Jargon buster

There are a lot of new terms and abbreviations around digital TV. Here’s what some of them mean.

3D Television
Some TV programmes and some Blu-ray discs are available in 3D format. To experience these you will need a 3D TV with special glasses and for Blu-rays you will also need a 3D ready Blu-ray player.

ADSL
Asymmetric Digital Subscriber Line (ADSL) is the technology that brings broadband Internet into our homes over the phone line. Increasingly it is also a way of receiving television and video services, such as VOD, all over an ordinary telephone line

Aerial distribution amplifier
This allows you to divert your TV aerial signal to several rooms. You connect the aerial lead to the input socket and then run extension leads from the output. Because the signal is amplified it can be split without becoming weaker. Do buy a good quality distribution amplifier – for around £25 – so it won’t distort or amplify the signal too much. If you want to split it just two ways, and have a strong signal from your rooftop aerial, you may not need to go to the expense of one of these. You could use a much cheaper Y splitter.

Analogue
The way our television is transmitted and recorded traditionally before it goes digital. It is called analogue because the electrical signal ‘represents’ the picture and sound signals rather than being coded into a series of ‘1’s and ‘0’s .

Audio description
Audio description describes what is happening on screen for those who have difficulty seeing. It is an additional narration that fits between dialogue and describes action sequences, body language, facial expression, costume and scenery. Audio description is broadcast only on selected programmes and currently only a few iDTVs and digital boxes on the market can receive and decode these signals.

Assisted Retune
This is a feature available on a few new Freeview set top boxes that is designed to help you retune following a digital switchover event. These boxes automatically prompt you to initiate a retune at the required time.

Bandwidth
We are told TV signals are transmitted at certain frequencies, but in fact they spread a little either side of the frequency. The amount of spread is called the bandwidth. With digital, the greater the bandwidth, the more digital data that can be sent. More data can give the broadcaster a choice - like better picture quality or more channels in their allocated bandwidth. Similarly, they can choose to allocate more or less bandwidth to data service and so speed up or expand the EPG and teletext service.

Broadband
A transmission with high bandwidth, so the data is delivered quickly. The term broadband is usually associated with Internet access (eg ADSL or cable) and for this application it usually means faster access.

CEC
See HDMI.

CRT
Cathode Ray Tube. A CRT TV is a conventional ‘TV-tube’ television. Bulky and heavy compared to the latest flat panel TVs, but still capable of producing high quality pictures.

DAB
Digital Audio Broadcasting - the DAB service is radio’s equivalent of digital TV. It gives interference-free reception and has room for extra stations as well as all the usual ones. It is available over most of the country. Personal, portable, tabletop and car radios are available for DAB. Many radio stations are also broadcast alongside the digital TV service, so can be received on digital TV boxes and iDTVs as an alternative, less portable, alternative to DAB.

DSO
Digital switchover by the terrestrial broadcasters - from analogue to digital. You will need to retune your digital TV or box in most regions during DSO See Retuning.

DTT or DTTV
Digital terrestrial television transmitted through an aerial. In the UK this includes the Freeview service (which includes the traditional terrestrial channels, BBC1, BBC2, ITV1, Channel 4 and Channel 5 and the new BBC, ITV and Channel 4 services) and additional commercial free and subscription services.

DTR
Digital Television Recorder is a smart digital receiver that records programmes to a hard drive (like a computer saves information) or a DVD disc instead of on a video tape. Programmes you want to record can be selected directly from the on-screen TV guide / EPG. See test reports for results on the DTRs we have assessed.

DTV
Digital television.

DVB (DVB-C, DVB-S, DVB-T)
Digital Video Broadcasting - a European standard for digital television technology: DVB-C for cable, DVB-S for satellite and DVB-T for terrestrial.

DVD
Digital Versatile Disc - though they may all look the same, DVD discs come in many forms (hence the word versatile). The most popular (usually simply referred to as DVDs) are discs containing pre-recorded films, concerts or music videos. Other formats include DVD +/-R, DVD+/-RW and DVD-RAMs, which can be used at home to record TV programmes or computer files.

This logo is used on information to help consumers make the right choices about digital switchover.

This logo certifies that products and services have been designed to continue to work after digital switchover.

EPG
Electronic Programme Guide - the on-screen TV guide, a listing of TV channels and programmes, available for terrestrial, satellite and cable digital TV. You can use it to switch to the programme you want, or to select a programme to record. The information is sent by the broadcasters with 7 to 8 days worth of programming. Different brands of iDTV or digital box may display this information in different ways.

Freeview
The main UK digital terrestrial television service that is transmitted through an aerial. No subscription is required. Additional subscription services are also available, see Top Up TV and Setanta.

FTA
Free-to-air - a programme or service that you don’t need a subscription to get. FTA digital TV is available from terrestrial and satellite services.

HDMI
A digital audio and video connection that is capable of transmitting both standard and high definition TV signals. Typically used for connecting a “Freeview HD” or a “Freesat HD” set top box or a Blue-ray player to an “HD Ready” TV. Some standard DVD and set top boxes players can also be connected via the HDMI leads but this does not result in an HD picture. Some more advanced HDMI connections have a system called CEC allow your TV remote control to also operate the connected devices.

High Definition TV (HDTV)
Gives you a crisper picture and the opportunity of better quality sound than standard definition TV. UK HDTV programmes are now available from

• freesat from BBC and ITV (non-subscription satellite)
• Sky (subscription satellite)
• Virgin (cable)
• Freeview (aerial) in some areas

HD Ready TV
A TV that has a screen resolution (of at least 720 horizontal lines) good enough to display high definition TV programmes and high definition discs (HD-DVD and BluRay).  But for HD TV programmes you will still need a set top box or digital TV recorder with a built in HD tuner to receive them.

HD Ready 1080p of 'Full HD' TV
TV that has a screen resolution (of at least 1080 horizontal lines) excellent for high definition TV viewing.  But you will still need a set top box or digital TV recorder with a built in HD tuner to receive the HD programmes.

HD Tuner
Allows you to receive high definition TV programmes. Set top boxes and digital TV recorders with built in HD tuners are now available for subscription and non subscription services via an aerial, satellite and cable. You will also need a TV capable of displaying HD pictures (see 'HD Ready TV' and 'Full HD' TV above). TVs are also now available with built in HD Tuners (see HD TV below)

HD TV
A TV that receives and displays high definition TV channels using its own built in HD tuner.

iDTV
Integrated Digital Television - a TV with a built-in digital receiver. It can be either a conventional CRT TV (although these are now rare) or one of the new flat panel LCD TVs.

Interactive
This covers any system where the user can choose extra services or respond to events. For digital TV it usually refers to extensions to the traditional teletext service. For instance, you can select and watch a particular sporting event from a multi-screen selection, find out more information about a TV programme. For satellite and cable services it can include cast a vote, or take part in a quiz.

Internet TV. This is a TV that connects to you home network and to the Internet. The connection to the network may be via a wired (Ethernet) cable or via WiFi. The TV will typically access a range of selected Internet features such as BBC iPlayer and services such as You Tube, Flickr, etc. For more information see our FAQ on internet TV.

IPTV
Internet protocol TV - a TV service delivered over the internet by phone line or cable. As it is via the internet, it means you can 'tune in' to selected TV or radio stations or programmes from anywhere in the world, but quality may not be as good as dedicated cable or phone line services such as Video on Demand (VOD) .

LED - Light emitting diodes
An LED TV is one where the screen consists of an array of many LED semiconductor lamps. These types of screen are not generally available on the consumer market.  They are typically used for very large screens found in public places and produce a bright image that can be seen at a distance.

LCD Liquid Crystal Display
LCD TVs are the most common type of flat panel television. All screen sizes above 26” are suitable for displaying HDTV.  Conventional LCD TVs use a form of fluorescent tube lamp backlight to illuminate the picture on the screen. Models that instead use semiconductor LED lamps for the screen’s backlight illumination are called “LCD TVs with LED backlights”. These generally provide better image quality, lower energy consumption and thinner televisions than conventional LCD. Though sometimes advertised as “LED TVs” they are different from a true LED TV - which use a different technology. (see also LED  and Plasma).

Modulator
An electronic gadget built into some set top boxes and digital TV recorders that allow it to be connected to a TV using an aerial lead instead of the preferred SCART lead. It is useful for very old TVs with no SCART socket, but it means slightly lower picture quality and mono sound. You can also buy external modulators from specialist electronics shops that can be used with any set top box.

MPEG
Motion Picture Experts Group - coordinates standards for the digital image processing used for broadcasting digital TV. They have developed several technical standards including MPEG2, as used for standard definition digital television and MP3 used for audio recording.

Multiplex
A digital TV multiplex is created by bundling together a group of digital TV stations so that together they fit into one broadcast channel. On analogue TV each TV station occupied one whole channel. With digital TV it is possible to multiplex four or five or more TV or radio stations into one of these channels.

Pay-per-view
You pay for particular films and sporting events on top of subscriptions to satellite or cable/phone line television.

PC card / adapter
You can turn your computer into a digital TV and watch programmes on its screen. For this you need to either install a digital TV PC card (this means getting inside the computer) or, if you have a modern PC with a fast USB-2 socket, you can plug in a digital TV USB adapter. You use the supplied software to tune in and watch TV.

Plasma
A plasma TV is a particular type of flat panel TV. They are popular for larger screen TVs (such as 42” or greater). Broadly speaking, plasma televisions give good picture quality, comparable to LCD TV, the main alternative. All recent plasma TVs are suitable for displaying HDTV.

Platform
A general term for the way of delivering or receiving digital television. Typical platforms are terrestrial, cable, satellite and TV delivered over a telephone line.

PVR / hard drive digital TV recorder
Personal video recorder - commonly called hard drive digital TV recorder - is a smart digital receiver that records programmes to a hard drive (like a computer saves information) instead of on a video tape. Programmes you want to record can be selected directly from the on-screen TV guide / EPG . See test reports for results on the digital TV recorders we have assessed. PVRs also allow you to pause and rewind live TV. The better PVRs incorporate twin tuners that allow you to record one programme while watching another.

Red button
One of the four colour coded buttonson your remote control for selecting teletext and other interactive television services. For interactive features, broadcasters often prompt you on screen when to press the red button.

Regional Preferences
This feature is designed to help you when you tune in your TV or box in an area that is served by more than one transmitter. During the tuning in process it offers you the choice of transmitters so you can select the strongest signal, the most channels or select your preferred TV region.

RGB
Red Green Blue. This is an analogue video signal format that provides the best quality standard definition audio and video signals via a SCART lead. RGB is generally used by digital TV set top boxes and DVD players. Other video signal formats – such as plain “video” used by analogue TV are lower quality than RGB.  

SCART
A common way of connecting one TV product to another. It connects the picture and stereo sound in one plug. A fully-wired SCART cable can carry RGB signals. Very old TVs and some portable TVs may not have a SCART socket, so for these you will need a set top box that incorporates a modulator so that you can connect the set top box using an aerial lead.

Setanta Sports
A pay-TV company which provides extra sports channels and programmes on digital terrestrial TV. To receive the service, your digital TV equipment must have a slot or hole to take the Setanta viewing card or module respectively. All iDTVs should have this but not all STBs do.

STB
Set Top Box. The equipment that receives digital television and converts it so it can be received on an existing (analogue) TV or VCR.

Switchover
The name used when broadcasters switch from analogue to digital by switching off the analogue transmitters. At this time you will have to have a digital TV (iDTV) or digital box to carry on watching TV. In most areas, if you are already receiving digital Tv you will have to retune your TV or set top box. See retuning.

Terrestrial TV
TV transmissions –analogue or digital - that are broadcast over the air directly to your TV aerial.

Top Up TV
A pay-TV company which provides extra channels and programmes on digital terrestrial TV. To receive the basic service, your digital TV equipment must have a slot or hole to take the Top Up TV viewing card or module respectively. All iDTVs should have this but not all STBs do. New subscribers to Top Up TV get their newer service called Top Up TV Anytime. This requires their special digital box that downloads extra programmes overnight. See our test report on the Thomson DT16300-16 recorder that delivers Top Up TV.

VCR
Video Cassette Recorder - the machine you have probably been recording and playing video tapes on for years. It records the analogue TV signal in fairly low quality. Because a VCR has only an analogue tuner built in, you need to use it with an external STB to record digital TV.

Video sender
This is a radio-transmitting device to distribute your TV picture and sound all around your house. It's made up of a transmitter (sender) and receiver. The sender connects to the back of your TV, set top box, VCR or DVD player (usually using a SCART output socket). The receiver connects to your second TV, for example, and picks up the transmitted signal in another room. By buying extra receivers you could pick up the signal in several other rooms. A video sender can also transmit back remote control signals so you can control the sending equipment. The main drawback of this distribution system is that you can view only the same programme on both the sending and receiving TV.

VOD
Video on demand - for a fee, films and programmes you want to watch are delivered when you want to watch them. You can choose from a large library of films or programmes. Tiscali Homechoice offers this service together with regular digital TV channels via ADSL. BT Vision also supply a VOD service via ADSL, combined with a Freeview STB. A similar system, sometimes referred to as NVOD (near video on demand) is the Box Office service offered by Sky where you can choose from a small number of films, though you may have to wait up to an hour for your film to start.

Widescreen
The ratio of the width to the height of a widescreen TV picture is 16 to 9, often called 16:9 format. Nearly all major TV channels now make and broadcast their programmes in this widescreen format. Older programmes were in the narrower 4:3 format. If set up correctly, a widescreen TV and set top box should display the picture on your screen in 16:9 or 4:3 as appropriate for the programme. Films often have even wider formats. An older standard 4:3 TV and set top box combination usually means the sides of a widescreen picture are cropped.

Y splitter
This is a simple gadget designed to split your rooftop TV aerial two ways. You plug your aerial cable in one end and then run two extension leads from the output sockets. Because it splits the signal without amplifying it, you will end up with two weaker signals. But this should not be a problem if you have a good strong signal to start with. These splitters won't work for weaker signals, or if you want to split your signal more than two ways. Then try an aerial distribution amplifier.