Research and analysis

Stakeholder Forum Papers: Annex B - Technology explainer in future of TV distribution

Published 23 June 2026

B1. Purpose of this annex

This annex explains, in everyday language, the main technologies and technical terms used in this paper. It is written for readers who are not broadcast or telecoms specialists.

Where there is any doubt, the DTG D-Book – the definitive technical specification for UK digital TV – and associated standards remain the authoritative technical reference.

B2. How TV reaches homes today

B2.1 Two main ways to watch TV

1. Broadcast TV (over the air or by satellite)
* In the UK the main free broadcast platforms are Freeview (via an aerial – digital terrestrial television, DTT) and Freesat (via a satellite dish).
* Freeview TV signals are sent from large masts (transmitters) across the country, and
rooftop or indoor aerial receives the signal, and your TV or set-top box turns it into pictures and sound.
* Freesat TV signals are sent from a satellite which are received by a dish, and your TV or set-top box turns the signal into pictures and sound

2. TV over the internet (IP / streaming)
* Programmes travel through broadband networks (usually via a telephone cable or fIbre-optic cable into your home) instead of the airwaves.
* You watch using a smart TV, set-top box, streaming stick, games console, phone or tablet.
* Examples include BBC iPlayer, ITVX and other video-on-demand and subscription services.

Most UK homes now use both broadcast and internet services – often on the same device. This paper describes that as a hybrid environment.

B2.2 Freeview and digital terrestrial television (DTT)

• Freeview is the UK’s main free-to-air TV platform that uses an aerial.
• Technically, it is digital terrestrial television (DTT) – “digital” because the signal is digital, “terrestrial” because it comes from masts on land.
• Freeview carries over 100 TV and radio services in a mix of standard definition (SD) and high definition (HD).

B2.3 What is a multiplex?

A multiplex (often shortened to mux) is a digital “bundle” of TV and radio services transmitted together on one radio frequency.

• Think of one multiplex as a lorry on a motorway.
• The lorry (the multiplex) carries many boxes (channels) along the same road (frequency).

The UK has:

• PSB multiplexes – carrying public service broadcaster channels (BBC, ITV, Channel 4 and Channel 5).
• Commercial multiplexes (COM muxes) – carrying mainly commercial channels.
• A Local TV multiplex – carrying local channels and some extra national services.
• A Northern Ireland multiplex (NI Mux) – carrying Irish channels in Northern Ireland.

B3. Key broadcast technologies in this paper

B3.1 DVB-T and DVB-T2 – how the digital signal is packed

DVB stands for Digital Video Broadcasting, a family of standards used for digital TV in Europe and many other regions.

• DVB-T
  • First-generation standard for digital terrestrial TV.
  • Used for the original UK Freeview service after analogue switch-off.
  • Less efficient – it fits fewer channels into the available spectrum.
• DVB-T2
  • Newer, second-generation standard.
  • More efficient – it can carry more channels or higher-quality pictures in the same spectrum.
  • Enables more HD services and lower energy use for the same amount of viewing.

This paper models a future DTT platform where all national multiplexes use DVB-T2. When it refers to “T2 sets” it means TVs and boxes that can receive DVB-T2. Older DVB-T-only equipment would need an adaptor or replacement to continue to receive services after any full T2 switchover.

B3.2 Codecs – how video and audio are compressed

Video and audio take up a lot of data. To make broadcasting practical, signals are compressed before transmission and decompressed in the TV or set-top box. The compressor–decompressor is called a codec.

The main video codecs in this paper are:

• MPEG-2 – older compression format used for many early digital TV services, mainly SD. It needs more capacity for the same quality than newer codecs.
• MPEG-4 AVC (H.264) – widely used today and more efficient than MPEG-2. The proposed future DTT platform uses DVB-T2 with MPEG-4 AVC as its baseline.
• HEVC (H.265) – a newer codec that can give roughly 40–50% more compression than MPEG-4 AVC for similar picture quality. Already used in many streaming services and newer TVs, in particular for higher resolution video, ultra high definition (UHD). The paper suggests planning for HEVC-capable receivers so that future upgrades are possible without extra spectrum.

In simple terms: newer codecs fit more or better-quality TV into the same “pipe”.

B3.3 SD, HD and larger screens

• SD (standard definition) – older, lower-resolution TV picture. Acceptable on small screens but often looks soft on modern 40–65-inch TVs.
• HD (high definition) – sharper picture with more detail and better colour, suited to today’s larger screens.
• UHD / 4K (ultra-high definition) – very high-resolution picture, usually delivered via the internet or satellite today.

As screens get larger, SD pictures appear worse, so the paper notes a general industry move towards HD-first services and, over time, away from SD on DTT.

B3.4 Spectrum, UHF bands and 600 MHz clearance

Radio spectrum is the range of radio frequencies used for TV, radio, mobile and other wireless services. It is finite and managed by government and regulators.

Digital terrestrial TV uses part of the UHF (ultra high frequency) band, currently 470–694 MHz in the UK. Bands immediately above this have already been reallocated to mobile broadband.

• The paper explores clearing the 600 MHz band (roughly 614–694 MHz) by 2034.
• Clearing means moving TV multiplexes to different frequencies so that the cleared band can be auctioned or used for other services such as 5G/6G mobile.

For viewers, spectrum clearance mainly means:

• retuning TVs and boxes;
• in a minority of cases, fitting filters to aerial systems if new mobile signals interfere with TV reception;
• a managed engineering programme at transmitter sites.

B3.5 Transmitters, relays and coverage

• Main transmitters are large broadcast masts serving wide areas.
• Relays are smaller transmitters that fill coverage gaps, for example in valleys or remote areas.

PSB multiplexes use both main transmitters and relays and reach about 98.5% of homes. Commercial multiplexes usually use only main sites and reach around 90% of homes. Maintaining this level of coverage is part of the UK’s universality objective.

B3.6 Hybrid TV and IP delivery

IP (Internet Protocol) is the standard way data travels across the internet. When the paper refers to IP TV, IP distribution or streaming, it means TV delivered over broadband rather than broadcast.

A hybrid service – for example Freeview Play or Freely – combines:

• live broadcast channels received via an aerial or satellite; and
• extra or on-demand services delivered over broadband.

For viewers, the aim is that both feel part of one simple TV experience.

DVB-I is one of the standards that can support this hybrid world. It gives devices a common, internet-based way to discover broadcast and IP services and present them together in one channel list and programme guide, so viewers do not have to think about whether a service arrives via aerial, satellite or broadband. It is currently not a technical standard selected by broadcasters for use in the UK.

DVB-I – service discovery for broadcast and IP TV

DVB-I sits in the same DVB family as DVB-T and DVB-T2 but it does a different job. Rather than defining how TV signals are transmitted, it defines how devices find TV and radio services and how those services are described.

In simple terms, DVB-I is an internet-centric way for TVs, set-top boxes and apps to discover live TV services – and their programme information – over broadband or broadcast networks. A DVB-I client in the device downloads a structured “service list” from a server and uses it to build a familiar channel list and electronic programme guide (EPG). DVB

DVB-I aims to make linear TV delivered via the internet feel as straightforward and reliable as traditional broadcast TV. It plays a similar role for IP services as DVB-T/C/S do for broadcast – services are signalled and described in a standard way, so viewers do not need a separate app or user interface for each provider. DVB

For viewers, DVB-I can enable:

• one integrated list of services that can include both broadcast channels and streamed channels, with consistent channel numbers and branding; DVB

• a single EPG showing what is on now and next, regardless of whether the service is delivered via aerial, satellite or broadband;

• a more consistent experience across different devices – from living-room TVs to smartphones and tablets. DVB

Technically, DVB-I is defined in the DVB specification for Service Discovery and Programme Metadata for DVB-I Services, published as ETSI TS 103 770. It is normally used together with DVB’s adaptive streaming specification (DVB-DASH) when services are delivered over IP. DVB

DVB-I does not replace DTT or other broadcast standards. Instead, it provides a common “service layer” that can sit above broadcast and broadband delivery, helping hybrid platforms present a joined-up channel line-up and EPG.

B3.7 Standards, conformance and the D-Book

To make sure that TVs and set-top boxes from different manufacturers work properly with UK broadcast services, industry uses common specifications and tests.

• DTG (Digital TV Group) – the UK member organisation that brings together manufacturers, broadcasters, streamers and technology companies to agree technical standards.
• D-Book – DTG’s technical specification for UK digital TV products and services. It sets out how receivers should behave on DTT and hybrid platforms and is treated as the definitive technical reference in this paper.
• U-Book – DTG guidance that focuses on accessibility requirements such as subtitles and audio description.
• R-Book – guidance for aerial installers.
• DTG Testing – an accredited laboratory that checks receivers against the D-Book and platform requirements.

Manufacturers that use platform trademarks such as Freeview, Freeview Play or Freely must meet the relevant requirements so that consumers have a predictable experience.

B3.8 Help Schemes and filters

Previous major changes – for example digital switchover and the 700 MHz clearance – were supported by a Help Scheme for vulnerable viewers. This paper assumes a similar approach for any migration to an all-DVB-T2 network.

Typical features include:

• Who is helped – older people, disabled people, low-income households and homes that rely solely on DTT.
• What is offered – free or low-cost T2-capable adaptors or TVs, home visits to install equipment or adjust aerials, and filters where new mobile services cause interference.

The drafting group treats a funded, time-limited Help Scheme as a precondition for any move to DVB-T2-only broadcasting.

B3.9 Addressable advertising and Arqads

Traditional broadcast adverts are the same for everyone watching a channel at a given time. Addressable advertising allows different households to see different adverts in the same break, for example by location or household type, subject to data-protection rules.

Arqads is Arqiva’s own platform for enabling addressable advertising on broadcast and hybrid TV, including DTT. It lets broadcasters introduce more targeted advertising while still using reliable broadcast distribution.

B3.10 Future options – 5G broadcast and ATSC 3.0

The paper briefly notes other broadcast technologies being explored internationally:

• 5G broadcast – uses 5G technology in a broadcast mode to send the same content to many devices at once, more like TV broadcasting than one-to-one streaming.
• ATSC 3.0 (“NextGen TV”) – the new terrestrial TV standard in parts of the United States, similar in aim to DVB-T2 with modern codecs. It raises questions about tuners, encryption and carriage that are relevant to long-term UK planning.

These are not proposed for the UK within the scope of this paper but are watched as possible future influences.

B4. Plain-language glossary (A–Z)

Definitions are written for non-technical readers. Detailed technical behaviour is set out in the DTG D-Book and related specifications.

Term	Explanation in everyday language
3G / 4G / 5G / 6G	Generations of mobile-phone technology. Each new “G” is generally faster and can carry more data than the previous one.
A3SA (ATSC 3.0 Security Authority)	Body that manages encryption and security for ATSC 3.0 services in the United States. Relevant here only as an example of how another country secures a new TV standard.
Addressable advertising	Adverts where different homes can see different messages in the same break, based on agreed data such as location, rather than everyone seeing the same advert.
Adaptor (set-top box)	Small box that connects to a TV so it can receive newer broadcast standards such as DVB-T2 without replacing the TV itself.
Arcom	The media regulator in France, mentioned in international comparisons.
Arqads	Arqiva’s addressable advertising system for broadcast and hybrid TV, enabling targeted adverts on platforms such as Freeview.
Arqiva	The company that operates the UK’s main TV and radio transmitter network and manages many DTT multiplexes.
ATSC 1.0 / ATSC 3.0	Digital TV standards used in the United States. ATSC 1.0 is the older standard; ATSC 3.0 (NextGen TV) is the newer one with better compression and extra features.
Broadcast	Sending the same signal to many people at once over the air or satellite, instead of individual streams over the internet.
Broadband	High-speed internet connection to the home, usually over fixed lines (fibre or copper) or sometimes via fixed-wireless networks.
CAI (Confederation of Aerial Industries)	UK trade body for TV aerial and satellite-dish installers.
Catch-up / video-on-demand	TV programmes you choose to watch at a time that suits you, rather than when they are broadcast, via apps such as BBC iPlayer or ITVX.
Codec	Short for “coder–decoder”. Software or hardware that compresses video or audio for transmission and then decompresses it in the receiver.
COM mux (commercial multiplex)	A multiplex that mainly carries commercial channels and is funded commercially, not as part of the core PSB carriage.
Comux / Multiplex L	Company that operates the Local TV multiplex (Multiplex L), which carries local TV services and some additional national channels.
DAB (digital audio broadcasting)	Digital radio system used in the UK and other countries. Mentioned for context when comparing TV and radio platform changes.
D-Book	DTG’s technical rulebook for UK digital TV receivers and services. Treated in this paper as the definitive specification for UK digital TV.
DCMS / DSIT	Department for Culture, Media and Sport, and Department for Science, Innovation and Technology – the government departments responsible for media and communications policy.
Digital switchover (DSO)	The 2008–2012 programme when analogue TV was turned off and the UK moved fully to digital terrestrial TV.
Digital terrestrial television (DTT)	Digital TV transmitted from masts on land and received via an aerial – the technology behind Freeview.
Direct-to-home (DTH)	Satellite TV that goes directly from satellite to a dish on a home, such as Freesat or Sky’s satellite services.
DRM (digital rights management)	Technology used to control how digital content can be accessed and copied, for rights-protection reasons.
DTG (Digital TV Group)	The Digital Television Group (DTG) is an independent Research and Technology Organisation (RTO) established by industry in 1995 to specify the UK requirements for Digital Terrestrial Television. For more than 25 years it has been central to driving digital TV innovation in the UK. From driving the digital TV switchover to making interactive TV happen, rolling out on-demand TV, and introducing HDTV and UHD TV. The DTG works with the entire sector on the future of television – embracing the convergence of content and networks to efficiently deliver video to all screens, across all devices, in all formats. It delivers evidence-based technical research, demonstrators, trials and test-bed projects in the fields of digital television, digital switchover, spectrum coexistence, 5G broadcast, streaming and IP switchover for government and Ofcom. DTG working groups bring together members from all the critical sectors in digital media technology to work closely with our expert technical teams on the burning issues and horizon scanning. This includes publishing the D-Book each year, the universally deployed technical design and test requirements of UK digital terrestrial television distribution and reception.
DTG Testing	Independent, ISO17025 accredited laboratory that tests TVs and boxes against the D-Book and platform requirements such as Freeview and Freely.
DVB-I DVB-T	Is a standard way for devices to discover and list TV channels and programmes delivered over the Internet (and broadcast), so that to viewers it all just looks and behaves like ordinary television. It sits alongside DVB-T, DVB-S, and DVB-C; Terrestrial, Satellite and Cable. First-generation standard for digital terrestrial TV. Less efficient than DVB-T2 and used mainly for older SD services.
DVB-T2	Second-generation, more efficient standard for digital terrestrial TV. Allows more channels or higher-quality pictures using the same spectrum.
EPG (electronic programme guide)	The on-screen TV guide showing channels and what is on now and next, usually for several days ahead.
Everyone TV	Company jointly owned by the BBC, ITV, Channel 4 and Channel 5 that manages the Freeview, Freesat and Freely platforms, including branding, EPG rules and some technical coordination.
Filter (interference filter)	Small device fitted between an aerial and a TV or box to block unwanted mobile signals that might otherwise interfere with TV reception.
FM	Analogue radio broadcasting system. Some countries have switched from FM to DAB and IP radio.
Freeview	Brand name for the UK’s main free-to-air TV service via an aerial, based on DTT.
Freeview Play / Freely	Hybrid Freeview platforms that combine live broadcast channels with on-demand and IP services in a single interface.
Freesat	Free-to-air TV platform delivered via satellite rather than an aerial, often used where terrestrial coverage is weaker.
Guard interval	Small timing “gap” in a digital signal that helps receivers cope with reflections and timing differences, especially in single-frequency networks.
HD (high definition)	Higher-resolution TV picture with more detail and clearer images than standard definition.
Headend	Central technical facility where TV channels are encoded, compressed and combined into multiplexes before distribution to transmitters.
HEVC (H.265)	Modern video codec that gives about 40–50% better compression than MPEG-4 AVC at comparable quality. Widely used in streaming and newer broadcast services.
Help Scheme	Time-limited programme that provides equipment and support to vulnerable households during major TV platform changes, for example digital switchover or a move to DVB-T2.
Hybrid TV	TV devices or platforms that combine broadcast reception with broadband services, so viewers can watch both live channels and streamed content.
IP (Internet Protocol)	The standard set of rules for moving data across the internet. TV delivered using IP goes over broadband rather than traditional broadcast.
IPTV / streaming	Live or on-demand TV services delivered over an internet connection.
ISO/IEC 17025	International standard that sets requirements for the competence of testing laboratories, such as DTG Testing.
LCN (logical channel number)	The channel number used on the remote control and in the EPG, such as 1 for BBC One or 101 for BBC One HD.
Local TV multiplex (Multiplex L)	The DTT multiplex that carries local TV channels and some national services, operated by Comux.
Mbps (megabits per second)	Unit for measuring how much data can be carried each second – used here to describe multiplex capacity.
MPEG-2	Older video compression standard used in early digital TV, mainly for SD services.
MPEG-4 AVC (H.264)	Widely used video compression standard that is more efficient than MPEG-2. The proposed future DTT platform uses DVB-T2 with MPEG-4 AVC as its baseline.
Multiplex (mux)	A digital “bundle” of TV and radio services that share the same frequency. One multiplex can carry many channels.
NI Mux (Northern Ireland Mux)	A DVB-T2 multiplex in Northern Ireland carrying RTÉ One, RTÉ2, TG4 and an Irish radio service for viewers there.
NextGen TV	Consumer brand name for ATSC 3.0 in the United States.
Ofcom	The UK communications regulator. Licenses TV and radio services, manages spectrum and sets some technical rules for broadcasting.
On-demand	See catch-up / video-on-demand.
Platform	A complete TV environment such as Freeview, Freely, Freesat, Sky or Virgin Media – including technology, branding and viewer support.
PSB (public service broadcaster)	Broadcasters with public service duties, mainly the BBC, ITV, Channel 4 and Channel 5. They must meet obligations on news, UK content and coverage of nations and regions.
PSB multiplex	A multiplex that carries the main PSB channels and some of their portfolio services.
PSM (public service media)	The wider set of public service content, including both broadcast and online services.
Retune	The process where a TV or set-top box scans for channels again, typically after frequency changes or new channel launches.
Rooftop / indoor aerial	The antenna that picks up broadcast TV signals. Rooftop aerials generally provide better reception than small indoor aerials.
SD (standard definition)	Older, lower-resolution TV format. Acceptable on smaller screens but visibly softer on modern large TVs.
SFN (single-frequency network)	A group of transmitters using the same frequency and carefully timed so their signals add together rather than interfere, improving spectrum efficiency.
Spectrum	The range of radio frequencies used for services such as TV, radio and mobile. Managed by government and regulators.
Spectrum clearance	Moving existing users off a frequency range so it can be reused, for example shifting TV services to make room for mobile.
Streaming device / stick	Small device that plugs into a TV’s HDMI port and provides streaming services over broadband.
T2 set / T2 receiver	TV or set-top box that can receive DVB-T2 signals, and so is ready for future all-T2 DTT services.
Transmitter / relay	A transmitter is a mast that sends TV signals over a wide area; a relay is a smaller transmitter that fills coverage gaps.
U-Book	DTG guide that sets out accessibility requirements for UK digital TV, such as support for subtitles and audio description.
UHF (ultra-high frequency)	Part of the radio spectrum used for TV broadcasting; in the UK, DTT currently uses 470–694 MHz.
UHD / 4K (ultra-high definition)	Very high-resolution TV format with around four times as many pixels as HD.
UKAS	UK Accreditation Service – the national body that accredits organisations such as DTG Testing against standards like ISO/IEC 17025.
YouView	Hybrid TV platform that combines Freeview channels with on-demand apps, used by several broadband and pay-TV providers.