|A| |B| |C| | D| E| |F| |G| |H| |I| |J| |K| |L| |M| |N| |O| |P| |Q| |R| |S| |T| |U| |V| |W| |X| |Y| |Z|
A
Analogue Broadcasting - The traditional way of broadcasting television and radio. An analogue signal directly represents the pictures and sound. This is unlike digital broadcasting which operates by coding the pictures and sound into 'computerised' data.
Analogue Switch Off - The Irish national free to air analogue TV network provides a free access service to all or some of the national TV channels, RTÉ 1, RTÉ 2, TG4 and TV3. It is received through a rooftop aerial or 'rabbit's ears'. This network is being switched off in the on the 24th October 2012 and this switch off is referred to as analogue switch off.
Analogue Terrestrial TV channels - The analogue TV channels broadcast in Ireland and received via an aerial are RTÉ One, RTÉ Two, TV3, and TG4.
Aerial or Antenna– A metal fabrication designed to receive signals, in particular a TV aerial will receive TV signals within the frequencies it has been designed for.
Aspect Ratio - This defines the shape of a TV screen and is the relationship between the width and height of the screen. A standard TV set has an aspect ratio of 4:3. A widescreen set has an aspect ratio of 16:9, giving a 'letterbox' shape like that of a cinema screen. The programmes on most of the major TV channels are now broadcast in 16:9 format.
Audio Description - A spoken commentary on TV that describes what is happening on screen, particularly useful for visually impaired viewers. The commentary fits in between dialogue and describes action sequences, facial expressions, costume, scenery and so on.
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B
Broadcasting spectrum – the range of radio frequencies that may be used for broadcasting. A single radio frequency (RF) channel takes up a certain amount of frequency space. In analogue systems one programme service/TV channel occupies one radio frequency channel. In digital systems a number of programme services will occupy a single radio frequency channel. Thus compared to the analogue systems of the past, digital systems can deliver the same services using less radio spectrum.
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C
Cable TV – Broadcast signals are pulled off-air from terrestrial or satellite transmitters and distributed to receiving devices via co-axial or fibre cable. For digital cable, a decoder box is used to receive and decode any digital signals transmitted. Cable television was introduced in Ireland in the late sixties and is currently being upgraded to provide for digital transmissions.
Coaxial cable – A type of metal transmission cable containing two conductors where the outer conductor forms a cylinder that encloses the inner conductor. The two conductors are separated by air or some other insulator.
Compression – Term that refers to the reduction of the size of digital data by removing non critical information.
Conditional Access (CA) – Conditional Access systems restrict television program access to certain groups of users either because of concerns for privacy or the desire to collect revenue for the service. Providing conditional access requires secure encryption of the program content, secure decryption in a set-top-box for each viewer, and its embedded serial number that is registered in a central conditional access system database.
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D
Decoder - A device that turns digital signals back into analogue sound and picture signals. It may come in a set-top box, or be built into a TV set or PVR.
Digitag – Is an international forum promoting the introduction and implementation of digital terrestrial television services using the standards developed by Digital Video Broadcasting (DVB). DigiTAG members include broadcasters, manufacturers, broadcast operators and Broadcast regulators and frequency spectrum administrations. More information can be found at http://www.digitag.org/.
Digital - The new way of broadcasting television and radio. A digital signal codes the pictures and sounds into 'computerised' data. This allows the information to be transmitted more easily and more efficiently than analogue signals. The signal then has to be turned back into pictures and sounds by a decoder.
Digital Aertel – The launch of SAORVIEW provides for the introduction of a digital version of teletext (Digitext). Digital teletext offers the services provided by traditional teletext but with enhanced features such as faster page transitions, more aesthetically pleasing page layout, multiview capabilities and the possibility of regionally specific pages
Digital Freesat Service - Freesat is the trademark name for free to air digital satellite television services delivered to the UK market. It was established to complement Freeview – the UK free to air Digital Terrestrial Television platform.
Digital Tuner – The digital tuner serves as the decoder required to receive and display digital broadcasts. It can be included inside a TV or set top box.
Digital Switchover- The process of switching from analogue to digital broadcasting. Most European countries plan to achieve digital switchover by the end of 2012.
Digital Terrestrial Television (DTT) - Digital TV that is received off air via a standard roof top or set top aerial.
Digital Television - A new technology for the broadcasting of television signals. Signals are delivered to your television in streams of data, whereas analogue signals are transmitted by continuously varying radio waves. Compared to analogue broadcasting, transmitting digital television signals is more effective and provides a sharper picture, improved sound, and additional features to television viewers
DTT Receiver - This is the device that processes the incoming signal from the DTT transmitter and turns it into a format which can be displayed on the TV. It can take the form of a set top box or may be integrated into the TV itself. The essential role of the DTT receiver is to receive, decode and decompress digital data to produce audio and video signals that can be displayed. It is a custom computer system whose processing power can vary considerably depending on the functionality and sophistication of the receiver.
Downlink - A signal sent down from a satellite to the ground.
DVB - Digital Video Broadcasting, a European consortium for the standardization and deployment of digital television via terrestrial broadcast and satellite.
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E
Electromagnetic Spectrum - Energy exists in many forms, one of which is the electromagnetic spectrum. The electromagnetic spectrum comprises radio waves, infra-red, visible light, ultra-violet, gamma rays. Radio waves cover the frequency range from 3kHz to 300GHz.
Electronic Programme Guide (EPG) - software built into a set-top box that gives on-screen listings of what's on TV now and for a number of days or weeks ahead. You can use the EPG to go straight to a programme you want to watch or to select something to record.
Encryption - the scrambling of programmes or channels to ensure that only authorised viewers can access them. Usually programme services are encrypted as part of pay-TV or subscription TV services.
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F
Free To Air (FTA) - A programme or service that you don't need to pay a subscription to receive.
Freeview - The UK free to air digital terrestrial television service.
Freesat – The UK free to air broadcast satellite service.
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H
HDTV or High Definition Television provides much better resolution and picture quality than standard definition TV. It reduces the graininess of the picture by reducing the pixel size and images on the screen have a greater fluidity of movement. HDTV can only be carried on a digital TV platform. A HD TV has up to four times as many pixels (dots on the screen) as a standard-definition TV.
HDMI cable- High-definition multimedia interface: a digital connection using a single cable for high-quality video and audio. A HDMI cable is required to view HDTV.
HDTV Tuner- (also known as Decoder or Receiver)- a device capable of receiving and decoding HDTV signals.
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I
IDTV (or iDTV) - Integrated digital television: a TV set with a built-in digital TV receiver. This means a viewer does not require a set top box to watch digital terrestrial television (as long as they are covered by the service and have the correct aerial as needed)
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L
Letterbox - The name given for the way that a widescreen picture (16:9 ratio) is displayed on a standard TV screen (4:3 ratio) with black bands at the top and bottom.
Line, 405 - 405 Line ((The 405-line Monochrome Analogue Television Broadcasting System) describes a very early black & white TV system.
Line, 625 - 625 lines is the number of horizontal lines in a PAL tv signal. Typically 576 of these are used to make up the image seen on screen. It is in effect the "vertical resolution" of the analogue signal.
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M
MHEG – A standard for multimedia scripting, display and user interaction which was developed by the Multimedia and Hypermedia information coding Expert Group. It is suggested as an alternative to HTML and Java for enhanced television services.
MHP - Multimedia Home Platform (MHP) is a standard within the DVB for enhanced television. It defines a generic interface between interactive digital applications and the terminals on which those applications execute. It supports many kinds of applications including electronic program guides, information services, synchronous enhancements, e-commerce and secure transactions. It requires a Java run-time engine within the set-top-box, allowing complex applications to be developed.
Middleware - Middleware is a layer of software that runs on top of set top box operating systems (OS) creating a consistent environment to run application software over a wide variety of set top boxes.
MPEG - The Moving Picture Experts Group, a technical standardisation group that has developed international standards for compressed digital video and audio. MPEG-1 provides resolution up to 1/4 of standard definition video, at bit rates up to roughly 1.5 Mbits/second. MPEG-2 provides a family of compression profiles and levels, including ones for High Definition Television. MPEG-4 provides an even higher range of resolution options, plus the ability to include image objects. MPEG-4 is the standard used for the transmission of content in Ireland due to its enhanced compression ability and the large quantities of information contained in High Definition (HD) signals.
Multipoint Microwave Distribution Service (MMDS) – MMDS is a an alternative method of providing cable television programming choice in less populated areas where the provision of a cable connection to each house is not cost effective. Signals are in the form of high frequency radio waves that are sent over the air and received using an appropriate type of rooftop aerial. It is sometimes called wireless cable.
Multiplex (mux) – A multiplexer is a device that takes multiple inputs and combines them in a single output signal for transmission. A demultiplexer reverses the process. In practical terms several different digital radio and TV programmes might be combined in a single frequency band signal.
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N
Near universal coverage – It is very difficult for a broadcasting service to offer coverage at all geographical locations in the country. It is anticipated that DTT will provide coverage to about 98% of the population.
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O
Overspill - Some regions of Ireland such as areas in the southeast and near the Border can receive UK terrestrial stations such as BBC1 and UTV through an ordinary aerial - a phenomenon called overspill.
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P
Pay TV – Television service that requires users to pay a subscription for access to their programmes. Pay TV providers in Ireland are SKY and UPC.
Personal Video Recorder (PVR) - Also known as a DVR (digital video recorder) or PDR (personal digital recorder). It records TV programmes digitally on to a hard disk (like saving information on a computer), instead of on video tape or DVD. It has an electronic programme guide built in, and allows you to pause and 'rewind' a programme while you are watching it.
Pixels – Picture element: Pixels are tiny samples of video information, the "little squares" that "add up" to an entire picture on the TV screen. Typically thousands of pixels make up a picture and the more pixels there are the better the quality of the picture. Standard screens have 625 lines of pixels, HD screens have 720 or even 1080 lines. This gives a clearer, sharper picture with much more detail.
Platform - In broadcasting, a system for delivering TV and radio services. For example, digital TV is delivered mainly on terrestrial, satellite, cable and broadband platforms. SAORVIEW is delivered over a terrestrial platform.
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R
Rabbit Ears - The term describes an antenna that sits on top of your television set. The antenna sticks out in a V-shaped that is adjustable in length and angle.
Radio Waves - Part of the electromagnetic spectrum used for wireless communications services including broadcasting. Radio waves cover the frequency range from 3kHz to 300GHz.
Receiver – The general term given to consumer broadcast equipment that receives signals from a transmitter and allows you to see and/or hear TV or radio broadcasts. TV’s, digital TV set-top boxes and radios are all examples of receivers.
Relay – The name given to a low-power transmitter that receives signals from a main transmitter and retransmits them to a localised area.
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S
Satellite TV- Satellite broadcasting services are received through geostationary satellites above the earth. The satellite receives signals transmitted from an uplink facility on the ground and broadcasts them so that they may be received by a satellite dish antenna connected to a satellite receiver at the TV viewer’s premises. Satellites have a wide coverage area and a single satellite can cover many countries.
Scart - A Scart lead has a large, rectangular, 21-pin plug at each end. It is the most common way to connect equipment such as TVs, video recorders, DVD players and set-top boxes.
Set top box – An electronic device which can receive and decode digital TV signals so that they can be displayed on an analogue TV.
Smart card - Also called a conditional access viewing card: a plastic card inserted into a slot in a set-top box or TV that decodes signals and allows you to receive encrypted digital services.
Standard Definition (SD) – A level of screen resolution (no of pixels on the screen) that produces a picture quality comparable with good quality traditional analogue TV reception. Standard Definition screens have 625 lines of pixels on the screen.
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T
Terrestrial Television – Television broadcasts, over radio waves, which are transmitted from a transmitter located on the earth – generally on a mountain or hill site and intended for direct reception by the general public.
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U
Uplink - A signal sent up to a satellite from the ground.
UHF - Ultra High Frequency (UHF) designates the ITU Radio frequency range of electromagnetic waves between 300 MHz and 3 GHz (3,000 MHz).
V
Very high frequency (VHF) is the radio frequency range from 30 MHz to 300 MHz. Frequencies immediately below VHF are denoted High frequency (HF), and the next higher frequencies are known as Ultra high frequency (UHF).
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W
Widescreen - TV pictures with an aspect ratio of 16:9 that gives shape like that of a cinema screen. The programmes on most of the major TV channels are now in widescreen format
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