BBC Radio Stations and 301 until DSO. Former streams of 302 and News Multiscreen on Multiplex B were sublet to broadcasters other than the BBC for pre DSO areas only, and were not available at all in post DSO areas because of the new DVB-T2 HD multiplex as replacement. On 3 April 2008, Ofcom published its final decision for the HDTV transmission format: DVB-T2 and MPEG-4. Initially there were to be three HD services available:
BBC HD BBC HD was a 24-hour high-definition television channel provided by the BBC. The service was initially run as a trial from 15 May 2006 until becoming a full service on 1 December 2007 before its discontinuation on 26 March 2013. It broadcast ...
,
ITV HD ITV1 HD is a British free-to-air high-definition public broadcast television network operated by ITV plc, the company which is contracted to provide 13 ITV1 services across the UK. ITV1 HD simulcasts them in high-definition (excluding former Ch ...
/ STV HD and Channel 4 HD/S4C Clirlun. Channel 5 HD was due to launch during 2010 but was unable to reach 'key criteria' to keep its slot. Spare allocation on multiplex B was handed over to the BBC, two years to the date when it was anticipated that further capacity on multiplex B would revert to the control of the BBC Trust. On 3 November 2010, BBC One HD launched on Freeview HD. It is available in addition to the existing BBC HD channel. During 2011,
Ofcom The Office of Communications, commonly known as Ofcom, is the government-approved regulatory and competition authority for the broadcasting, telecommunications and postal industries of the United Kingdom. Ofcom has wide-ranging powers acros ...
gave the Commercial Public Service Broadcasters another opportunity to apply to provide an additional HD service from 2012.


List of digital terrestrial channels


Multiplexing


The multiplexes

In 2014, Ofcom decided to reallocate the frequency band used by COM7 and COM8 to make it available for mobile communications. This project, known as "700Mhz clearance", was intended to be complete by the second quarter of 2020; the switch-off is largely complete but the remaining transmitter changes are postponed due to the
COVID-19 pandemic The COVID-19 pandemic, also known as the coronavirus pandemic, is an ongoing global pandemic of coronavirus disease 2019 (COVID-19) caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The novel virus was first identif ...
. Channels broadcast on the COM8 multiplex were cleared by Arqiva on 22 June 2020, with some services moving to broadcast from COM7 or PSB3.


Use of multiplexing technology

Each multiplex is an error-protected
bitstream A bitstream (or bit stream), also known as binary sequence, is a sequence of bits. A bytestream is a sequence of bytes. Typically, each byte is an 8-bit quantity, and so the term octet stream is sometimes used interchangeably. An octet may ...
of 24, 27 or 40 megabits per second, which can be used for almost any combination of digitally-encoded
video Video is an electronic medium for the recording, copying, playback, broadcasting, and display of moving visual media. Video was first developed for mechanical television systems, which were quickly replaced by cathode-ray tube (CRT) syste ...
,
audio Audio most commonly refers to sound, as it is transmitted in signal form. It may also refer to: Sound *Audio signal, an electrical representation of sound *Audio frequency, a frequency in the audio spectrum *Digital audio, representation of sound ...
and data. The DVB-T standard provides a multiplex service that can make trade-offs between the number of services and the picture and audio quality. * a number of services use the same
bandwidth Bandwidth commonly refers to: * Bandwidth (signal processing) or ''analog bandwidth'', ''frequency bandwidth'', or ''radio bandwidth'', a measure of the width of a frequency range * Bandwidth (computing), the rate of data transfer, bit rate or thr ...
at different times. For example,
CBeebies CBeebies is a British free-to-air public broadcast children's television channel owned and operated by the BBC. It is also the brand used for all BBC content for children aged 6 years and under. Its sister channel CBBC is aimed at older childr ...
and
BBC Four BBC Four is a British free-to-air public broadcast television channel owned and operated by the BBC. It was launched on 2 March 2002
currently use the same space in their multiplex, with CBeebies broadcasting from 6am until 7pm and BBC Four from 7pm. * some multiplexes allocate more bandwidth to services, providing a smaller number of higher-quality services. * The
modulation In electronics and telecommunications, modulation is the process of varying one or more properties of a periodic waveform, called the ''carrier signal'', with a separate signal called the ''modulation signal'' that typically contains informatio ...
of the multiplexes can be varied to squeeze higher digital
bitrate In telecommunications and computing, bit rate (bitrate or as a variable ''R'') is the number of bits that are conveyed or processed per unit of time. The bit rate is expressed in the unit bit per second (symbol: bit/s), often in conjunction w ...
s out of the same portion of the
electromagnetic spectrum The electromagnetic spectrum is the range of frequencies (the spectrum) of electromagnetic radiation and their respective wavelengths and photon energies. The electromagnetic spectrum covers electromagnetic waves with frequencies ranging from ...
, but require a stronger signal for good reception. The modulation schemes used in the UK are, in order of bandwidth efficiency, each with a progressively higher bitrate, at the cost of progressively higher likelihood of signal degradation: **
QPSK Phase-shift keying (PSK) is a digital modulation process which conveys data by changing (modulating) the phase of a constant frequency reference signal (the carrier wave). The modulation is accomplished by varying the sine and cosine inputs at a ...
(only used for tests in the Oxford and London areas) **
16-QAM Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signal ...
(no longer used as of digital switchover) **
64-QAM Quadrature amplitude modulation (QAM) is the name of a family of digital modulation methods and a related family of analog modulation methods widely used in modern telecommunications to transmit information. It conveys two analog message signal ...
(only used on the DVB-T multiplex) ** 256-QAM (only used on the DVB-T2 multiplex) ** 1024-QAM ** 2048-QAM (currently in development) :By late 2009, multiplexes 2 and A used 64-QAM and were consequently more prone to poor reception, while the other multiplexes used 16-QAM. At switchover the transmission mode was changed from 16-QAM to 64-QAM on Multiplex 1 (PSB1), increasing the effective bandwidth of the multiplex. The switch to 64-QAM mode also provided extra bandwidth on Multiplexes C (COM5) and D (COM6). :By late 2012, the digital switchover was complete, with all DVB-T multiplexes using 64-QAM. The switchover allowed the transmitters to broadcast at a higher power level, reducing the likelihood of reception errors when receiving 64-QAM encoded broadcasts. * Multiplexes can make use of
statistical multiplexing Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation (DBA). In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bitrate digital channels or ...
at the
MPEG The Moving Picture Experts Group (MPEG) is an alliance of working groups established jointly by International Organization for Standardization, ISO and International Electrotechnical Commission, IEC that sets standards for media coding, includ ...
video coder whereby the bitrate allocated to a channel within the multiplex can vary dynamically depending on how difficult it is to code the picture content at that precise time, and how much demand there is for bandwidth from other channels. In this way, complex pictures with much detail may demand a higher bitrate at one instant and this can result in the bitrate allocated to another channel in the same multiplex being reduced if the second channel is currently transmitting pictures which are easier to encode, with less fine detail.


Improvements in compression technology

Developments in
statistical multiplexing Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation (DBA). In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bitrate digital channels or ...
, improved compression technology, and, in some cases, an acceptance of lower quality or lower resolution broadcasts, allowed gradual increases in the number of services carried on digital terrestrial television multiplexes. As the number of homes receiving digital terrestrial grew, the interest in new channel capacity increased. In 2005, the auction for two new slots on National Grid Wireless multiplex D resulted in broadcasters bidding high prices to gain bandwidth. ITV won the bidding for the first slot (on which it launched
Men & Motors Men & Motors was a men's lifestyle television channel in the UK. It was the last remaining station operated by the former Granada Sky Broadcasting joint venture, set up by Granada Television (now part of ITV plc) and satellite broadcaster Briti ...
on 2 May 2005, replaced by ITV Play and later ITV2+1), and Channel 4 the second. Channel 4 launched E4 +1 (not its new channel
More4 More4 is a British free-to-air television channel, owned by Channel Four Television Corporation. The channel launched on 10 October 2005. Its programming mainly focuses on lifestyle and documentaries, as well as foreign dramas. Content When ...
) on the multiplex when the slot became available on 1 June (E4 launched on Freeview on 27 May 2005). National Grid Wireless made an additional new slot available on Multiplex D using the new compression techniques. The 18-hour channel, running from 6am to midnight, became available on 1 December 2005. Companies interested had until 1 November to submit their bids, with bids said to have reached £10 million, from an entry level of £5.5 million, with 12 separate bidders covering all sectors of broadcasting. This slot was won by
Channel 4 Channel 4 is a British free-to-air public broadcast television network operated by the state-owned enterprise, state-owned Channel Four Television Corporation. It began its transmission on 2 November 1982 and was established to provide a four ...
; it was occupied by
More4 More4 is a British free-to-air television channel, owned by Channel Four Television Corporation. The channel launched on 10 October 2005. Its programming mainly focuses on lifestyle and documentaries, as well as foreign dramas. Content When ...
+1 until live coverage of Big Brother replaced it on 18 May 2006.
Film4 Film4 is a British free-to-air television network owned by Channel Four Television Corporation launched on 1 November 1998, devoted to broadcasting films. While its standard-definition channel is available on Freeview and Freesat platforms, i ...
took over the slot 23 July 2006. Later compression technology, implemented in
codec A codec is a device or computer program that encodes or decodes a data stream or signal. ''Codec'' is a portmanteau of coder/decoder. In electronic communications, an endec is a device that acts as both an encoder and a decoder on a signal or da ...
s like MPEG4,
H.264 Advanced Video Coding (AVC), also referred to as H.264 or MPEG-4 Part 10, is a video compression standard based on block-oriented, motion-compensated coding. It is by far the most commonly used format for the recording, compression, and distr ...
or
VC-1 SMPTE 421, informally known as VC-1, is a video coding format. Most of it was initially developed as Microsoft's proprietary video format Windows Media Video 9 in 2003. With some enhancements including the development of a new Advanced Profile, ...
, can enable a substantial increase in either quality or capacity due to their increased efficiency, but use of such technologies would again require most viewers to purchase new reception equipment, since the vast majority of standard set-top boxes support only the older
MPEG2 MPEG-2 (a.k.a. H.222/H.262 as was defined by the ITU) is a standard for "the generic coding of moving pictures and associated audio information". It describes a combination of lossy video compression and lossy audio data compression methods, w ...
encoding. BSkyB were the first to suggest such a move to increase the number of channels available within their own share of space using MPEG4 on a subscription service. However, BSkyB's proposals were ultimately shelved following regulatory delays. The BBC, which ultimately broadcast high-definition television on Freeview in the DVB-T2 format adopted in 2009, initially considered an alternative method utilising spare capacity at night to allow the download of high definition programmes for later replay. In addition the BBC's Research and Development team invented a transmission method that doubles the effective bandwidth that could currently be delivered by each multiplex using "spatial multiplexing". While conventional analogue and digital terrestrial television signals are transmitted either vertically or horizontally polarised (providing protection against interference from other distant signals which may be transmitted on the same frequency, but will usually be planned to use the opposite polarisation), the proposed technique would have involved using the same frequency to transmit two different signals at once, one vertically and one horizontally polarised. A special receiving aerial, containing both vertically and horizontally polarised elements, could receive both signals simultaneously and feed these to a suitable set top box, but would require new transmitters and receiving equipment and aerials; the technique was ultimately not adopted.


See also

*
Digital television in the United Kingdom There are four major forms of digital television (DTV) broadcast in the United Kingdom: a direct-to-home satellite service from the Astra 28.2°E satellites provided by Sky UK, a cable television service provided by Virgin Media (known as Virgi ...
*
Top Up TV Top Up TV was a pay TV service in the United Kingdom which launched in March 2004, operating on the digital terrestrial television platform. The aim of the service was to "top up" Freeview customers by providing additional content and service ...
*
BT TV BT TV is a subscription IPTV service offered by BT; a division of United Kingdom telecommunications company BT Group, and was originally launched as BT Vision in December 2006. As of the end of June 2019, BT TV had 1.9 million customers. ...
*
Freesat Freesat is a British free-to-air satellite television service, first formed as a joint venture between the BBC and ITV plc and now owned by Digital UK. The service was formed as a memorandum in 2007 and has been marketed since 6 May 2008. Free ...
*
High-definition television in the United Kingdom High-definition television in the United Kingdom is available via cable, IPTV, satellite and terrestrial television. The first high-definition broadcasts began in late 2005 and since then the number of channels available to view has grown to a m ...
* List of British television channels


References


External links


Official sites


Digital Switchover UK

BBC – Digital – Homepage

BBC – Digital – Switchover

Freeview official site

Top Up TV

DigitalUK


* ttp://www.ricability-digitaltv.org.uk/ Digital TV Consumer test reportsUK Government-funded website to support Digital Switchover


Other sites


Details of all UK digital transmitters







How to Find Your Local UK Transmitter
{{DEFAULTSORT:Digital Terrestrial Television In The United Kingdom Digital television in the United Kingdom Lists of British television channels Telecommunications-related introductions in 1998