glossary of terms

welcome to our smart home glossary of terms – in plain english!

Select a quicklink:  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

4:3 - the screen ration for a standard TV screen. For every four horizontal units there are three vertical ones, so a screen 16 inches wide will be 12 inches high.

5.1 - the number of audio channels used by surround sound formats such as Dolby Digital. The 5.1 channels comprise front left, front right, front centre, surround left, surround right and a dedicated bass channel, represented by the '.1.' Audio reproduction in 5.1 surround is commonly found on DVDs, especially on digital movie soundtracks.

6.1 - the number of channel used by the DTS ES sound format. It is similar to 5.1 with the addition of a surround centre audio channel.

802.11 - a wireless transmission protocol. It exists in a number of versions (labelled a to g) that run at different frequencies, giving different data transfer rates. Versions b and g are currently in the most popular frequencies in use, for wireless PC networks (WLAN).

16:9 - the screen ratio of a widescreen TV. For every sixteen horizontal units there are nine vertical ones, so a screen 24 inches wide will be 13.5 inches high.

A
ADSL - Asymmetric Digital Subscriber Line. A telephone line that provides broadband high speed data transfer. ADSL allows internet use as well as normal telephone simultaneously on the same line.

Amplifier – a device which can increase the output from a given input. An AV amplifier for example, will take the audio from a DVD player and deliver the audio soundtrack to the speakers in a home cinema system.

B
Bandwidth - the band of frequencies in a transmitted signal (for example a radio signal). Can also be used to refer to the capacity available in a communications network.

Blu-Ray Disc Format - a format developed by a group of the leading consumer electronics companies. It uses a new blue-violet laser technology, that claims to store up to 10x more data than on a standard DVD.

Broadband - generally defined as a connection that offers data rates of more than 128kb/s.

Bus - an electrical transmission system where all devices attached to the bus receive all transmissions sent through the system, at the same time. An audio bus would provide music to a range of speakers simultaneously for example.

C
Category 5 - (a.k.a. CAT5) – four pairs of twisted data cable, used to carry telephone, computer data, audio and video in a smart home installation.

CATV - Abbreviation for cable TV.

CCTV - Closed-Circuit Television.

Coaxial Cable (a.k.a. coax) - a cable with a central copper core, which is insulated (kept separate) from another conductive shield, and then wrapped in an overall jacket. Coaxial cable is typically used for video distribution of TV, satellite, video and CCTV images.

CRT - Cathode Ray Tube. The technology used in conventional television sets. CRT technology is also used in projectors.

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D
DECT- Digital European Cordless Telecommunication. DECT is a digital cordless telephone system, mainly used in residential market.

Digital Television - (DTV) digital television theoretically offers better quality pictures than normal analogue TV, The signal is encoded (scrambled) and translated for the consumer via a set-top box (STB) or hardware within an integrated television set (iDTV). DTV is available via satellite and cable through subscription, or free via terrestrial through a Freeview box. DTV offers the broadcaster the possibility of more channels, as well as interactive services.

Dolby Digital - a digital surround sound system developed by Dolby laboratories. It offers from 1 to 5.1 channels of audio reproduction: front left, front right, front centre, surround left, surround right and a dedicated Low Frequency Effects (bass) channel, represented by the '.1.' DVD players with Dolby Digital capability can provide a backward-compatible mixdown of the five main channels to four for Dolby Pro-Logic playback.

Dolby Pro-Logic (a.k.a. Dolby Surround) - a surround sound system developed by Dolby Laboratories. It offers four channels of audio reproduction: front left, front right, front centre and a mono surround channel, usually delivered by two surround speakers located behind the listening position.

DLP - Digital Light Processing - a way to project and display video signals using millions of microscopic highly polished mirrors to generate the image. Close spacing of the micromirrors causes video images to be projected as seamless pictures in very high levels of detail. Many modern home cinema projectors use this technology.

DVD - Digital Versatile Disc (a.k.a. Digital Video Disc). An optical disc that has two sides and can store 4.7GB of data per side, i.e. enough for a 133-minute movie including several audio tracks in formats such as stereo, Dolby Digital or DTS, and advanced menu systems, subtitles and still pictures that can be played by many standalone DVD players and most computer DVD-ROMs. If the disc has two layers per side, then it can store up to 17GB of data. DVD uses MPEG-2 compression for video and audio.

E
EIB - European Installation Bus (a.k.a. Instabus). An embedded control protocol for digital communication between devices. It consists of a two-wire bus line that is installed along with normal electrical wiring. The Instabus functions like a telephone line over which appliances can be controlled, and links all appliances to a decentralised communication system.

F
FireWire - see IEEE-1394.

Front Projection - when a projector, usually ceiling-mounted, projects the picture onto a white screen. Both the projector and the screen may be retractable when not in use.

H
HDCP - High-bandwidth Digital Content Protection – encryption to prevent copying of the digital HDTV signal. The system works by inserting “locks” into the digital video signal. These “locks” are read by both the source device and the display to produce a “key”. Basically, if the key fits the locks, the image is displayed in High Definition correctly.

HDMI – High Definition Multimedia Interface – the new SCART, but the same size as a USB plug (used commonly for data transfer on PCs). HDMI offers the highest quality of digital video and audio connection. The connection allows uncompressed High Definition content from HD devices. It is fully HDCP compliant.

Home automation - the automatic control of systems such as heating, lighting, entertainment, security and communications by a single user interface. Operation might be by remote control, wall-mounted keypad and/or personal computer, and may be manual or programmed.

HVAC - Heating, Ventilation and Air-Conditioning.

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I
IEEE1394 - (a.k.a. FireWire or iLink). A communications protocol that allows direct digital transfer of data from one device to another. IEEE1394 allows for example, digital video from a DV camcorder to be transferred to the hard disk of a personal computer, provided both camera and computer have an IEEE1394 connection.

IR - Infra-red. IR frequencies have electromagnetic wavelengths that are shorter than those of RF fields. IR is typically used for sending wireless control signals from television and hi-fi remote-controllers, some cordless computer keyboards and mice, and some wireless hi-fi headphones.

K
Kbps - kilobits per second.
kBps - kilobytes per second. There 8 bits to a byte.

L
LCD - Liquid Crystal Display. A digital display that uses liquid crystal cells that change reflectivity in an applied electric field. LCDs are used for portable computer displays, watches and most recently, TV screens.

M
Macro - a sequence of commands that have been pre-programmed into a control device, and that can be activated by one touch. For example, when the user selects 'Showtime' on a home cinema touchscreen remote control, it could be programmed to dim the lights, draw the blinds, lower the projector screen, start up the DVD player, amplifier and projector and commence playback.

Mbps - megabits per second. 1Mb/s is 1024 times faster than 1kb/s.
MBps - megabytes per second.

MP3 - MPEG Layer 3. An encoded audio track, that uses 12 times less data than that of the same track recorded at standard CD quality. MP3 requires shorter download times if used to transfer music via the Internet for example, and less storage space. This has given rise to MP3 players such as the Apple iPod. Provided they have MP3 decoding capabilities, CD and DVD players can read a CD that has been burned with MP3 tracks.

MPEG-2 - is a video compression system that reduces the data required to show a video picture by a factor of around 40. MPEG-2 is used by DVD-Video, digital broadcast satellite, and digital TV (including HDTV).

MPEG-4 - sometimes called the 'MP3 of the video world', MPEG-4 is an encoding format designed for multimedia applications including web, handheld and wireless devices.

Multi-room - a term used to describe any distributed system, such as an audio or heating system, that covers a number of rooms in a building.

N
NVOD - Near Video On Demand. A system typically used for subscription movies such as Sky Movies, whereby the same movie is continuously played on several channels, with the start time between each channel being staggered by 15 or 30 minutes.

P
Plasma display – the first of the big screen, flat panel TV displays. Uses electricity to charge tiny gas pockets behind glass to generate colours. Many modern plasma screens now include TV and digital tuners to receive TV signals. Connected to a DVD player, especially using HDMI or component video connections, picture quality is stunning. This is the first step towards home cinema for many people.

PDA - Personal Digital Assistant – a handheld electronic diary, phone book and multimedia device. Many mobile telephones have limited PDA type functions.

PVR - Personal Video Recorder. A video recorder that records to hard disk, and usually supports both programmed recording as well as automated recording according to your personal profile. Sky+ is perhaps the best know PVR.

R
Regional Coding - a system used to prevent DVDs bought in one region of the world from being played in another. In practice, Regional Codes can often be side-stepped (hacked) by DVD players.

REN - Ringer Equivalency Number. The total number of phone equipment (such as telephone base units or answering machines) attached to a domestic network. This normally cannot exceed three, otherwise there may not be sufficient current to make the devices ring. The REN value is usually printed on the bottom of a unit, and in the unit's manual.

Router - A router connects a home network to external broadband networks or other computers. Works with an ethernet switch, which connects the computers and peripherals within the house and intelligently organizes the distribution of the information they exchange. Routers and hubs/switches are traditionally separate units, but are more frequently included in the same box, and sometimes a DSL modem also.

RF - Radio Frequency. Many types of wireless system, such as cordless and mobile phones, radio and television signals, and satellite communications, operate in the RF spectrum.

RF Modulator - a device which converts a video signal into a radio frequency signal for distribution through a TV (coaxial) network.

RJ-45 - the connector used with CAT5 and Ethernet cables. It looks like a telephone jack but has eight wires instead of four or six.

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S
Scene Lighting - where different lighting circuits are dimmed or activated to create a particular mood, such as a reading scene or movie-viewing scene.

Smart home - a dwelling, usually a new one, that is equipped with special structured wiring that allows occupants to control or program various automated home electronic devices using single commands.

Star/Radial Wiring - (a.k.a. Home Run). A wiring system whereby cables are distributed from a central hub location to each access point, allowing independent access to any of the signals or services from any point in the house.

Subwoofer - (a.k.a. sub). A loudspeaker that is specifically designed to handle bass in a home cinema system.

T
TFT - Thin Film Transistor. The highest quality and brightest LCD colour display type.

THX - Tomlinson Holman's eXperiment. An audio standard developed by Lucasfilm for equipment such as home cinema amplifiers, speakers and source equipment. Equipment is tested to meet the stringent specifications required for THX status.

Touchscreen - in the form of a touch-sensitive LCD, tends to be incorporated into remote controllers that allow the user to select different menus and controls.

U
UpnP - Universal Plug and Play. Developed by Microsoft, this is an open standard technology for transparently connecting appliances, PCs, and services, by extending Plug and Play to support networks and peer-to-peer discovery and configuration.

V
VC - Video Conferencing.
VCR - Video Cassette Recorder.

W
Wi-Fi - Wireless Fidelity. Wi-Fi is the popular term for a high-frequency wireless local area network (WLAN). It is specified in the IEEE 802.11b specification and is part of a series of wireless specifications together with 802.11, 802.11a, and 802.11g. When using a laptop, Wi-Fi is more convenient than a wired LAN. Unless adequately “locked down”, a Wi-Fi LAN can be susceptible to access from the outside by unauthorised users.

X
X-10 - a communications language that allows compatible products to talk to each other using the existing electrical wiring in the home. X10 signals use short RF bursts to represent digital information for communication between transmitters and receivers.

Z
Zone - a designated area of a building for the provision of any service. In a multi-room audio system, for example, each bedroom would typically constitute a separate zone.

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