John Cletheroe's
Freeview UK Digital Television Information

Freeview UK Digital Television System Glossary

All terms are described as used in the UK. Usage may differ in other countries.

Visitors to this page are encouraged to utilise Wikipedia for more extended explanations of most of the terms listed here.

IMPORTANT: To avoid any risk of damage to equipment, always switch off and disconnect the mains from all devices before connecting or disconnecting any signal cables (SCART leads, etc).

4:3

The conventional television aspect ratio, used before the introduction of widescreen.

14:9

The aspect ratio used for widescreen programmes on analogue.

16 QAM, or 16QM

See "QAM".

16:9

The aspect ratio used for widescreen programmes on Freeview.

64 QAM, or 64QM

See "QAM".

301 And 302

The BBC's so-called "interactive" channels, not actually interactive at all on Freeview. These channels often show extended live sports coverage, looping music videos, looping trailers, etc.

480i

480 lines, interlaced. A mode of operation commonly found on modern televisions.

480p

480 lines, progressive (i.e. not interlaced). A mode of operation commonly found on modern televisions.

576i

576 lines, interlaced. A mode of operation commonly found on modern televisions. This probably corresponds to 625 lines interlaced, the difference in the number of lines being due to the teletext and control information lines.

576p

576 lines, progressive (i.e. not interlaced). A mode of operation commonly found on modern televisions.

720p

720 lines, progressive. A mode of operation commonly found on modern televisions. Regarded by some sources as HD, but not by others.

1080i

1080 lines, interlaced. A mode of operation commonly found on modern televisions. Regarded by some sources as HD, but not by others.

1080p

1080 lines, progressive (i.e. not interlaced). A mode of operation commonly found on modern televisions. Generally regarded as HD, I think.

Analogue Text

A shorthand method of referring to the teletext services on analogue television. All text services are of course digital in nature.

Aspect Ratio

The ratio of the width to the height of a television picture or a television screen. Conventional televisions have an aspect ratio of 4:3. Widescreen televisions have an aspect ratio of 16:9. Some programmes are broadcast at 14:9. Some programmes are broadcast at different aspect ratios on Freeview to analogue.

ATT

Analogue Terrestrial Television. Conventional traditional television broadcast from ground-based transmitter masts.

BBCi

The BBC's digital text system. The equivalent of Ceefax, but BBCi has far less information content and is usually updated many hours behind Ceefax.

At one time the BBC's web site was also confusingly referred to as BBCi but this no longer appears to be the case.

CAM

Conditional Access Module. A card slot for subscription services such as Top-Up TV.

CBBC

A BBC channel for older children.

CC

Crown Castle, the company which operates most (or all) of the terrestrial television transmitters in Britain. Crown Castle administer one of the Freeview multiplexes. Update: Crown Castle are now known as National Grid Wireless.

Channel

  1. A physical UHF channel.

  2. A logical Freeview channel (BBC1, BBC2, etc). LCN means Logical Channel Number.

  3. On NTL cable television, the text facilities are organised into subject areas called channels (news, weather, travel, etc). The word "channel" is not used in this sense on Freeview.

CRT

Cathode Ray Tube.

DAB

Digital Audio Broadcasting (i.e. digital radio). Completely separate to DTT, although both systems transmit much the same collection of radio stations. In the UK, DAB is subject to poor technical quality and very high costs for receivers.

Decoder

A term occasionally used for a Freeview, cable or satellite television receiver.

Digibox

A Freeview, cable or satellite receiver.

Digital Aerial

There is no such thing as a digital aerial. The term is widely used by manufacturers, retailers and installers as a method of deceiving people into purchasing an unnecessary replacement aerial in order to receive Freeview. All aerials can receive both analogue and digital. However, if current analogue reception is poor then a better aerial may be required for Freeview, for example replacing an indoor or loft aerial with a rooftop aerial. A very small number of viewers will require a wideband aerial to receive Freeview but this is extremely rare.

Digital Text

A shorthand method of referring to the teletext services on digital television. All text services are of course digital in nature.

Digital UK

A government funded organisation whose role is to promote and publicise the changeover to digital television in Britain. Might be the same as Switchco.

DOG

Digitally Overlayed Graphic For example, a channel logo. Almost universally hated and despised by viewers. An excellent method of reducing viewer numbers for a channel.

I'm not sure whether digital text overlays, such as the equally hated "Press Red", count as DOG's.

DRM

  1. Digital Radio Mondial. A system by which digital radio transmissions can be made on medium wave.

  2. Digital Rights Management. Copyright and anti-piracy mechanisms.

DTG

Digital Television Group. An organisation which administers the technical aspects of the Freeview system.

DTT

Digital Terrestrial Television. Exactly the same as DVB-T. Freeview.

DVB

Digital Video Broadcasting. All forms of digital television, including Freeview, digital cable television and digital satellite television.

DVB-T

Digital Video Broadcasting - Terrestrial. Exactly the same as DTT. Freeview.

DVI

A method of connecting digital display devices. This term probably only applies to computers and their monitors, not to televisions.

DX

Long distance radio or television reception.

EBU

European Broadcasting Union. The organisation which coordinates the use of broadcasting frequencies across Europe, the interconnections between various countries, etc.

EPG

Electronic Programme Guide. A list of the programmes on each channel, which is displayed on the television screen. Freeview currently has an inherent "Now and Next" and 7-Day EPG, although in most cases broadcasters only load data for the current and following day. BBCi and Teletext text channels also offer programme listings.

ERP

Effective Radiated Power. A measure of the power of a transmitter.

"Filmed"

A term often still used, even when programmes are recorded electronically.

Filmic

A distorting effect, applied by broadcasters, so as to reduce video picture quality to that of film. The image appears grainy, slightly out of focus and with a poor contrast profile. According to some sources, some forms of HD recording can give the same awful appearance.

Freeview

The current UK digital terrestrial television service. The successor to OnDigital and ITV Digital.

FTA

Free-to-air. Free channels. Unencrypted.

FTN

Flextech Television Network A Freeview channel.

FTV

Free-to-view. Effectively the same as FTA, although technically there is a difference.

HD

  1. High definition. Anything beyond 625 lines.

  2. Hard disk.

HD Ready

Not ready to receive high definition transmissions. HD Ready televisions can display slightly higher resolutions than 625 lines but they lack the necessary tuner to receive them.

HDMI

High-Definition Multimedia Interface. A method of connecting HD equipment.

i

  1. As a suffix to a number, the stated number of lines, interlaced.

  2. "Press i", as used by the BBC, means press the green button on your remote control so as to cancel the "Press i" symbol.

  3. As a button on a remote control, "i" will display information about the currently selected channel, the current programme, and in most cases the following programme (i.e. "Now and Next").

IDTV

Integrated digital television. A television with a built-in Freeview receiver.

Interactive

  1. BBC usage: An additional channel used on an "as-and-when-required" basis for extended sports coverage, additional material as described in the following definition, or a continuous loop. The word "interactive" in this sense is both incorrect and misleading.

  2. BBC usage: Additional material on an extra channel, broadcast at the same time as a normal programme, adding an activity such as a competition, usually by means of the digital text system. The broadcasting of this type of material is extremely rare.

  3. ITV usage: A television programme with an associated premium rate phone call "competition" scam, a viewers' poll, etc; or a channel dedicated to premium rate phone call "competitions". Because most Freeview boxes do not have telephone connections, there is no risk of accidentally making an expensive phone call. A small number of Freeview receivers have an RS-232 interface but this is for connection to a computer as an alternative method of loading software upgrades, and for diagnostic purposes. It is not for connection to a modem.

  4. NTL usage: The digital television text systems.

Interlaced

See "Progressive" (the opposite of interlaced).

IPP

In-Programme Promotion (I think). The revolting habit of displaying an advertisement for a following programme within a programme. One of the methods by which broadcasters can annoy viewers greatly and drive them away.

IPTV

Internet Protocol Television. The transmission of television programmes in realtime at broadcast quality over the Internet. Not yet feasible in Britain.

LCD

Liquid Crystal Display (one type of flat panel, the other being plasma).

LCN

Freeview logical channel number. Very different to a physical channel number.

LNB

Low Noise Block. The device in a satellite dish which receives the signal. Not applicable to Freeview, since its signals are received with an aerial, not a satellite dish.

MFN

Multi Frequency Network. A system whereby transmitters with overlapping coverage areas transmit on different frequencies. At present all UK analogue and digital terrestrial television transmissions use an MFN system. See also SFN.

MHEG

Multimedia and Hypermedia Experts Group. The digital text system used in the UK.

MPEG

Moving Pictures Expert Group. I suspect this might be the encoding system used on Freeview but I'm not sure.

Multiplex

A set of logical channels (any mix of television, text and radio channels) transmitted as one physical UHF signal.

MUX

Multiplex.

Now And Next

Information about the current programme and the following programme, usually displayed with information about the currently selected channel and the date and time.

NTSC

National Television Standard Committee (or jokingly, Never The Same Colour). The system used to transmit colour information on the television systems of the USA, Canada, Japan, Mexico, Central American countries and some South American countries.

NVOD

Near Video On Demand. The availability of programmes as the viewer desires, but subject to delays before the programme starts. For example, programmes might only start on quarter hours.

OAD

On-air Download. The transmission of a new version of the software for one or more models of Freeview set-top boxes.

p (as a suffix to a number)

The stated number of lines, progressive.

PAL

Phase Alternating Line. The system used to transmit colour information on the television systems of the UK, most of mainland Europe, Australia, New Zealand, China, India, Middle Eastern countries and some African countries.

PDC

Programme Delivery Control. A system used with analogue television that was supposed to automate the recording of programmes with VCR's, even if the programme ran late. In practice broadcasters failed to operate the system consistently, making it useless. As far as I know there is no corresponding system with digital television.

Polarisation

Whether the aerial rods should be horizontal or vertical. In the vast majority of cases for reception from a main transmitter they should be horizontal and for reception from a relay they should be vertical. Polarisation allows two signals to occupy the same frequency with a minimum of interference.

"Press i"

An instruction to press the green button on your remote control, so as to cancel the "Press i" symbol.

"Press Red"

An instruction to press the green button on your remote control, so as to cancel the "Press Red" symbol.

Progressive

Not interlaced. All UK analogue and Freeview transmissions are interlaced. All signals applied to CRT's are interlaced. All signals applied to LCD's are progressive (the receiver converts from interlaced to progressive). HD transmissions on cable and satellite can be either interlaced or progressive, I believe.

PPV

Pay-Per-View.

PSB

Public Service Broadcaster. The definition of what constitutes a public service broadcaster is unclear. The BBC obviously qualifies, but according to some sources so do ITV and Channel 4.

PVR

Personal Video Recorder. A domestic device which records television programmes on a hard disk. Also referred to as a Tivo, although that is a specific trade name.

QAM or QM (usually prefixed with a number)

Quadrature Amplitude Modulation. The way in which Freeview signals are broadcast. The prefixing figure affects how many channels a multiplex can carry and how resilient the signal is to interference. The higher the figure, the more channels are possible, but reception will be less reliable (given the same transmitter ERP). Figures of 16QAM and 64QAM seem to be commonly quoted. QAM is frequently abbreviated to QM, for example 16QM and 64QM.

QVC

Quality, Value, Convenience A shopping channel.

SCART

The standard method of connecting standard definition television equipment. The initials stand for Syndicat des Constructeurs d'Appareils Radiorecepteurs et Televiseurs.

SD

Standard definition. 625 lines.

SDN

A member of the Freeview consortium. SDN administer one multiplex.

SECAM

The system used to transmit colour information on the television systems of France, Russia, most central Asian countries and some African countries.

SFN

Single Frequency Network. A system which allows transmitters with overalapping coverage areas to transmit on the same set of frequencies. See also MFN.

STB

Set-top box. A Freeview, cable or satellite television receiver.

Switchco

A government funded organisation whose role is to promote and publicise the changeover to digital television in Britain. Might be the same as "Digital UK".

TCM

Turner Classic Movies. A Top-Up TV channel which shows old films.

TDN

The Digital Network. An organisation (or possibly just a committee) involving all the Freeview multiplex operators.

Timesharing

The use of the same bandwidth by two or more channels, each broadcasting programmes on the same data stream for part of the day. In most cases each channel has a different Freeview channel number and a caption is displayed when programmes are not being transmitted.

Tivo

A trade name for a domestic device which records television programmes on a hard disk. More generally referred to as a PVR, Personal Video Recorder.

TMF

The Music Factory. A pop music video channel.

TUTV

Top-Up TV. A set of encrypted pay-tv subscription channels broadcast on the Freeview system. See note.

TX

Transmitter.

UHF

Ultra High Frequency (wavebands).

VoD

Video on Demand. The playing of television programmes on requested for individual viewers at times of their choosing, usually via broadband Internet. Perceived by many people as very likely to completely replace conventional television channels in the medium term future.

Wideband Aerial

An aerial which can receive signals across the entire UHF bands, whereas normal aerials are optimised for a particular part of the bands. A few small number of viewers will require a wideband aerial for Freeview but this is extremely rare.
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