The technical language used to describe the equipment and procedures necessary for the UK Digital TV Switchover can seem very intimidating and confusing. Below is a list of important terms relating to the switchover, together with simple descriptions to help you understand what it's all about. For more information on the UK Digital TV Switchover, please visit the DigitalUK website.

Aspect Ratio

The relationship between the width and height of a television screen that defines its shape. Standard TV sets have an aspect ratio of 4:3, i.e. four units wide by three units high. For example, if the screen is 24 inches wide it will be 18 inches high. Widescreen TVs have an aspect ratio of 16:9 which gives a ‘letterbox’ shape like that of a cinema screen.

Audio Description

Particularly useful for visually impaired viewers, a spoken commentary describes what happens on screen between dialogue, including action sequences, facial expressions, scenery, costumes and so on.

Bandwidth

The range of frequencies used for transmitting a signal. Digital broadcasting takes up much less bandwidth than analogue which allows extra channels, services etc. to be broadcast.

Broadband

A system or circuit that carries signals over a wide range of frequencies or bandwidth. The wider the bandwidth, the more information that can be carried. Broadband internet, for example, gives you a high-speed connection suitable for downloading audio, video etc.

CRT

Cathode Ray Tube – the standard type of large-bodied TV set.

DAB

Digital audio broadcasting: the transmission system used for digital radio.

DCAB, D-CAB

Digital Cable: digital TV received via a cable connection.

Decoder

A device that unscrambles digital signals and turns them back into sound and pictures. A decoder may be a set-top box, or be built into a TV set or PVR.

Digibox

A digital set-top box.

Digital

The new way to broadcast TV and radio. A digital signal codes the pictures and sound being broadcast into computerised data. The signal is then turned back into pictures and sound by a decoder.

DLP

Digital Light Processing: used in rear-projection flat-panel TV screens.

DOG

Digital on-screen graphic: a channel identification logo, for example, usually seen in the top left-hand corner of the TV screen.

DSat, D-SAT

Digital Satellite: digital TV received via a satellite dish.

DTT

Digital Terrestrial Television: digital TV received via a standard aerial.

DVB

Digital Video Broadcasting, the European standard for digital TV technology.

DVD

Digital versatile disc, or digital video disc: DVDs give better picture and sound quality than video cassettes and can store more than CDs. They can be used in DVD players and recorders and also in computers, though there are different, often incompatible formats.

DVI

Digital visual interface: a digital connection for high-quality video, suitable for HD TV.

DVR

Digital video recorder: known more commonly as a PVR (personal video recorder), this records TV programmes digitally on to a hard disk (like saving information on a computer

EPG

Electronic programme guide: provides on-screen listings of what’s on, often for a number of days or weeks ahead, depending on the digital service you have.

Free to air (FTA)

A subscription free programme or service.

Freeview

The company that supplies the UK’s free digital terrestrial TV service.

HD TV

High-definition television: has four times as many pixels (dots on the screen) as standard-definition TV. This gives a clearer, sharper image with much more detail. HD TV also has better quality sound.

IDTV

Integrated digital television: a TV set with a built-in digital TV receiver that can receive Freeview channels without a separate set-top box.

Interactive TV

Features added to TV programmes that provide extra information, allow you to join in with things like quizzes or make choices about what you view.

LCD

Liquid crystal display: the picture is displayed on a flat-panel screen. LCD is particularly suitable for large TV screens and good for HD TV.

PDR

Personal digital recorder. See PVR.

Pixel

Short for picture element: a single dot on a TV screen (or computer screen or digital photo). Thousands of pixels make up a picture and the more pixels the better the picture. High-definition TV has up to four times as many pixels as standard-definition TV.

Plasma

The picture is displayed on a flat-panel screen, using gases behind the glass. Plasma is particularly suitable for large screens and good for HD TV.

Platform

A system for delivering TV and radio services in broadcasting. Digital TV, for example, is delivered mainly on terrestrial, satellite and cable platforms.

PPV

Pay-per-view: an individual programme or series that you pay to receive.

PVR

Personal video recorder (also known as a DVR [digital video recorder] or PDR [personal digital recorder]): Records TV programmes onto a hard disk, like saving information on a computer, instead of onto video tape or DVD. It has a built in electronic programme guide (EPG) and allows you to pause and ‘rewind’ a programme while you are watching it.

RF

Radio frequency: an RF connector is used to feed a TV signal from an aerial to a TV, video recorder, etc.

SCART

The type of connector most commonly used to connect TVs, video recorders, DVD players and set-top boxes.

Smart card

Also known as a ‘viewing card’: this plastic card is inserted into a slot in a set top box or TV set that decodes signals and allows you to received digital services such as Sky or Top Up TV.

STB

Set-top box.

Terrestrial

TV that is broadcast and received via an aerial.

VOD

Video on demand: a service that allows you to receive and watch selected TV programmes when you want to, rather than when they are broadcast.

Widescreen

TV picture that gives a ‘letterbox’ shape like that of a cinema screen, with an aspect ratio of 16:9.

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