Glossary | Business Communications

Network Cabling Support


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A fibre optic cable based version of an IEEE 802.3 network.


That portion of a 10Base-F network that defines the requirements for the fibre optic cable backbone network.


That portion of a 10Base-F network that defines the fibre optic cable link between a concentrator and a station.


IEEE 802.3 Ethernet LAN standard, with data on CAT 3 or Cat 5 twisted-pair (TP) wiring, with a data rate of Mbps.

100Base T

IEEE 802.3 Ethernet LAN standard, with data on CAT 5 twisted-pair wiring, with data rate of 100 Mbps.


A thin coaxial cable version of an IEEE 802.3 network.


A thick coaxial cable version of an IEEE 802.3 network; very similar to the original Ethernet specification.

8B/10B encoding

A signal modulation scheme in which either 4 bits are encoded into a 5-bit word or 8 bits are encoded into a 10-bit word.

802.3 network

Commonly known as Ethernet. A 10 MBPS CSMA/CD bus based LAN

802.5 network

A token passing ring network operating at 4 or 16 MBPS.


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Alternating Current. All electrical outlets in a home operate at 120V, 60Hz.


Automatic Call Distribution. Based on modern digital PABX systems, ACD software manages the rules upon which inbound business telephone calls, to a helpdesk for example, are distributed amongst the available support staff in order to improve the quality of service to customers. Large systems are often referred to as Call Centres.


An active electronic device to increase the amplitude of a signal.


An analogue signal is a waved-shaped signal that represents information in a continuously variable and directly measurable physical quantity, such as voltage. Still largely used for the local connection of telephone services, despite the conversion of the main telephone backbone networks to digital transmission. Analogue lines are the local loop bearers for Broadband digital services, such as ADSL and VDSL.


Asynchronous Transfer Mode. A broadband technology that will allow varying bandwidth to be switched at very high speeds, allowing the delivery of multiple data streams, carrying for example voice, data and video information, on a single connection.


American Wire Gauge. AWG is the standard gauge for measuring the diameter of copper, aluminium and other conductors.


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Transfer capacity of a network link. Such as; a FAX machine transfers data at 14,400 bits per second, an analogue modem at 34,400 bits per second (33.6kbps), ISDN at 65,536 bits per second (64Kbps) and VDSL at (up to) 104,857,600 bits per second (100Mbps).


A network that supports high-speed data transmission. Unlike broadband systems, a baseband network uses the whole of its bandwidth to transmit a single digital signal: multiple simultaneous transmissions are therefore not possible.

Baseband Video

Raw video signal video source (e.g. camera or VCR). Typically appears at a yellow phone jack labelled 'Video'.


A device that connects two separate networks - usually LANs - allowing them to exchange traffic as if they were a single network.


A network that supports a number of simultaneous transmissions over a single physical link. Broadband is often used to describe ADSL and VDSL services.

Broadband Video

Modulated video signal. Usually comes from an antenna or CATV feed and contains many channels. Also applies to output of modulators. Typically carried on coax cable and connects to F-connector labelled 'CATV/Antenna'.


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Cat 5 & Cat 5e

Category 5 are performance class for cables, jumper cables, jacks, connectors and interconnection components. Cable specification used for connection of computers to switches in an Ethernet LAN with RJ45 type connectors. This cable type can also be used for digital voice distribution and is the primary cable type for structured wiring systems. NOTE that only the Cat 5E cable specification will support 1000BaseT (Gigabit Ethernet). The performance level and testing is specified in the EIS/TIA 568A commercial wiring standard.

Cat 6

Category 6. A more stringent cable specification than Cat5E which provides support for 10GBaseT (10 Gigabit Ethernet), albeit with a reduced length limit of 55 metres. The more recent Cat6A specification supports 10GBaseT up to 100 metres.


Closed Circuit Television, such as a security or safety camera.


Calling Line Identification. An electronic identifier transmitted in the call signal that identifies the number of the telephone making the call.

Co-Axial cable

A single cored copper cable with a braided earth screen, as used in television distribution. The centre conductor is surrounded by a dielectric, a shield and an outer insulator. If the signal is unbalanced, and the shield provides noise immunity.


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Information that is encoded in a series of “1”s and “0”s.


Digital Broadcast Satellite.

Decibel (dB)

A logarithmic ratio used to indicate signal strength.


This describe a signal represented by two digits - usually 0 or 1 - during transmission; commonly contrasted with an analogue signal, whose value varies continuously. Digital transmission methods transport a computer's binary (two value) language, removing the need for a modem to translate between them. The benefits of digital transmission include high bandwidth and almost error-free communications.

Domain Name

A logical grouping, used to organise networked computers. On the Internet, the highest-level domain is the country; sub-domains, listed to the left and separated by dots, work through an increasingly specific hierarchy in order to identify a unique location, known as the 'domain name'. Reading from right to left is analogous to reading from the bottom to the top line of a postal address. Business Communication's domain name is


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Electronic Data Interchange. The secure electronic exchange of contractual documentation, such as Purchase Orders or Invoices. Heavily used in the retail and automotive sectors.


Ethernet in the First Mile. A service providing Ethernet access across voice quality copper cable. As with all copper based service, achievable speed depends on distance and cable quality but maximum generally offered in the UK is 35 Mbps using 4 copper pairs.


Known as Electronic Mail. Messages, usually text, sent from one person to another, or from one person to many, via a computer. The recipient does not need to be physically present or connected to the network at the time of transmission.


A scheme to represent digital ones and zeros through combining high and low voltage states.


Supports data transmission at speeds of 10 Mbit/s (10baseT), 100 Mbit/s (100baseT) or 1000Mbit/s (1000baseT or Gigabit); widely used to connect computers on a LAN. Connections between PC’s are usually by Unshielded Twisted Pair (UTP) cable with RJ45 connectors which requires an additional piece of hardware called a Switch through which all the machines are connected.


An Intranet which provides access to a community of users such as a company and its major suppliers.


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Fibre optics

Light transmission through optical fibres for communication or signalling.


Fibre To The Cabinet. Because the speed of any DSL service is limited by the length of copper cable between the exchange and customer premises, FTTC technology is prefered as it uses high speed fibre cable to connect to local street cabinets and VDSL across the remaining, relatively short, link to the customer premises. Speeds of 'up to' 80 Mbps can be achieved


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Giga Bits Per Second. 1 Billion Bits Per Second.


Giga Hertz. 1 Billion Hz.


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Hardware used to interconnect computers in older LAN systems, such as 10baseT or 100baseT Ethernet. Largely replaced by switches in modern networks.


Heating, Ventilation, and Air Conditioning.


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Insertion Loss

The loss of signal die to attenuation or power splitting through a passive device.


Offering similar facilities to the Internet, an intranet is distinguished by the restriction of access to a closed group of users - for example, within the same company.


PBX based on IP technology, often Linux server based.


Infrared, commonly used by remote controls.


Integrated Services Digital Network. Can be used for voice and data applications simultaneously and offers extremely cost-effective solutions to any size of business / operation.


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The female connector, usually mounted in a faceplate or on equipment. Accepts a plug.

Jumper Cord

A short, connectorised cable, which interconnects two jacks, e.g. from equipment to a wall plate.


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Kilo Hertz. 1,000 Hz.


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Local Area Network. Often referred to as a data communications network for premises. A network linking together computers, printers and related devices, usually over a short distance (less than 1 km) and normally within a single building or site. A LAN allows all users on the network to share resources, optimising efficiency and avoiding unnecessary duplication of assets or effort. Separate from the public network, a LAN can support high transmission speeds - typically between 100 Mbit/s and 1000 Mbit/s.


Light Emitting Diode.


A cable with connectors attached to a transmitter (source) and receiver (detector).


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Megabits (millions of bits) Per Second.


Mega Hertz, 1 million Hz.


Acronym for 'Modulator-Demodulator'. A device that carries out both modulation and demodulation.




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Network Interface Unit (or NID: Network Interface Device). A small box, usually mounted on the outside wall a building, which is the boundary between the phone provider wiring and the building wiring.


National Electrical Code. Defines building flammability requirements for indoor cables.


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Open Standard Interconnect

A 7-layer model defined by ISO for defining a data communication network. It provides means for executing the blue print of the network architecture.

Optical fibre

Synonym for fibre optic cable. Cable made of glass fibres through which signals are transmitted as pulses of light. Fibre cables are capable of carrying very high bandwidth and are used extensively for long distance interconnections in the public telephone network. Optical fibre cable is increasingly being used for interconnection of LAN’s between buildings and for backbone links within buildings.


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Private (Automatic) Branch Exchange.

Patch Panel

Distribution area to rearrange cable connections and circuits.


A male connector, usually on a cable. Plugs into a jack.


Plain Old Telephone Service. Also referred to as 'analogue' telephone service. Includes voice, fax, and modem.


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Made from 4 different elements.


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Rayleigh scattering

The scattering of light that results from small in homogeneities in material density or composition. This causes losses in optical power.


Rhodamine B dopant.


It is an electronic package, which converts optical signals to electrical signals.

Receiver sensitivity

The minimum acceptable value of average received power at the fibre optic cable receiver point. In the case of digital signals the optical power is usually quoted in Watts or dBm.


Light that is reflected back along the path of transmission, from either the coupling region, the connector or the terminated fibre optic cable. Also known as 'Return loss'.


The abrupt change in direction of light as it travels from one material to a dissimilar material. Some of the reflected power gets transmitted back to the source.


The bending of a beam of light at an interface between two dissimilar media.

Refractive Index

The ratio of the velocity of light in a vacuum to its velocity in the medium. It is a synonym of index of refraction. Its symbol in ‘n.’


A repeater designed for digital transmission that both amplifies and reshapes the signal. Also referred to as Regenerative repeater.


An optoelectronic device that amplifies or boosts a signal. Basically, it returns a signal to its original strength.

Return reflection

Reflected optical energy that propagates backward to the source in a fibre optic cable.

Ring network

A network topology in which terminals are connected in a point to point serial fashion in an unbroken circular configuration.


Application for indoor cables that pass between floors. It is normally a vertical shaft or space.


A device (or computer/software package) that interconnects LANs, ensuring that traffic is carried over the best available path to its intended destination. Unlike a bridge, a router must be compatible with the protocols used by the networks that it connects - the more advanced systems can understand different protocols and link disparate LAN’s.




Signalling code.


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A connector type. It is primarily used with single-mode fibre optic cables. It offers low cost, simplicity and durability.

Scattering – A property of glass which causes light to deflect from the fibre optic cable and contributes to losses.


Space Domain Multiplexing

Semiconductor Laser

Same as a laser diode.


For a fibre optic cable receiver, it is the minimum optical power required to achieve a specified level of performance.

Shot noise

Noise caused by random current fluctuations arising from the discrete nature of electrons.

Signal to noise ratio

The ratio of signal power to noise power.


Glass material, nearly pure SiO2.


Step index plastic fibre optic cable.


Transmission in only 1 direction.

Simplex cable

A term sometimes used for a single-fibre cable.


A small core, fibre optic cable that supports only 1 mode of light propagation above the cut-off wavelength.


Session Initiation Protocol. SIP is an IP protocol used to initiate different multimedia communications i.e. Voice, Video and Video conference calls over IP.


Signal to noise ratio. Usually expressed in dB.


An optical pulse that does not suffer dispersion as it propagates over a distance.


Synchronous Optical Network. An international standard for fibre optic cable based telephony.


Within the context of fibre optics, it is a light emitter, either an LED or laser diode, for a fibre optic cable based link.


The permanent joining of fibre optic cable ends to identical or similar fibre optic cables without using a connector.


A keyed bayonet connector type similar to a BNC connector. It is used for both multi-mode and single-mode fibre optic cables. There are 2 versions ST and ST-II.

Star coupler

A coupler for a fibre optic cable in which power at any input port is distributed to all output ports.

Star network

A network in which all terminals is connected through a single point, such as a star coupler.

Steady state

Equilibrium mode distribution.


Removing the coating from a fibre optic cable.

Structured Cabling

A methodology for the design, implementation and management of cable distribution systems for voice and data services. Based upon international standards, such as EN50173 Cat5, structured wiring systems tend to be more expensive to install initially but pay massive dividends over time in terms of ease of change and management of connectivity, even for small installations.


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Designation for the pin assignments in a modular jack. Most appropriate for use in the residence.

TP - Twisted Pair Wire

A twisted pair consist of two insulated copper wires twisted together. Cat 5 cable is 4 twisted pairs in a common sheath. The twisted provide balance and noise immunity. Generally used for analogue voice and digital data (LAN) transmission.

Tap loss

In a fibre optic cable, coupler is the ratio of power at the tap port to the power at the input port.

Tap port

In a fibre optic cable coupler in which the splitting ratio between output ports is not equal it is the output port containing the lesser power.


Transmission Control Protocol/Internet Protocol. The suite of protocols originally developed for the ARPANetTM and now used to define membership of its successor, the Internet. TCP/IP specifies how data is sent and received over a network - how it should be routed and addressed.


Time Division Multiplexing.
This is where low speed channels share a given transmission medium, i.e. a fibre optic cable. With this technique they share it on a time basis. Each channel is given specific time slots to transmit during and can only transmit during these time slots.

Tee coupler

A 3 port optical coupler.


Made from 3 different elements.

Thermal noise

Noise resulting from thermally induced random fluctuation in current in the receiver’s load resistance.

Thermal stability

A measure of the insertion loss variation as the device undergoes various environmental changes.

Throughput loss

In a fibre optic cable coupler, it is the ratio of power at the throughput port to power at the input port.

Tight buffer

Type of cable construction whereby each glass fibre optic cable is tightly buffered by a protective thermoplastic coating.

Token ring

A ring based networking scheme. A token is used to control access to the network. Used by IEEE 802.5 and FDDI.

Total bandwidth

The combined modal and chromatic bandwidth.

Total internal reflection

Total reflection of light back into a material when it strikes the interface of a material having a lower index at an angle below the critical angle.


A device for converting energy from one form to another, such as optical energy to electrical energy.


A combination of transmitter and receiver providing both output and input interfaces with a device.

Transmission loss

Total loss encountered in transmission through a system.


In the context of a fibre optic cable based communication link an electrical package, which converts an electrical signal to an optical signal.

Tree coupler

A passive fibre optical component in which power from 1-input is distributed to more than 2-output fibre optic cables.




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Unshielded twisted pair. A type of cabling which is used for the interconnection of computers and switches in an Ethernet LAN as well as the distribution of digital voice systems, such as ISDN2. UTP is the standard cable type for Category 5 & 5E structured cable systems.


The maximum insertion loss difference between ports of a coupler.




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Vertical cavity semiconductor laser.


Very-High-Bit-Rate Digital Subscriber Link. A DSL technology which provides data rates up to 52 Mbps (VDSL1) or 100+ Mbps (VDSL2). In the UK, VDSL is used to provide the final part of the FTTC service, using copper pairs to link from the DSLAM to the customers premises.

Velocity of light

The velocity of light is 300,000 km/sec in a vacuum. In a medium it depends in the refractive index and the wavelength.


Voice over IP. A methodology for the transmission of voice signals using an IP network.


Virtual Private Network. A methodology for linking LANs together across a public network, such as the Internet.


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Wide Area Network. A network of connected computers that cover a great geographical area.


A 2 dimensional substrate which carries light in channels inscribed in the material.


Wavelength Division Multiplexing.
Simultaneous transmission of several optical signals of different wavelengths on the same fibre optic cable.


Wavelength Independent Coupler.


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