Digital terrestrial television in the United Kingdom
Encyclopedia
Digital terrestrial television in the United Kingdom
encompasses over 100 television, radio and interactive services broadcast via the UK's terrestrial television network and receivable with a standard television aerial. The majority of services, including those from the existing five analogue broadcasters, are broadcast free-to-air, and a further selection of encrypted Pay-TV services (such as ESPN) are also available.
Digital Terrestrial services are often referred to with the Freeview name, however this is only a brand name adopted by the broadcasters of free-to-air services. Freeview channels account for most, although not all, of the total available channels broadcast on digital terrestrial television, available at no extra cost and requiring no subscription other than payment of the annual TV licence fee.
The digital broadcasting technology adopted in the UK is the DVB-T
system (Digital Video Broadcasting – Terrestrial) carrying compressed digital audio, video and other data in a combined transport stream, using COFDM modulation. A total of six 'multiplexes' are broadcast in the UK, guaranteed to reach over 90% of the country when analogue signals are fully switched off. Three of the six multiplexes, carrying the free public service channels operated by the BBC
, ITV
, Channel 4
, S4C
and Channel 5, are guaranteed wider coverage still, reaching 98.5% of the country including areas dependent on low-power local relays.
or Integrated Digital Television
(IDTV), connected to an appropriate receiving antenna. In most cases, reception is possible using existing 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' VCR or DVD recorder, or by the use of newer models of such recorders which have built-in digital tuners. Alternatively, an increasingly common option is by the use of set-top-boxes which incorporate a hard disc drive, and allow the recording of the digital signal directly to disc, for later replay. Recording on such boxes, known as Personal Video Recorders
or PVRs, is often 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 Vision
, and TalkTalk TV, 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
and Windows Media Center
. Most cards or tuners include their own software in the package also.
. A number of interactive services including a newer version of Teletext
is also offered.
An eight-day Electronic Programme Guide (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
service, will only display details of 'now and next' programme information.
A fourteen-day Top Up TV
EPG is an alternative which is available to TUTV-branded PVRs.
es (abbreviated to 'mux') labelled 1, 2, A, B, C, and D.
The Independent Television Commission
(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.
) and Channel 5 and S4C
shared Multiplex A. The remaining spectrum (Muliplexes B, C and D) was then auctioned off. A consortium made up of Granada and Carlton
(members of the ITV network, which have now merged to form ITV plc
) and BSkyB
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
(which had started on 23 September 1998 with four national variations), BBC News 24
and BBC Parliament
(albeit in sound only). ITV initially used their space to house ITV2
(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
during the early mornings. Channel 4 used their space for subscription channels FilmFour
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
(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
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
outside of 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.
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
. 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
, an insecure hackable
encryption
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.
, transmitter company National Grid Wireless (known at the time as Crown Castle UK) and BSkyB. This consortium (legal name DTV Services Ltd and trading under the "Freeview" brand) won and launched a new service. Dropping the ITV Digital failed 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 operates 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
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.
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
and Northern Ireland
from the multiplex owner, SDN, but rents from Sit-up Ltd
in Wales
, timesharing with bid tv
. 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 on Multiplex 2 for its own services More 4, E4, and most recently Film4
.
In October 2006, Channel 5 launched two new free-to-air digital channels, Five Life
and Five US
, 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 (PVR). At the same time, they started reducing the linear service.
On 19 April 2006, Ofcom ruled that, on request of each multiplex
operator, the 'free-to-air
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 16QAM 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
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) codec, which would enable a greater numbner 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.
Affected models are:
Some other models and televisions also require an over-air download for correct operation.
will completely replace analogue terrestrial television in the United Kingdom
, the Isle of Man
by 2012, and the Channel Islands
by 2010. This process is known as "Digital Switchover", or DSO. The Digital TV Group
the industry association for digital television in the UK, is responsible for co-ordination between Freeview and other digital services. DTG licences suitable equipment to bear the Digital Tick and Freeview Playback Logos to identify PVRs and digital TV services designed to work through switchover, and to raise awareness of DTT product quality and standards. Digital terrestrial television is broadcast using the DVB-T
international standard.
The Digital Switchover process is already underway in parts of the UK, and it involves discontinuing analogue terrestrial TV broadcasts. In some areas this will allow greater signal strength and/or better coverage of digital multiplexes.
In areas where analogue signals have been terminated, older receiving equipment is likely to require replacement or upgrade. This process is being subsidised by the UK Government for those on low incomes. Current contracts for this operation have been awarded to BSkyB in the Borders region. Upgrading of analogue receiving equipment requires a Freeview set-top box (or other digital receiver). Where an analogue TV recording device is in use ideally this will be provided with a separate Freeview set-top box, to replicate existing functionality of recording and watching different programme sources.
, 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
to call a Regional Radiocommunication Conference to establish a frequency plan 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 & June 2006.
On 15 September 2005, addressing the Royal Television Society
in Cambridge
, Smith's successor at the DCMS
, Tessa Jowell
, announced the go-ahead for switchover in the UK, coupled with support measures to ensure the disadvantaged are not left behind.
In essence, the UK will switchover on a regional basis, starting in Whitehaven
on the 17 October 2007, then the rest of the Border Television
region in the second half of 2008, and then finishing in London in 2012. Local television broadcasters, including the BBC
and ITV
, are actively encouraging viewers to upgrade to digital television. UK broadcasters are also under additional pressure to complete migration since London will be hosting the Olympic Games in 2012.
On the day after Jowell's speech, an independent. not-for-profit company, Digital UK
, was established to coordinate the switchover process. Set up by the broadcasters and the commercial multiplex operators, Digital UK is required to co-ordinate the project and ensure that the public are kept informed about progress.
and Digital UK
jointly the task of discontinuing analogue television broadcasting. The switch-off will occur on an ITV sub-region basis. A technical trial in Ferryside, Wales, resulted in viewers voting to lose three out of the four available analogue channels in favour of going digital, so the unwanted analogue signals were switched off at the end of March 2005. 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 with the ITV Border
Selkirk region, then Caldbeck (which is being rebuilt, and will broadcast both England and Scotland multiplexes to improve service to viewers north of the border; the nearby Sandale transmitter will cease to broadcast TV), ITV Westcountry
Beacon Hill, Stockland Hill, Huntshaw Cross, Redruth, Caradon Hill, Wales
Preseli, Carmel, ITV Granada
whole region, Wales Llanddona, Moel-Y-Parc, Blaenplwyf, Long Mountain, Wenvoe then the rest of the UK: ITV West, STV North
and Channel Television
in 2010; STV Central
from 2010–11; ITV Central
, ITV Yorkshire
and ITV Anglia
in 2011; and finally ITV Meridian
, ITV London
, ITV Tyne Tees
& UTV
in 2012.
Many decisions must 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 presently have, and who may be reluctant to buy a digital box in order to view the free channels. The government has 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 will not lose their television services when analogue transmissions are switched off.
Another issue is that the "98.5 per cent of the population" availability target can 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 will allocate frequencies for groups of households to provide "self-help" relay transmitters at their own expense (for analogue broadcasts there are some 200 of these, serving around 13,000 households), but suggests that in such cases, terrestrial TV may no longer be the most cost-effective solution.
Landlords of communal housing are likely to have to upgrade old master aerial TV distribution systems. A new alternative, the integrated reception system
is being promoted as a way to offer the full range of terrestrial and satellite broadcasts from a single aerial cluster; however, residents are likely to be asked to pay substantially higher annual charges when such a system is installed.
(BBC One & Two) and Teletext
(ITV & C4/S4C) page 284 make it possible to determine whether they are likely to need a new aerial or a signal amplifier to receive digital transmissions.
Next, detailed information booklets will be delivered to all households in the area (including many on the fringe who may be receiving their TV from other transmitters- hence the importance of the on-screen warning captions). Two or three months later, the analogue BBC Two
signal will be replaced with Multiplex 1. At the same time, captions will appear on the remaining analogue channels reminding viewers of the impending switchover. Finally, four weeks later, the remaining analogue transmissions will be switched off, with the analogue ITV signal being replaced with Multiplex 2, and the analogue BBC One
signal with Multiplex B. At some locations, during the four-week switchover period, BBC One, ITV or Channel 4 will move to the analogue BBC Two frequency where that channel's frequency is required for the digital transmission of Multiplex 1.
Three multiplexes (current multiplexes 1, 2 and B) will be for public service broadcasting
and contain around 25 TV channels, including all the television channels from the BBC, ITV (except ITV2+1), Channel 4 (except Film4 and E4+1), S4C and Channel 5 (except 5 USA and 5*), half a dozen radio stations and half a dozen text/interactive services. The other three multiplexes (A, C and D) will continue to be operated by their respective commercial licence-holders. To reflect the slightly changed roles, the multiplex names will change:
In the Meridian and Anglia regions, transmitters will form a Single Frequency Network when they are converted to all digital operation.
Alternative post-switchover multiplex designations have been used on internal documentation by the BBC switchover contractor Arqiva, however 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 is complete, two new sub-bands of the UHF
spectrum will be clear (frequencies corresponding to channel ranges 31-40 and 62 to 69), leaving only channels 21-30 and 41-62 for digital television multiplexes. This "digital dividend" will require 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 600 MHz spectrum 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:
The clearing and re-allocation of these channels of the spectrum for other services has caused some controversy within technical industries, as Telecoms govorning body OfCom decided to clear Channel 69 (854-862MHz) in order to match the rest of Europe and make the facilitation of future services easier.. (For more information see Wireless Microphones
)
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 an announcement on their website.
, used in material publicising the digital switchover. He will appear in the public information programme run by Digital UK
until 2012. The character was first transmitted simultaneously on about 100 television channels and on regional BBC television on 5 May 2006.
, was agreed by the DVB Group. It is expected that it will be finalised during 2008, ready for deployment in 2009.
The BBC
, ITV
, Channel 4
S4C
and Channel 5 agreed with the regulator Ofcom
to convert one UK multiplex (B, or PSB3) to DVB-T2 to increase capacity for HDTV (High Definition Television) via DTT. They expect the first TV region to use the new standard will be Granada
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.
From 27 October 2009, Multiplex B (PSB 3) was cleared of SD channels in post DSO areas. Multiplex B in pre DSO areas will carry BBC Four, BBC Parliament, CBeebies, BBC Radio Stations, 301 until DSO where they will move to Multiplex 1 (PSB1). Former streams of 302 and News Multiscreen on Multiplex B are to sublet to other broadcasters than the BBC for pre DSO areas only, and not available at all in post DSO because of the new DVB-T2 HD multiplex as replacement. At this time, Community Channel is the only broadcaster using these streams.
Ofcom recently published its final decision for HDTV using DVB-T2 and MPEG-4: BBC HD
, ITV1 HD, Channel 4 HD
/S4C Clirlun
will each have one slot from launch. 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 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
intends to give the Commercial Public Service Broadcasters another opportunity to apply to provide an additional HD service from 2012.
* Pay TV service
of 18 or 24 megabits per second, which can be used for almost any combination of digitally-encoded video, audio
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.
, improved compression technology, and, in some cases, an acceptance of lower quality or lower resolution broadcasts, has allowed gradual increases in the number of services carried on digital terrestrial television multiplexes.
As the number of homes receiving digital terrestrial grows, the interest in new channel capacity has similarly 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
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
) 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
; it was occupied by More4+1
until live coverage of Big Brother replaced it on 18 May 2006. Film4
took over the slot 23 July 2006.
More recent compression technology, as now available in codec
s like MPEG4, H.264 or Microsoft's WMV could enable a substantial increase in either quality or capacity due to their increased efficiency. 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, who are now broadcasting high-definition television
on Freeview in the new DVB-T2 format, 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 polarised, 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. However, this would have required new transmitters and aerials, as well as new receiving equipment, and the technique was ultimately not adopted.
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
encompasses over 100 television, radio and interactive services broadcast via the UK's terrestrial television network and receivable with a standard television aerial. The majority of services, including those from the existing five analogue broadcasters, are broadcast free-to-air, and a further selection of encrypted Pay-TV services (such as ESPN) are also available.
Digital Terrestrial services are often referred to with the Freeview name, however this is only a brand name adopted by the broadcasters of free-to-air services. Freeview channels account for most, although not all, of the total available channels broadcast on digital terrestrial television, available at no extra cost and requiring no subscription other than payment of the annual TV licence fee.
The digital broadcasting technology adopted in the UK is the DVB-T
DVB-T
DVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it 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 the UK in 1998...
system (Digital Video Broadcasting – Terrestrial) carrying compressed digital audio, video and other data in a combined transport stream, using COFDM modulation. A total of six 'multiplexes' are broadcast in the UK, guaranteed to reach over 90% of the country when analogue signals are fully switched off. Three of the six multiplexes, carrying the free public service channels operated by the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
, ITV
ITV
ITV is the major commercial public service TV network in the United Kingdom. Launched in 1955 under the auspices of the Independent Television Authority to provide competition to the BBC, it is also the oldest commercial network in the UK...
, Channel 4
Channel 4
Channel 4 is a British public-service television broadcaster which began working on 2 November 1982. Although largely commercially self-funded, it is ultimately publicly owned; originally a subsidiary of the Independent Broadcasting Authority , the station is now owned and operated by the Channel...
, S4C
S4C
S4C , currently branded as S4/C, is a Welsh television channel broadcast from the capital, Cardiff. The first television channel to be aimed specifically at a Welsh-speaking audience, it is the fifth oldest British television channel .The channel - initially broadcast on...
and Channel 5, are guaranteed wider coverage still, reaching 98.5% of the country including areas dependent on low-power local relays.
Receiving and Recording
Digital Terrestrial Television is most commonly received by means of a compatible Set-top boxSet-top box
A set-top box or set-top unit is an information appliance device that generally contains a tuner and connects to a television set and an external source of signal, turning the signal into content which is then displayed on the television screen or other display device.-History:Before the...
or Integrated Digital Television
Integrated Digital Television
An Integrated Digital Television set is a television set with a built in digital tuner, be it for DVB-T, DVB-S, DVB-C, DMB-T/H, ATSC or ISDB. Most of them also allow reception of analogue signals . They do away with the need for a set top box for converting those signals for reception on a...
(IDTV), connected to an appropriate receiving antenna. In most cases, reception is possible using existing 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' VCR or DVD recorder, or by the use of newer models of such recorders which have built-in digital tuners. Alternatively, an increasingly common option is by the use of set-top-boxes which incorporate a hard disc drive, and allow the recording of the digital signal directly to disc, for later replay. Recording on such boxes, known as Personal Video Recorders
Digital video recorder
A digital video recorder , sometimes referred to by the merchandising term personal video recorder , is a consumer electronics device or application software that records video in a digital format to a disk drive, USB flash drive, SD memory card or other local or networked mass storage device...
or PVRs, is often 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 Vision
BT Vision
BT Vision is a hybrid IPTV-digital terrestrial television service provided by BT Group in the United Kingdom which was launched in December 2006...
, and TalkTalk TV, 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
MythTV is a free and open source home entertainment application with a simplified "10-foot user interface" design for the living-room TV, and turns a computer with the necessary hardware into a network streaming digital video recorder, a digital multimedia home entertainment system, or home theater...
and Windows Media Center
Windows Media Center
Windows Media Center is a digital video recorder and media player developed by Microsoft. It is an application that allows users to view and record live television, as well as organize and play music and videos...
. 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, including 16:9 anamorphic widescreenAnamorphic widescreen
Anamorphic widescreen, when applied to DVD manufacture, is a video process that horizontally squeezes a widescreen image so that it can be stored in a standard 4:3 aspect ratio DVD image frame. Compatible playback equipment can then re-expand the horizontal dimension to show the original widescreen...
. A number of interactive services including a newer version of Teletext
Teletext
Teletext is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules...
is also offered.
An eight-day Electronic Programme Guide (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
ITV Digital was a British digital terrestrial television broadcaster, which launched a pay-TV service on the world's first digital terrestrial television network as ONdigital in 1998 and briefly re-branded as ITV Digital in July 2001, before the service ceased in May 2002. Its main shareholders...
service, will only display details of 'now and next' programme information.
A fourteen-day Top Up TV
Top Up TV
Top Up TV is a pay television service in the UK launched in March 2004, operating on the digital terrestrial platform. The aim of the service is to "Top Up" Freeview customers by providing additional channels and services....
EPG is an alternative which is available to TUTV-branded PVRs.
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 licence the broadcast of channels in six groups, or multiplexMultiplex (TV)
A multiplex or mux is a group of TV channels that are mixed together for broadcast over a digital TV channel and separated out again by the receiver...
es (abbreviated to 'mux') labelled 1, 2, A, B, C, and D.
The Independent Television Commission
Independent Television Commission
The Independent Television Commission licensed and regulated commercial television services in the United Kingdom between 1 January 1991 and 28 December 2003....
(ITC) allocated each existing analogue terrestrial channel half the capacity of a multiplex each. This meant the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
got a multiplex to themselves (Multiplex 1), ITV
ITV
ITV is the major commercial public service TV network in the United Kingdom. Launched in 1955 under the auspices of the Independent Television Authority to provide competition to the BBC, it is also the oldest commercial network in the UK...
and Channel 4
Channel 4
Channel 4 is a British public-service television broadcaster which began working on 2 November 1982. Although largely commercially self-funded, it is ultimately publicly owned; originally a subsidiary of the Independent Broadcasting Authority , the station is now owned and operated by the Channel...
shared Multiplex 2 (though 3% of the capacity was given to Teletext Ltd.
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 the previous Oracle service which had lost the franchise...
) and Channel 5 and S4C
S4C
S4C , currently branded as S4/C, is a Welsh television channel broadcast from the capital, Cardiff. The first television channel to be aimed specifically at a Welsh-speaking audience, it is the fifth oldest British television channel .The channel - initially broadcast on...
shared Multiplex A. The remaining spectrum (Muliplexes B, C and D) was then auctioned off. A consortium made up of Granada and Carlton
Carlton Communications
Carlton Communications was a British media company. It was led by Michael Green and listed on the London Stock Exchange from 1983 until 2 February 2004, when it taken over by Granada plc to form ITV plc with Carlton gaining 32% of the new company....
(members of the ITV network, which have now merged to form ITV plc
ITV plc
ITV plc is a British media company that operates 12 of the 15 regional television broadcasters that make up the ITV Network, the oldest and largest commercial terrestrial television network in the United Kingdom...
) and BSkyB
British Sky Broadcasting
British Sky Broadcasting Group plc is a satellite broadcasting, broadband and telephony services company headquartered in London, United Kingdom, with operations in the United Kingdom and the Ireland....
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
BBC Choice was a BBC TV station which launched on 23 September 1998 and closed on 9 February 2003. It was the first British TV channel to broadcast exclusively in digital format, and was the first new channel from the BBC since BBC Two launched in 1964...
(which had started on 23 September 1998 with four national variations), BBC News 24
BBC News 24
BBC News is the BBC's 24-hour rolling news television network in the United Kingdom. The channel launched as BBC News 24 on 9 November 1997 at 17:30 as part of the BBC's foray into digital domestic television channels, becoming the first competitor to Sky News, which had been running since 1989...
and BBC Parliament
BBC Parliament
BBC Parliament is a British television channel from the BBC. Its remit is to make accessible to all the work of the parliamentary and legislative bodies of the United Kingdom and the European Parliament...
(albeit in sound only). ITV initially used their space to house ITV2
ITV2
ITV2 is a 24 hour, free-to-air entertainment television channel in the United Kingdom owned by ITV Digital Channels Ltd, a division of ITV plc. It was launched on 7 December 1998, and is available on digital television via satellite, cable, IPTV and terrestrial platforms. The channel has the...
(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
GMTV2
CITV Breakfast is a British digital television station owned by ITV Breakfast Limited, a consortium of ITV plc. It broadcasts every morning between 06:00 and 09:25 . It was designed to complement its sister channel GMTV, and offered children's programming every day...
during the early mornings. Channel 4 used their space for subscription channels FilmFour
Film4
Film4 is a free digital television channel available in the United Kingdom and Republic of Ireland, owned and operated by Channel 4, that screens films.-Programming:...
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 Multiplex A, one of the six groups of channels on digital terrestrial television in the United Kingdom...
(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
BBC Knowledge was an early BBC digital television channel, available by cable, satellite, or terrestrial digital broadcasting, providing a programme of documentary, cultural and educational television.-Launch:...
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
S4C2
S4C2 was a free-to-air British television station owned by S4C which, until 2010, broadcast coverage of the National Assembly for Wales at the Senedd....
outside of 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 DigitalITV 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 as ONdigital in 1998 and briefly re-branded as ITV Digital in July 2001, before the service ceased in May 2002. Its main shareholders...
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 Football League
The Football League, also known as the npower Football League for sponsorship reasons, is a league competition featuring professional association football clubs from England and Wales. Founded in 1888, it is the oldest such competition in world football...
. 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
Churn rate , in its broadest sense, is a measure of the number of individuals or items moving into or out of a collective over a specific period of time...
, an insecure hackable
Pirate decryption
Pirate decryption most often refers to the reception of compromised pay TV or pay radio signals without authorization from the original broadcaster...
encryption
Encryption
In cryptography, encryption is the process of transforming information using an algorithm to make it unreadable to anyone except those possessing special knowledge, usually referred to as a key. The result of the process is encrypted information...
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 BBCBBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
, transmitter company National Grid Wireless (known at the time as Crown Castle UK) and BSkyB. This consortium (legal name DTV Services Ltd and trading under the "Freeview" brand) won and launched a new service. Dropping the ITV Digital failed 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 operates 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
The Championships, Wimbledon
The Championships, Wimbledon, or simply Wimbledon , is the oldest tennis tournament in the world, considered by many to be the most prestigious. It has been held at the All England Club in Wimbledon, London since 1877. It is one of the four Grand Slam tennis tournaments, the other three Majors...
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 TVTop Up TV
Top Up TV is a pay television service in the UK launched in March 2004, operating on the digital terrestrial platform. The aim of the service is to "Top Up" Freeview customers by providing additional channels and services....
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
Turner Classic Movies (UK)
Turner Classic Movies is a subscription digital television channel featuring classic movies, mostly from the Turner Entertainment and Warner Bros. film libraries, which include many MGM, United Artists, RKO and Warner Bros. titles...
purchased its own slot throughout England
England
England is a country that is part of the United Kingdom. It shares land borders with Scotland to the north and Wales to the west; the Irish Sea is to the north west, the Celtic Sea to the south west, with the North Sea to the east and the English Channel to the south separating it from continental...
, Scotland
Scotland
Scotland is a country that is part of the United Kingdom. Occupying the northern third of the island of Great Britain, it shares a border with England to the south and is bounded by the North Sea to the east, the Atlantic Ocean to the north and west, and the North Channel and Irish Sea to the...
and Northern Ireland
Northern Ireland
Northern Ireland is one of the four countries of the United Kingdom. Situated in the north-east of the island of Ireland, it shares a border with the Republic of Ireland to the south and west...
from the multiplex owner, SDN, but rents from Sit-up Ltd
Sit-up Ltd
Bid Shopping is a UK based broadcaster which launched in 2000.To over 12 million homes, it delivers a portfolio of falling price shopping television channels. On 1 April 2009 it was announced that Sit-Up Ltd had been sold by Virgin Media to AURELIUS AG. The purchase price or terms of the agreement...
in Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
, timesharing with bid tv
Bid tv
Bid is a British television shopping channel based in the UK, that runs daily live reversed auctions. It was the first channel of its kind in the world. The channel first launched as Bid-Up.tv. The channel is owned by Bid Shopping.-Bid-Up.TV :...
. 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
Top Up TV
Top Up TV is a pay television service in the UK launched in March 2004, operating on the digital terrestrial platform. The aim of the service is to "Top Up" Freeview customers by providing additional channels and services....
began operating solely on Multiplex A, as Channel 4 reclaimed the bandwidth on Multiplex 2 for its own services More 4, E4, and most recently Film4
Film4
Film4 is a free digital television channel available in the United Kingdom and Republic of Ireland, owned and operated by Channel 4, that screens films.-Programming:...
.
In October 2006, Channel 5 launched two new free-to-air digital channels, Five Life
Five Life
5* is a television channel in the United Kingdom owned by Northern & Shell. The channel was launched as "Five Life" on 15 October 2006, and was rebranded as "Fiver" on 28 April 2008, and "5*" on 7 March 2011. The channel is available on digital television via Freeview, Sky, TalkTalk TV and Virgin...
and Five US
Five US
5USA is an entertainment television channel in the United Kingdom owned by Northern & Shell. It was launched on 16 October 2006 as "Five US" and was the second digital channel in the UK to be launched by RTL Group as part of their multi-channel strategy, the first being Five Life...
, 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 (PVR). At the same time, they started reducing the linear service.
On 19 April 2006, Ofcom ruled that, on request of each multiplex
Multiplex (TV)
A multiplex or mux is a group of TV channels that are mixed together for broadcast over a digital TV channel and separated out again by the receiver...
operator, the 'free-to-air
Free-to-air
Free-to-air describes television and radio services broadcast in clear form, allowing any person with the appropriate receiving equipment to receive the signal and view or listen to the content without requiring a subscription or one-off fee...
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 16QAM 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
UKTV is a digital cable and satellite television network, formed through a joint venture between BBC Worldwide, a commercial subsidiary of the British Broadcasting Corporation, and Scripps Networks Interactive, spun off from The E.W Scripps Company in 2008...
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) codec, which would enable a greater numbner 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 causing failures
During 2008, a rolling programme of transmitter updates caused approximately 250,000 set-top boxes to stop working altogether. 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.Affected models are:
- Digital recorders:
- Bush IDVCR01
- Daewoo DS608P
- Digital boxes:
- Daewoo SV900
- Labgear DTT100
- Portland DP100
- Triax DVB2000T
Some other models and televisions also require an over-air download for correct operation.
Digital switchover
- For full list of dates, see Digital switchover dates in the United Kingdom.
Summary
The UK Government's intention is that digital terrestrial televisionDigital terrestrial television
Digital terrestrial television is the technological evolution of broadcast television and advance from analog television, which broadcasts land-based signals...
will completely replace analogue terrestrial television in the United Kingdom
Analogue terrestrial television in the United Kingdom
Analogue terrestrial television in the United Kingdom is, traditionally, the method most people in the UK, Channel Islands and the Isle of Man used to receive television...
, the Isle of Man
Isle of Man
The Isle of Man , otherwise known simply as Mann , is a self-governing British Crown Dependency, located in the Irish Sea between the islands of Great Britain and Ireland, within the British Isles. The head of state is Queen Elizabeth II, who holds the title of Lord of Mann. The Lord of Mann is...
by 2012, and the Channel Islands
Channel Islands
The Channel Islands are an archipelago of British Crown Dependencies in the English Channel, off the French coast of Normandy. They include two separate bailiwicks: the Bailiwick of Guernsey and the Bailiwick of Jersey...
by 2010. This process is known as "Digital Switchover", or DSO. The Digital TV Group
Digital TV Group
The Digital TV Group is the industry association for Digital Television in the United Kingdom : The Group was formed in 1995 to set technical standards for the implementation of digital terrestrial television in the UK and now encompasses all digital TV platforms and convergence issues...
the industry association for digital television in the UK, is responsible for co-ordination between Freeview and other digital services. DTG licences suitable equipment to bear the Digital Tick and Freeview Playback Logos to identify PVRs and digital TV services 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
DVB-T is an abbreviation for Digital Video Broadcasting — Terrestrial; it 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 the UK in 1998...
international standard.
The Digital Switchover process is already underway in parts of the UK, and it involves discontinuing analogue terrestrial TV broadcasts. In some areas this will allow greater signal strength and/or better coverage of digital multiplexes.
In areas where analogue signals have been terminated, older receiving equipment is likely to require replacement or upgrade. This process is being subsidised by the UK Government for those on low incomes. Current contracts for this operation have been awarded to BSkyB in the Borders region. Upgrading of analogue receiving equipment requires a Freeview set-top box (or other digital receiver). Where an analogue TV recording device is in use ideally this will be provided with a separate Freeview set-top box, to replicate existing functionality of recording and watching different programme sources.
History
The progress towards digital switchover in the UK has been long. The then-Secretary of State for Culture, Media and SportSecretary of State for Culture, Media and Sport
The Secretary of State for Culture, Olympics, Media and Sport is a United Kingdom cabinet position with responsibility for the Department for Culture, Media and Sport. The role was created in 1992 by John Major as Secretary of State for National Heritage...
, Chris Smith
Chris Smith, Baron Smith of Finsbury
Christopher "Chris" Robert Smith, Baron Smith of Finsbury PC is a British Labour Party politician, and a former Member of Parliament and Cabinet Minister...
, 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
International Telecommunication Union
The International Telecommunication Union is the specialized agency of the United Nations which is responsible for information and communication technologies...
to call a Regional Radiocommunication Conference to establish a frequency plan 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 & June 2006.
On 15 September 2005, addressing the Royal Television Society
Royal Television Society
The Royal Television Society 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...
in Cambridge
Cambridge
The city of Cambridge is a university town and the administrative centre of the county of Cambridgeshire, England. It lies in East Anglia about north of London. Cambridge is at the heart of the high-technology centre known as Silicon Fen – a play on Silicon Valley and the fens surrounding the...
, Smith's successor at the DCMS
Department for Culture, Media and Sport
The Department for Culture, Media and Sport is a department of the United Kingdom government, with responsibility for culture and sport in England, and some aspects of the media throughout the whole UK, such as broadcasting and internet....
, Tessa Jowell
Tessa Jowell
Tessa Jowell is a British Labour Party politician, who has been the Member of Parliament for Dulwich and West Norwood since 1992. Formerly a member of both the Blair and Brown Cabinets, she is currently the Shadow Minister for the Olympics and Shadow Minister for London.-Early life:Tessa Jane...
, announced the go-ahead for switchover in the UK, coupled with support measures to ensure the disadvantaged are not left behind.
In essence, the UK will switchover on a regional basis, starting in Whitehaven
Whitehaven
Whitehaven is a small town and port on the coast of Cumbria, England, which lies equidistant between the county's two largest settlements, Carlisle and Barrow-in-Furness, and is served by the Cumbrian Coast Line and the A595 road...
on the 17 October 2007, then the rest of the Border Television
Border Television
Border Television is the ITV franchise holder for the Border region, spanning the England/Scotland border and covering Dumfries & Galloway region, a small part of the south-west area of Ayrshire, the Scottish Borders, parts of north and west Northumberland and the majority of Cumbria...
region in the second half of 2008, and then finishing in London in 2012. Local television broadcasters, including the BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
and ITV
ITV
ITV is the major commercial public service TV network in the United Kingdom. Launched in 1955 under the auspices of the Independent Television Authority to provide competition to the BBC, it is also the oldest commercial network in the UK...
, are actively encouraging viewers to upgrade to digital television. UK broadcasters are also under additional pressure to complete migration since London will be hosting the Olympic Games in 2012.
On the day after Jowell's speech, an independent. not-for-profit company, Digital UK
Digital UK
Digital UK is the body in charge of the digital switchover of television in the United Kingdom.Digital UK communicates switchover to the public, works with industry to build support for the switchover programme, and co-ordinates engineering work across the UK broadcast network...
, was established to coordinate the switchover process. Set up by the broadcasters and the commercial multiplex operators, Digital UK is required to co-ordinate the project and ensure that the public are kept informed about progress.
Digital rollout
The British Government has given OfcomOfcom
Ofcom is the government-approved regulatory authority for the broadcasting and telecommunications industries in the United Kingdom. Ofcom was initially established by the Office of Communications Act 2002. It received its full authority from the Communications Act 2003...
and Digital UK
Digital UK
Digital UK is the body in charge of the digital switchover of television in the United Kingdom.Digital UK communicates switchover to the public, works with industry to build support for the switchover programme, and co-ordinates engineering work across the UK broadcast network...
jointly the task of discontinuing analogue television broadcasting. The switch-off will occur on an ITV sub-region basis. A technical trial in Ferryside, Wales, resulted in viewers voting to lose three out of the four available analogue channels in favour of going digital, so the unwanted analogue signals were switched off at the end of March 2005. 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 with the ITV Border
Border Television
Border Television is the ITV franchise holder for the Border region, spanning the England/Scotland border and covering Dumfries & Galloway region, a small part of the south-west area of Ayrshire, the Scottish Borders, parts of north and west Northumberland and the majority of Cumbria...
Selkirk region, then Caldbeck (which is being rebuilt, and will broadcast both England and Scotland multiplexes to improve service to viewers north of the border; the nearby Sandale transmitter will cease to broadcast TV), ITV Westcountry
Westcountry Television
Westcountry Television, is the ITV franchise holder in the South West of England, replacing its predecessor, TSW , from the 1 January 1993...
Beacon Hill, Stockland Hill, Huntshaw Cross, Redruth, Caradon Hill, Wales
Wales
Wales is a country that is part of the United Kingdom and the island of Great Britain, bordered by England to its east and the Atlantic Ocean and Irish Sea to its west. It has a population of three million, and a total area of 20,779 km²...
Preseli, Carmel, ITV Granada
Granada Television
Granada Television is the ITV contractor for North West England. Based in Manchester since its inception, it is the only surviving original ITA franchisee from 1954 and is ITV's most successful....
whole region, Wales Llanddona, Moel-Y-Parc, Blaenplwyf, Long Mountain, Wenvoe then the rest of the UK: ITV West, STV North
Grampian Television
Grampian Television is the ITV franchisee for the North and North East of Scotland. Its coverage area includes the Scottish Highlands , Inverness, Aberdeen, Dundee and parts of north Fife...
and Channel Television
Channel Television
Channel Television is a British television station which has served as an Independent Television contractor to the Channel Islands since 1962. It is based in Jersey...
in 2010; STV Central
Scottish Television
Scottish Television is Scotland's largest ITV franchisee, and has held the ITV franchise for Central Scotland since 31 August 1957. It is the second oldest ITV franchisee still active...
from 2010–11; ITV Central
Central Independent Television
Central Independent Television, more commonly known as Central is the Independent Television contractor for the Midlands, created following the restructuring of ATV and commencing broadcast on 1 January 1982. The station is owned and operated by ITV plc, under the licensee of ITV Broadcasting...
, ITV Yorkshire
Yorkshire Television
Yorkshire Television, now officially known as ITV Yorkshire and sometimes unofficially abbreviated to YTV, is a British television broadcaster and the contractor for the Yorkshire franchise area on the ITV network...
and ITV Anglia
Anglia Television
Anglia Television is the ITV franchise holder for the East Anglia franchise region. Although Anglia Television takes its name from East Anglia, its transmission coverage extends beyond the generally accepted boundaries of that region. The station is based at Anglia House in Norwich, with regional...
in 2011; and finally ITV Meridian
Meridian Broadcasting
Meridian Broadcasting is the holder of the ITV franchise for the South and South East of England. The station is owned and operated by ITV plc, under the licensee of ITV Broadcasting Limited....
, ITV London
ITV London
ITV London is the on-air brand name used by ITV Broadcasting Limited for the two Channel 3 broadcast franchises, Carlton Television and London Weekend Television in the London ITV region.-History:...
, ITV Tyne Tees
Tyne Tees Television
Tyne Tees Television is the ITV television franchise for North East England and parts of North Yorkshire. As of 2009, it forms part of a non-franchise ITV Tyne Tees & Border region, shared with the ITV Border region...
& UTV
UTV
UTV is a television channel based in the UK region of Northern Ireland. The channel is the Channel 3 or Independent Television licensee for Northern Ireland and is operated by UTV Limited, a wholly owned subsidiary of UTV Media.- Terrestrial :* Analogue: Normally tuned to 3 * Freeview : 3...
in 2012.
Many decisions must 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 presently have, and who may be reluctant to buy a digital box in order to view the free channels. The government has 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 will not lose their television services when analogue transmissions are switched off.
Another issue is that the "98.5 per cent of the population" availability target can 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 will allocate frequencies for groups of households to provide "self-help" relay transmitters at their own expense (for analogue broadcasts there are some 200 of these, serving around 13,000 households), but suggests that in such cases, terrestrial TV may no longer be the most cost-effective solution.
Landlords of communal housing are likely to have to upgrade old master aerial TV distribution systems. A new alternative, the integrated reception system
Integrated reception system
An integrated reception system provides broadcast signals from multiple sources to multiple outlets, via a single aerial cluster and signal booster-distributor...
is being promoted as a way to offer the full range of terrestrial and satellite broadcasts from a single aerial cluster; however, residents are likely to be asked to pay substantially higher annual charges when such a system is installed.
The switchover process
After several months of press publicity, leaflet drops, public meetings etc., captions will start appearing on analogue broadcasts from the affected transmitters, warning viewers that the analogue service will shortly be switched off and that they 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 will be distributed. Although viewers who live outside existing Freeview reception areas will be unable to test any digital receiving equipment they buy at this early stage, test-screens on CeefaxCeefax
Ceefax is the BBC's teletext information service transmitted via the analogue signal, started in 1974 and will run until April 2012 for Pages from Ceefax, while the actual interactive service will run until 24 October 2012, in-line with the digital switchover.-History:During the late 60s, engineer...
(BBC One & Two) and Teletext
Teletext
Teletext is a television information retrieval service developed in the United Kingdom in the early 1970s. It offers a range of text-based information, typically including national, international and sporting news, weather and TV schedules...
(ITV & C4/S4C) page 284 make it possible to determine whether they are likely to need a new aerial or a signal amplifier to receive digital transmissions.
Next, detailed information booklets will be delivered to all households in the area (including many on the fringe who may be receiving their TV from other transmitters- hence the importance of the on-screen warning captions). Two or three months later, the analogue BBC Two
BBC Two
BBC Two is the second television channel operated by the British Broadcasting Corporation in the United Kingdom. It covers a wide range of subject matter, but tending towards more 'highbrow' programmes than the more mainstream and popular BBC One. Like the BBC's other domestic TV and radio...
signal will be replaced with Multiplex 1. At the same time, captions will appear on the remaining analogue channels reminding viewers of the impending switchover. Finally, four weeks later, the remaining analogue transmissions will be switched off, with the analogue ITV signal being replaced with Multiplex 2, and the analogue BBC One
BBC One
BBC One is the flagship television channel of the British Broadcasting Corporation in the United Kingdom. It was launched on 2 November 1936 as the BBC Television Service, and was the world's first regular television service with a high level of image resolution...
signal with Multiplex B. At some locations, during the four-week switchover period, BBC One, ITV or Channel 4 will move to the analogue BBC Two frequency where that channel's frequency is required for the digital transmission of Multiplex 1.
Three multiplexes (current multiplexes 1, 2 and B) will be for public service broadcasting
Public service broadcasting in the United Kingdom
In the United Kingdom the term "public service broadcasting" refers to broadcasting intended for the public benefit rather than for purely commercial concerns. The communications regulator Ofcom, requires that certain television and radio broadcasters fulfil certain requirements as part of their...
and contain around 25 TV channels, including all the television channels from the BBC, ITV (except ITV2+1), Channel 4 (except Film4 and E4+1), S4C and Channel 5 (except 5 USA and 5*), half a dozen radio stations and half a dozen text/interactive services. The other three multiplexes (A, C and D) will continue to be operated by their respective commercial licence-holders. To reflect the slightly changed roles, the multiplex names will change:
| Old multiplex name | New multiplex name | Owning company |
|---|---|---|
| 1 | BBC A | BBC BBC The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff... |
| 2 | D3&4 | Digital 3&4 Digital 3&4 Digital 3&4 is a consortium consisting of regional Channel 3 companies and Channel 4 Television Corporation, which operates a multiplex broadcasting from a number of transmitter sites in the UK, carrying television and radio channels from both ITV and Channel 4; however three per-cent of the... |
| A | SDN | S4C Digital Networks S4C Digital Networks SDN is a company that operates Multiplex A, one of the six groups of channels on digital terrestrial television in the United Kingdom... (ITV plc ITV plc ITV plc is a British media company that operates 12 of the 15 regional television broadcasters that make up the ITV Network, the oldest and largest commercial terrestrial television network in the United Kingdom... ) |
| B | BBC B | BBC BBC The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff... |
| C | Arqiva A | Arqiva Arqiva Arqiva is a telecommunications company which provides infrastructure and broadcast transmission facilities in the United Kingdom and Republic of Ireland. The present company, with headquarters located at Crawley Court in the village of Crawley, Hampshire, was formed by National Grid Wireless... |
| D | Arqiva B | Arqiva Arqiva Arqiva is a telecommunications company which provides infrastructure and broadcast transmission facilities in the United Kingdom and Republic of Ireland. The present company, with headquarters located at Crawley Court in the village of Crawley, Hampshire, was formed by National Grid Wireless... |
Post-switchover
The adoption of the technically superior DVB-T 8k format occurs in each region at the date of switchover. This results 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 will form a Single Frequency Network when they are converted to all digital operation.
Alternative post-switchover multiplex designations have been used on internal documentation by the BBC switchover contractor Arqiva, however 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 is complete, two new sub-bands of the UHF
Ultra high frequency
Ultra-High Frequency designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz , also known as the decimetre band or decimetre wave as the wavelengths range from one to ten decimetres...
spectrum will be clear (frequencies corresponding to channel ranges 31-40 and 62 to 69), leaving only channels 21-30 and 41-62 for digital television multiplexes. This "digital dividend" will require 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
Range
-In mathematics:* Range , the set of all output values produced by a function* Interval , also called a range, a set of real numbers that includes all numbers between any two numbers in the set...
. Following a consultation, in September 2011 Ofcom stated that an auction for 600 MHz spectrum 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 servicesDVB-HDVB-H is one of three prevalent mobile TV formats. It is a technical specification for bringing broadcast services to mobile handsets. DVB-H was formally adopted as ETSI standard EN 302 304 in November 2004. The DVB-H specification can be downloaded from the official DVB-H website...
- Wireless (mobile) broadbandMobile BroadbandMobile broadband is the marketing term for wireless Internet access through a portable modem, mobile phone or other mobile device.-Description:...
services - Wider coverage for advanced services in remote and rural areas
- More multiplexes carrying more channels
- High definitionHigh-definition televisionHigh-definition television is video that has resolution substantially higher than that of traditional television systems . HDTV has one or two million pixels per frame, roughly five times that of SD...
services
The clearing and re-allocation of these channels of the spectrum for other services has caused some controversy within technical industries, as Telecoms govorning body OfCom decided to clear Channel 69 (854-862MHz) in order to match the rest of Europe and make the facilitation of future services easier.. (For more information see Wireless Microphones
Wireless microphone
A wireless microphone, as the name implies, is a microphone without a physical cable connecting it directly to the sound recording or amplifying equipment with which it is associated...
)
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 an announcement on their website.
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 LucasMatt Lucas
Matthew Richard "Matt" Lucas is an English comedian, screenwriter and actor best known for his acclaimed work with David Walliams in the television show Little Britain; as well as for his portrayals of the scorekeeping baby George Dawes in the comedy panel game Shooting Stars, Tweedledee and...
, used in material publicising the digital switchover. He will appear in the public information programme run by Digital UK
Digital UK
Digital UK is the body in charge of the digital switchover of television in the United Kingdom.Digital UK communicates switchover to the public, works with industry to build support for the switchover programme, and co-ordinates engineering work across the UK broadcast network...
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 OFCOM 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.Future of digital terrestrial broadcasting
In March 2006, the development of a new second generation digital terrestrial broadcasting standard, DVB-T2DVB-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 television....
, was agreed by the DVB Group. It is expected that it will be finalised during 2008, ready for deployment in 2009.
The BBC
BBC
The British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
, ITV
ITV
ITV is the major commercial public service TV network in the United Kingdom. Launched in 1955 under the auspices of the Independent Television Authority to provide competition to the BBC, it is also the oldest commercial network in the UK...
, Channel 4
Channel 4
Channel 4 is a British public-service television broadcaster which began working on 2 November 1982. Although largely commercially self-funded, it is ultimately publicly owned; originally a subsidiary of the Independent Broadcasting Authority , the station is now owned and operated by the Channel...
S4C
S4C
S4C , currently branded as S4/C, is a Welsh television channel broadcast from the capital, Cardiff. The first television channel to be aimed specifically at a Welsh-speaking audience, it is the fifth oldest British television channel .The channel - initially broadcast on...
and Channel 5 agreed with the regulator Ofcom
Ofcom
Ofcom is the government-approved regulatory authority for the broadcasting and telecommunications industries in the United Kingdom. Ofcom was initially established by the Office of Communications Act 2002. It received its full authority from the Communications Act 2003...
to convert one UK multiplex (B, or PSB3) to DVB-T2 to increase capacity for HDTV (High Definition Television) via DTT. They expect the first TV region to use the new standard will be Granada
Granada Television
Granada Television is the ITV contractor for North West England. Based in Manchester since its inception, it is the only surviving original ITA franchisee from 1954 and is ITV's most successful....
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.
From 27 October 2009, Multiplex B (PSB 3) was cleared of SD channels in post DSO areas. Multiplex B in pre DSO areas will carry BBC Four, BBC Parliament, CBeebies, BBC Radio Stations, 301 until DSO where they will move to Multiplex 1 (PSB1). Former streams of 302 and News Multiscreen on Multiplex B are to sublet to other broadcasters than the BBC for pre DSO areas only, and not available at all in post DSO because of the new DVB-T2 HD multiplex as replacement. At this time, Community Channel is the only broadcaster using these streams.
Ofcom recently published its final decision for HDTV using DVB-T2 and MPEG-4: BBC HD
BBC HD
BBC HD is a high-definition television network 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...
, ITV1 HD, Channel 4 HD
Channel 4
Channel 4 is a British public-service television broadcaster which began working on 2 November 1982. Although largely commercially self-funded, it is ultimately publicly owned; originally a subsidiary of the Independent Broadcasting Authority , the station is now owned and operated by the Channel...
/S4C Clirlun
S4C
S4C , currently branded as S4/C, is a Welsh television channel broadcast from the capital, Cardiff. The first television channel to be aimed specifically at a Welsh-speaking audience, it is the fifth oldest British television channel .The channel - initially broadcast on...
will each have one slot from launch. 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 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
BBC One
BBC One is the flagship television channel of the British Broadcasting Corporation in the United Kingdom. It was launched on 2 November 1936 as the BBC Television Service, and was the world's first regular television service with a high level of image resolution...
launched on Freeview HD. It is available in addition to the existing BBC HD channel. During 2011, Ofcom
Ofcom
Ofcom is the government-approved regulatory authority for the broadcasting and telecommunications industries in the United Kingdom. Ofcom was initially established by the Office of Communications Act 2002. It received its full authority from the Communications Act 2003...
intends to give the Commercial Public Service Broadcasters another opportunity to apply to provide an additional HD service from 2012.
List of digital terrestrial channels
The multiplexes
- Multiplex 1
- Operated by the BBCBBCThe British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
; broadcasts nationwide in 16QAM mode at 18 megabits/second in pre-switchover areas, 64QAM mode at 24 megabits/second in post-switchover regions.
- Multiplex 2
- Operated by Digital 3&4Digital 3&4Digital 3&4 is a consortium consisting of regional Channel 3 companies and Channel 4 Television Corporation, which operates a multiplex broadcasting from a number of transmitter sites in the UK, carrying television and radio channels from both ITV and Channel 4; however three per-cent of the...
(an ITV/Channel 4 consortium); broadcasts nationwide in 64QAM mode at 24 megabits/second
- Multiplex A
- Operated by SDNS4C Digital NetworksSDN is a company that operates Multiplex A, one of the six groups of channels on digital terrestrial television in the United Kingdom...
(owned by ITV plc); broadcasts nationwide in 64QAM mode at 24 megabits/second
- Multiplex B
- Operated by the BBCBBCThe British Broadcasting Corporation is a British public service broadcaster. Its headquarters is at Broadcasting House in the City of Westminster, London. It is the largest broadcaster in the world, with about 23,000 staff...
; currently broadcasts nationwide in 16QAM mode at 18 megabits/second. Multiplex B is being cleared and is to be used for the forthcoming High Definition broadcasts, at which point it will switch to DVB-T2 format broadcasts with an effective multiplex capacity of 36 megabits/second. The dates for this changeover vary by region.
- Multiplex C
- Operated by ArqivaArqivaArqiva is a telecommunications company which provides infrastructure and broadcast transmission facilities in the United Kingdom and Republic of Ireland. The present company, with headquarters located at Crawley Court in the village of Crawley, Hampshire, was formed by National Grid Wireless...
; broadcasts nationwide in 16QAM mode at 18 megabits/second
- Multiplex D
- Operated by ArqivaArqivaArqiva is a telecommunications company which provides infrastructure and broadcast transmission facilities in the United Kingdom and Republic of Ireland. The present company, with headquarters located at Crawley Court in the village of Crawley, Hampshire, was formed by National Grid Wireless...
; broadcasts nationwide in 16QAM mode at 18 megabits/second
Use of multiplexing technology
Each multiplex is an error-protected bitstreamBitstream
A bitstream or bit stream is a time series of bits.A bytestream is a series of bytes, typically of 8 bits each, and can be regarded as a special case of a bitstream....
of 18 or 24 megabits per second, which can be used for almost any combination of digitally-encoded video, audio
Sound
Sound is a mechanical wave that is an oscillation of pressure transmitted through a solid, liquid, or gas, composed of frequencies within the range of hearing and of a level sufficiently strong to be heard, or the sensation stimulated in organs of hearing by such vibrations.-Propagation of...
and data
Data
The term data refers to qualitative or quantitative attributes of a variable or set of variables. Data are typically the results of measurements and can be the basis of graphs, images, or observations of a set of variables. Data are often viewed as the lowest level of abstraction from which...
. 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 at different times. For example CBeebiesCBeebiesCBeebies is the brand used by the BBC for programming aimed at children 6 years and under. It is used as a themed strand in the UK on terrestrial television, as a separate free-to-air domestic British channel and used for international varients supported by advertising, subscription or both...
and BBC FourBBC FourBBC Four is a British television network operated by the British Broadcasting Corporation and available to digital television viewers on Freeview, IPTV, satellite and cable....
currently use the same space in Multiplex B, with CBeebies broadcasting from 6am until 7pm and BBC Four from 7pm; similarly for CBBCCBBCCBBC is one of two brand names used for the BBC's children's television strands. Between 1985 and 2002, CBBC was the name given to all the BBC's programmes on TV for children aged under 14...
and BBC ThreeBBC ThreeBBC Three is a television network from the BBC broadcasting via digital cable, terrestrial, IPTV and satellite platforms. The channel's target audience includes those in the 16-34 year old age group, and has the purpose of providing "innovative" content to younger audiences, focusing on new talent...
.
- some multiplexes allocate more bandwidth to services, providing a smaller number of higher-quality services. For example BBC OneBBC OneBBC One is the flagship television channel of the British Broadcasting Corporation in the United Kingdom. It was launched on 2 November 1936 as the BBC Television Service, and was the world's first regular television service with a high level of image resolution...
on Multiplex 1 is carried as a 4.4 MegabitMegabitThe megabit is a multiple of the unit bit for digital information or computer storage. The prefix mega is defined in the International System of Units as a multiplier of 106 , and therefore...
stream, while QVCQVCQVC is a multinational corporation specializing in televised home shopping. Founded in 1986 by Joseph Segel in West Goshen Township, Pennsylvania, United States, QVC broadcasts in five countries as QVC US, QVC UK, QVC Germany, QVC Japan and – QVC Italy to 200 million households...
on Multiplex A typically uses 2 MegabitMegabitThe megabit is a multiple of the unit bit for digital information or computer storage. The prefix mega is defined in the International System of Units as a multiplier of 106 , and therefore...
s per second.
- The modulationModulationIn electronics and telecommunications, modulation is the process of varying one or more properties of a high-frequency periodic waveform, called the carrier signal, with a modulating signal which typically contains information to be transmitted...
of the multiplexes can be varied to squeeze higher digitalDigitalA digital system is a data technology that uses discrete values. By contrast, non-digital systems use a continuous range of values to represent information...
bitrateBitrateIn telecommunications and computing, bit rate is the number of bits that are conveyed or processed per unit of time....
s out of the same portion of the electromagnetic spectrumElectromagnetic spectrumThe electromagnetic spectrum is the range of all possible frequencies of electromagnetic radiation. The "electromagnetic spectrum" of an object is the characteristic distribution of electromagnetic radiation emitted or absorbed by that particular object....
, 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 (only used for tests in the Oxford and London areas)
- 16 QAMQuadrature amplitude modulationQuadrature amplitude modulation is both an analog and a digital modulation scheme. It conveys two analog message signals, or two digital bit streams, by changing the amplitudes of two carrier waves, using the amplitude-shift keying digital modulation scheme or amplitude modulation analog...
- 64 QAMQuadrature amplitude modulationQuadrature amplitude modulation is both an analog and a digital modulation scheme. It conveys two analog message signals, or two digital bit streams, by changing the amplitudes of two carrier waves, using the amplitude-shift keying digital modulation scheme or amplitude modulation analog...
- As of late 2009 multiplexes 2 and A use 64 QAM and are consequently more prone to poor reception, while the other multiplexes use 16 QAM. At switchover the transmission mode will change from 16QAM to 64QAM on Multiplex 1 (PSB1), increasing the effective bandwidth of the multiplex. The switch to 64QAM mode would provide extra bandwidth on Multiplexes C (COM5) and D (COM6).
- Multiplexes can make use of statistical multiplexingStatistical multiplexingStatistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation . In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bit-rate digital channels or data streams. The link sharing is adapted to the...
at the MPEG 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. The only DTT channel which in most regions does not use statistical multiplexing at present, i.e. which uses a constant bit rate, is BBC One. This is so the English Regions and Nations can perform a simple transmultiplex, or T-Mux, operation and insert their local versions of BBC One over the London feed straight into the existing BBC Multiplex 1 without having to re-encode the entire multiplex at each regional centre, requiring specialist (and costly) equipment at several locations. However, a different approach is taken in each region once full 'digital switchover' occurs, at which point the BBC assembles and broadcasts a fully statistically multiplexed 64QAM multiplex for each region.
New compression technology
Developments in statistical multiplexingStatistical multiplexing
Statistical multiplexing is a type of communication link sharing, very similar to dynamic bandwidth allocation . In statistical multiplexing, a communication channel is divided into an arbitrary number of variable bit-rate digital channels or data streams. The link sharing is adapted to the...
, improved compression technology, and, in some cases, an acceptance of lower quality or lower resolution broadcasts, has allowed gradual increases in the number of services carried on digital terrestrial television multiplexes.
As the number of homes receiving digital terrestrial grows, the interest in new channel capacity has similarly 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
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 and satellite broadcaster British Sky Broadcasting in 1996...
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
More4 is a digital television channel, run by British broadcaster Channel 4, that launched on 10 October 2005. It is carried on Freeview, on satellite broadcasters Freesat and Sky, UK IPTV broadcaster TalkTalk TV and on UK cable network Virgin Media and in the Republic of Ireland cable networks...
) 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
Channel 4 is a British public-service television broadcaster which began working on 2 November 1982. Although largely commercially self-funded, it is ultimately publicly owned; originally a subsidiary of the Independent Broadcasting Authority , the station is now owned and operated by the Channel...
; it was occupied by More4+1
More4
More4 is a digital television channel, run by British broadcaster Channel 4, that launched on 10 October 2005. It is carried on Freeview, on satellite broadcasters Freesat and Sky, UK IPTV broadcaster TalkTalk TV and on UK cable network Virgin Media and in the Republic of Ireland cable networks...
until live coverage of Big Brother replaced it on 18 May 2006. Film4
Film4
Film4 is a free digital television channel available in the United Kingdom and Republic of Ireland, owned and operated by Channel 4, that screens films.-Programming:...
took over the slot 23 July 2006.
More recent compression technology, as now available in codec
Codec
A codec is a device or computer program capable of encoding or decoding a digital data stream or signal. The word codec is a portmanteau of "compressor-decompressor" or, more commonly, "coder-decoder"...
s like MPEG4, H.264 or Microsoft's WMV could enable a substantial increase in either quality or capacity due to their increased efficiency. 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, who are now broadcasting high-definition television
High-definition television
High-definition television is video that has resolution substantially higher than that of traditional television systems . HDTV has one or two million pixels per frame, roughly five times that of SD...
on Freeview in the new DVB-T2 format, 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 polarised, 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. However, this would have required new transmitters and aerials, as well as new receiving equipment, and the technique was ultimately not adopted.
See also
- Digital television in the United KingdomDigital television in the United KingdomThe United Kingdom now has three major forms of broadcast digital television , a direct-to-home satellite service from the Astra 28.2°E satellites provided by British Sky Broadcasting and Freesat, digital cable television services provided by Virgin Media and WightCable, and a free-to-air digital...
- Top Up TVTop Up TVTop Up TV is a pay television service in the UK launched in March 2004, operating on the digital terrestrial platform. The aim of the service is to "Top Up" Freeview customers by providing additional channels and services....
- BT VisionBT VisionBT Vision is a hybrid IPTV-digital terrestrial television service provided by BT Group in the United Kingdom which was launched in December 2006...
- FreesatFreesatFreesat is a free-to-air digital satellite television joint venture between the BBC and ITV plc, serving the United Kingdom. The service was formed as a memorandum in 2007 and has been marketed since 6 May 2008...
- High-definition television in the United KingdomHigh-definition television in the United KingdomHigh-definition television in the United Kingdom is available via cable, IPTV, satellite and terrestrial television. The first high-definition broadcasts began in 2006 and the number of channels has grown to 65 ....
- List of British television channels
Official sites
- Digital Switchover UK
- BBC – Digital – Homepage
- BBC – Digital – Switchover
- Freeview official site
- Top Up TV
- DigitalUK
- Ofcom's list of the current licensed digital television services
- Digital TV Consumer test reports UK Government-funded website to support Digital Switchover