Air Blown Fiber (ABF):  Small, flexible plastic microduct tubing installed prior to the installation of individual or multiple optical fibers that are blown in through the microduct using compressed air.

Asynchronous Transfer Mode (ATM):  Technology selected by the International Telecommunications Union (ITU, formerly CCITT) for broadband ISDN. This communications protocol is also specified by the ATM Forum (Foster City, CA) for 155 Mb/s transmission over twisted-pair cable and various bit rate optical fiber cabling applications.

Attenuation:  A reduction in power or amplitude of the transmitted signal. In cables, it is generally expressed in decibels per unit length.

Attenuation to Crosstalk Ratio (ACR):  The difference between attenuation and crosstalk measured in decibels.

Auxiliary Disconnect Outlet (ADO):  A device usually located within the tenant or living unit used to terminate the ADO cable or backbone cable.

Auxiliary Disconnect Outlet (ADO) Cable:  In residential applications, the cable from the auxiliary telecommunications disconnect outlet/connector or the distribution device in a customer's premises to the backbone facility or the point of demarcation.

Backbone Cabling:  Cable and connecting hardware that comprise the main and intermediate cross-connects, as well as cable runs that extend between telecommunications rooms, equipment rooms and entrance facilities.

Balance:  An indication of signal voltage equality and phase polarity on a conductor pair. Perfect balance occurs when the signals across a twisted-pair are equal in magnitude and opposite in phase with respect to ground.

Balanced Signal Transmission:  Two voltages, equal and opposite in phase with respect to each other, across the conductors of a twisted-pair (commonly referred to as tip and ring).

Balun:  An impedance matching transformer used to convert unbalanced coaxial signals to balanced signals.

Bandwidth:  A range of frequencies, usually the difference between the upper and lower limits of the range, typically expressed in megahertz (MHz). It is used to describe the information-carrying capacity of a medium. In copper and optical fibers, the bandwidth decreases with increasing length. Optical fiber bandwidth is specified in megahertz kilometers (MHz-km).

Bonding :  The permanent joining of metallic parts to form an electrically conductive path that will assure electrical continuity and the capacity to conduct safely any current likely to be imposed on it.

Break Test Access:  Method of disconnecting a circuit that has been electrically bridged to allow testing on either side of the circuit without disturbing cable terminations. Devices that provide break test access include: disconnect blocks, bridge clips, plug-on protection modules, and plug-on patching devices.

Bridged Tap:  The multiple appearances of the same cable pair or fiber at several distribution points. Also known as parallel connections.

Bridging:  A means of providing through connections between conductors or pairs that are terminated on connecting blocks. These through connections are commonly provided by means of individual metallic bridging clips or multiple bridging clips that are housed in a plastic insulator.

Building Distributor (BD):  The international term for intermediate cross-connect. A distributor in which the building backbone cable(s) terminates and at which connections to the campus backbone cable(s) may be made.

Bundled Cable:  An assembly of two or more cables continuously bound together to form a single unit prior to installation (sometimes referred to as loomed, speed-wrap or whip cable constructions).

Bus Topology:  A linear configuration where all network devices are placed on a single length of cable. It requires one backbone cable to which all network devices are connected.

Cabling:  A combination of cables, wire, cords and connecting hardware used in the telecommunications infrastructure.

Campus Backbone:  Cabling between buildings that share telecommunications facilities.

Campus Distributor (CD):  The international term for main cross-connect. The distributor from which the campus backbone cable emanates.

Category (1):  ANSI/TIA/EIA-568-B series of documents, the North American standards for cabling describes mechanical properties and transmission characteristics of unshielded twisted-pair (UTP) cables and screened twisted-pair (ScTP) cables and assigns a unique number classification (category 3, category 5e, and category 6).

Category (2):  ISO/IEC IS 11801 2nd edition, the international standard for cabling and local standardization documents define cabling component categories based on transmission performance parameters such as attenuation and NEXT loss, over a specified frequency range. Component categories category 5, category 6 and category 7.

Channel:  The end-to-end transmission path connecting any two points at which application specific equipment is connected. Equipment and work area cables are included in the channel.

Classification:  Application classes for cabling have been identified for the purpose of the ISO/IEC 11801 standard;
  • Class A: cabling is characterized up to 100 kHz
  • Class B: cabling is characterized up to 1 MHz
  • Class C: cabling is characterized up to 16 MHz
  • Class D: cabling is characterized up to 100 MHz
  • Class E: cabling is characterized up to 250 MHz
  • Class F: cabling is characterized up to 600 MHz
  • Optical Class: optical fiber links are characterized from 10 MHz and above.
Collapsed Backbone:  A centralized network contained in one device. The network is said to be collapsed and made to fit into a box. Individual networks are connected to this central device and can then communicate with one another.

Common Mode Transmission:  A transmission scheme where voltages appear equal in magnitude and phase across a conductor pair with respect to ground. May also be referred to as longitudinal mode.

Consolidation Point (CP):  A location for interconnection between horizontal cables that extend from building pathways and horizontal cables that extend into work area pathways.

Cross-connect:  A facility enabling the termination of cables as well as their interconnection or cross-connection with other cabling or equipment. Also known as a distributor.

Cross-connection:  A connection scheme between cabling runs, subsystems and equipment using patch cords or jumpers that attach to connecting hardware on each end.

Crosstalk:  Noise or interference caused by electromagnetic coupling from one signal path to another. Crosstalk performance is generally expressed in decibels.

Decibel (dB):  A standard unit for expressing transmission gain or loss as derived from a ratio of signal voltages or power.

Delay Skew :  The difference in propagation delay between the fastest and slowest pair in a cable or cabling system.

Demarcation Point (DP):  A point at which two services may interface and identify the division of responsibility.

Differential Mode Transmission:  A transmission scheme where voltages appear equal in magnitude and opposite in phase across a twisted-pair with respect to ground. May also be referred to as balanced mode.

Distributor:  The term used for the functions of a collection of components (e.g. patch panels, patch-cords) used to interconnect cables.

Ducting:  See Pathway.

Electromagnetic Compatibility (EMC):  The ability of a system to minimize radiated emissions and maximize immunity from external noise sources.

Electromagnetic Interference (EMI):  The interference in signal transmission or reception caused by the radiation of electrical and magnetic fields.

Electronic Industries Alliance (EIA):  An organization that sets standards for interfaces to ensure compatibility between data communications equipment and data terminal equipment.

Electronic Industries Association:  A standards organization that specializes in the electrical and functional characteristics of interface equipment. The organization sets standards for interfaces to ensure compatibility between data communications equipment and data terminal equipment.

Entrance Facility (EF):  An entrance to a building for both public and private network service cables (including antennae), including the entrance point at the building wall and continuing to the entrance room or space. Entrance facilities are often used to house electrical protection equipment and connecting hardware for the transition between outdoor and indoor cable.

Entrance Facility, Telecommunications:  An entrance to a building for both public and private network service cables (including antennae) beginning with the entrance point at the building wall and continuing to the entrance room or space.

Entrance Point, Telecommunications:  The point of emergence of telecommunications conductors through an exterior wall, a concrete floor slab, or from a rigid metal conduit or intermediate metal conduit

Equal Level Far-end Crosstalk (ELFEXT):  Crosstalk measured at the opposite end from which the disturbing signal is transmitted, normalized by the attenuation contribution of the cable or cabling.

Equipment Cable:  A cable or cable assembly used to connect telecommunications equipment to horizontal or backbone cabling.

Equipment Room (ER):  A centralized space for telecommunications equipment that serves the occupants of the building or multiple buildings in a campus environment. An equipment room is considered distinct from a telecommunications room because it is considered to be a building or campus serving (as opposed to floor serving) facility and because of the nature or complexity of the equipment that it contains.

Equipment Room, Telecommunications:  A centralized space for telecommunications equipment that serves the occupants of the building. An equipment room is considered distinct from the telecommunications room because of the nature and complexity of the equipment it houses.

FC Connector:  A type of optical fiber connector identifiable by its round, screw-operated locking nut. It is usually metal. Its ruggedness leads it to be widely used in test equipment

Far-end Crosstalk (FEXT):  Crosstalk measured at the opposite end from which the disturbing signal is transmitted.

Fiber Distributed Data Interface (FDDI):  Operates at 100 megabits per second (Mb/s). Developed by the ANSI X3T9.5 committee. This is a token-passing, dual-ring architecture that provides redundancy using fiber optic cable with transmission up to 2 kilometers.

Fiber Optic Transmission:  A communications scheme whereby electrical data is converted to light energy and transmitted through optical fibers.

Firestop:  A material, device, or assembly of parts installed in a cable pathway at a fire-rated wall or floor to prevent passage of flame, smoke or gases through the rated barrier (e.g., between cubicles or separated rooms or spaces).

Floor Distributor (FD):  The international term for horizontal cross-connect. The distributor used to connect between the horizontal cable and other cabling subsystems or equipment.

Ground:  A conducting connection, whether intentional or accidental, between an electrical circuit (telecommunications) or equipment and earth, or to some conducting body that serves in place of the earth.

Hertz (Hz):  A measure of frequency as defined in units of cycles per second.

Home-run Cabling:  A distribution method in which individual cables are run directly from the horizontal cross-connect to each telecommunications outlet. This configuration is also known as star topology.

Horizontal Cabling:  The cabling between and including the telecommunications outlet and the horizontal cross-connect.

Horizontal Cross-connect (HC):  A cross-connect of horizontal cabling to other cabling, e.g., horizontal, backbone, or equipment.

Hub:  Equipment that serves as the centralized connection point for a network or portion thereof. Hubs are used for multiplexing, multi-port bridging functions, switching and test access. They can be either passive or active and are not considered to be part of the cabling infrastructure.

Hybrid cable:  An assembly of two or more cables, of the same or different types or categories, covered by one overall sheath.

Insertion loss (1):  The loss resulting from the insertion of a device in a transmission line, expressed as the reciprocal of the ratio of the signal power delivered to that part of the line following the device to the signal power delivered to that same part before insertion.

Insertion loss (2):  In an optical fiber system, the loss of optical power caused by inserting a component, such as a connector, coupler or splice, into a previously continuous optical path.

Insulation Displacement Connection (IDC):  A wire connection device that penetrates the insulation of a copper wire when it is being inserted (punched-down) into a metal contact, allowing the electrical connection to be made.

Intelligent Hub:  A hub that performs bridging and routing functions in a collapsed backbone environment.

Interbuilding Backbone :  Telecommunications cable(s) that are part of the campus subsystem that connect one building to another.

Interconnection:  A connection scheme that provides direct access to the cabling infrastructure and the ability to make cabling system changes using equipment cords.

Intermediate Cross-Connect (IC):  The connection point between a backbone cable that extends from the main cross-connect (first-level backbone) and the backbone cable from the horizontal cross-connect (second-level backbone).

Intermediate Distribution Frame (IDF):  In a central office or customer premises, a frame that (a) cross connects the user cable media to individual user line circuits and (b) may serve as a distribution point for multipair cables from the main distribution frame (MDF) to individual cables connected to equipment in areas remote from these frames.

Intrabuilding Backbone:  Telecommunications cable(s) that are part of the building subsystem that connect one equipment room to another.

Jumper Wire:  An assembly of twisted-pairs without connectors on either end used to join telecommunications links at a cross-connect.

Link:  An end-to-end transmission path provided by the cabling infrastructure. Cabling links include all cables and connecting hardware that comprise the horizontal or backbone subsystems. Equipment and work area cables are not included as part of a link.

Local Area Network (LAN):  A geographically limited data communications system for a specific user group consisting of a group of interconnected computers, sharing applications, data and peripheral devices such as printers and CD-ROM drives intended for the local transport of data, video, and voice.

Local Exchange Carrier (LEC):  The local regulated provider of public switched telecommunications services.

Longitudinal Conversion Loss (LCL):  A measure (in dB) of the differential voltage induced on a conductor pair as a result of subjecting that pair to longitudinal voltage. LCL is considered to be a measure of circuit balance.

MAU (1):  Multi-station Access Unit in reference to Token Ring.

MAU (2):  Medium Attachment Unit in reference to Ethernet A wiring concentrator used in Local Area Networks. A device that allows terminals, PCs, printers, and other devices to be connected in a star-based configuration to Token Ring or Ethernet LANs. MAU hardware can be either active or passive and is not considered to be part of the cabling infrastructure.

Main Cross-connect (MC):  A cross-connect for first level backbone cables, entrance cables, and equipment cables.

Modular Jack:  A telecommunications outlet/connector for wire or cords as defined in the FCC Part 68 Subpart F. Modular jacks can have 4, 6 or 8 contact positions, but not all the positions need be equipped with contacts.

Modular Plug:  A telecommunications connector for wire or cords as defined in the FCC Part 68 Subpart F. Modular plugs can have 4, 6 or 8 contact positions, but not all the positions need be equipped with contacts.

Multi-user Telecommunications Outlet Assembly (MuTOA):  A grouping in one location of several telecommunications/outlet connectors.

Multimedia (1):  An application that communicates to more than one of the human sensory receptors.

Multimedia (2):  Applications that communicate information by more than one means or cabling media.

Multimode Optical Fiber:  An optical fiber that will allow many bound modes to propagate. The fiber may be either a graded-index or step-index fiber. Multimode optical fibers have a much larger core than singlemode fibers. See also Optical Fiber Cable.

Nanosecond (ns):  One billionth of a second (10-9 seconds).

Near-end Crosstalk (NEXT Loss) :  The undesired coupling of a signal from one pair of wires to another. Signal distortion as a result of signal coupling from one pair to another at various frequencies.

Network Demarcation Point :  The point of interconnection between the local exchange carrier's telecommunication facilities and the telecommunications systems wiring and equipment as the end user's facility. This point shall be located on the subscriber side of the telephone company's protector or the equivalent thereof in cases where a protector is not required.

Open Office Cabling:  The cabling that distributes from the telecommunications closet to the open office area utilizing a consolidation point or multi-user telecommunications outlet assembly.

Outlet, Telecommunications :  A fixed connecting device where the horizontal cable terminates. The telecommunications outlet provides the interface to the work area cabling. Sometimes referred to as a telecommunications outlet/connector.

Outlet/Connector, Telecommunications:  A connecting device in the work area on which horizontal cable terminates.

Patch Cord:  A length of cable with connectors on one or both ends used to join telecommunications links at a cross-connect.

Patch Panel:  Connecting hardware that typically provides means to connect horizontal or backbone cables to an arrangement of fixed connectors that may be accessed using patch cords or equipment cords to form cross-connections or interconnections.

Pathway:  A facility (i.e., conduit) for the placement and protection of telecommunications cables. Same as raceway or ducting.

Plenum:  A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system.

Private Branch Exchange (PBX):  A private switching system usually serving an organization, such as a business, located on the customer's premises. It switches calls both inside a building or premises and outside to the telephone network, and can sometimes provide access to a computer from a data terminal.

Propagation Delay:  The amount of time that passes between when a signal is transmitted and when it is received at the opposite end of a cable or cabling.

Punch Down:  A method for securing wire to a quick clip in which the insulated wire is placed in the terminal groove and pushed down with a special tool. As the wire is seated, the terminal displaces the wire insulation to make an electrical connection. The punch down operation may also trim the wire as it terminates. Also called cut down.

Quick Clip:  An electrical contact used to provide an insulation displacement connection to telecommunications cables.

Raceway:  See Pathway.

Return Loss:  Noise or interference caused by impedance discontinuities along the transmission line at various frequencies. Return loss is expressed in decibels.

Ring Conductor:  A telephony term used to describe one of the two conductors in a cable pair used to provide telephone service. This term was originally coined from its position as the second (ring) conductor of a tip-ring-sleeve switchboard plug.

Screened twisted-pair (ScTP):  A balanced twisted-pair cable surrounded by metallic braid, foil (screen) or both and bound in a single cable sheath.

Shielded twisted-pair (SSTP):  A cable surrounded by a metallic braid, foil or both and bound in a single plastic sheath containing balanced twisted-pair conductors that are individually shielded.

Singlemode Optical Fiber:  An optical fiber that will allow only one mode to propagate; this fiber is typically a step-index fiber.

Small Form Factor:  An optical fiber connector and adapter that provide for two strands of fiber in a surface area similar to an unshielded twisted-pair (RJ-style) plug and socket.

Sneak Current:  A low-level current that is of insufficient strength to trigger electrical surge protectors and, therefore, is able to pass through them undetected. These currents may result from contact between communications lines and AC power circuits or from power induction, and may cause equipment damage unless secondary protection is used.

Star Topology (1):  A method of cabling each telecommunications outlet/connector directly to a cross-connect in a horizontal cabling subsystem

Star Topology (2):  A method of cabling each cross-connect (HC and IC) to the main cross-connect (MC) in a backbone cabling subsystem.

Surge:  A rapid rise in current or voltage, usually followed by a fall back to a normal level. Also referred to as transient.

Telecommunications:  Any transmission, emission or reception of signs, signals, writings, images, sounds or information of any nature by cable, radio, visual, optical or other electromagnetic systems.

Telecommunications Industry Association (TIA):  An organization that sets standards for cabling, pathways, spaces, grounding, bonding, administration, field testing and other aspects of the telecommunications industry.

Telecommunications Room (TR):  An enclosed space for housing telecommunications equipment, cable terminations and cross-connect cabling used to serve work areas located on the same floor. The telecommunications closet is the typical location of the horizontal cross-connect and is considered distinct from an equipment room because it is considered to be a floor serving (as opposed to building or campus serving) facility.

Tip Conductor:  A telephony term used to describe the conductor of a pair that is grounded at the central office when the line is idle. This term was originally coined from its position as the first (tip) conductor of a tip-ring-sleeve switchboard plug.

Topology:  The physical or logical layout of links and nodes in a network. These include star, ring and bus configurations.

Transfer Impedance:  A measure (in W) of shield effectiveness.

Transition Point (TP):  A location in the horizontal cabling subsystem where flat under carpet cabling connects to round cabling.

Trunk:  A communication line between two switching systems. The term switching systems typically includes equipment in a central office (the telephone company) and PBXs. A tie trunk connects PBXs. Central office trunks connect a PBX to the switching system at the central office.

Twisted-Pair Distributed Data Interface (TP-DDI):  Trademark of 3COM Corporation. (See Twisted-pair Physical Media Dependent.)

Twisted-Pair Physical Media Dependent (TP-PMD):  Technology under review by the ANSI X3T9.5 working group that allows 100 Mb/s transmission over twisted-pair cable. Also referred to as CDDI or TPDDI.

Unshielded Twisted-Pair (UTP):  A cable with multiple pairs of twisted insulated copper conductors bound in a single sheath.

Webbed Conductors :  The manufacturing process that physically binds the conductor insulation of the wire pairs of an unshielded twisted-pair cable.

Work Area:  The area where horizontal cabling is connected to the work area equipment by means of a telecommunication outlet. A station/desk which is served by a telecommunications outlet. Sometimes referred to as a work station.

Work Area Cable:  A cable assembly used to connect equipment to the telecommunications outlet in the work area. Work area cables are considered to be outside the scope of cabling standards.
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