Abrasion Resistance
Ability to resist surface wear.
Absorption
Loss of power in an optical fiber, resulting from conversion of optical power into heat and caused principally by impurities, such as transition metals and hydroxyl ions, and also by exposure to nuclear radiation.
AC
alternating current
Accelerated Aging
A test that simulates long-time environmental conditions in a relatively short time.
Acceptance Angle
The biggest possible angle between a ray and the center axis
Access Method
Set of rules by which networks arbitrate their use.
Active/Passive Device
A device, such as a Token Ring multistation access unit (MAU), that supplies current for the loop that is considered active. One that does not supply current is considered passive.
ACE
above ground cable enclosure
Adapter
The adapter is the hardware device that connects two dissimilar devices. Example: a synchronous data link control (SDLC) adapter connects a gateway PC to a modem for SDLC communications.
Address
A unique identifier assigned to networks and stations so each device can be separately designated to receive and reply to messages.
Adjunct Power
Power supplied to optional data or voice equipment in an equipment room, telecommunications closet, or work area, through separate power supplies.
Adjusted Main Ring Length (AMRL)
The equivalent electrical main ring length (EEMRL) minus the length of the shortest intercloset cabling path.
Administration Point
A central location at which communication circuits are administered; that is, rearranged or rerouted by means of cross-connections or interconnections to information outlets.
Administration Subsystem
The part of a cabling distribution system that includes the connecting hardware components where you can add or rearrange circuits. These components include cross-connects and interconnects, and their associated patch cords or jumper wire. See Administration Point.
Aerial Cable
Telecommunications cable installed on supporting structures such as poles, bridge hangers, building extension supports, etc. These cables are typically non-filled cables intended exclusively for aerial placement via a separate metallic “strand” cable, or with support strand embedded in the same outer sheath (figure 8 cable).
Aerial Distribution Method
The method of running cable between buildings in campus systems by going through the air; that is, building to pole, pole to pole, and/or building to building.
AF
audio frequency
AGX
above ground fiber cross-connect system
AIA
American Institute of Architects
Air Handling Plenum
A designated area, closed or open, used for environmental air circulation (return air).
Alarm Indicator
A device, or combination of devices, such as bells, lamps, horns, gongs or buzzers that respond to a signal from an alarm sensor (FED-std-1037A).
ALPETH
Aluminum-polyethylene, the primary sheath for aerial cable.
ALVYN
Aluminum-polyvinyl-chloride, the preferred sheath for riser back-bone cable where a flame-retardant sheath is required to meet National Electrical Code (NEC) standards.
AM
amplitude modulation
Ambient
Conditions existing at a test or operating location prior to energizing equipment (e.g.: ambient temperature).
American National Standards Institute (ANSI)
Organization responsible for the definition and maintenance of standards. ANSI is the principal group in the United States for defining relative standards. ANSI represents the United States in the International Standards Organization (ISO).
American Standard Code for Information Interchange (ASCII)
A 7-bit binary code standardized by American National Standards Institute (ANSI) for use by personal computers (PCs) and some mainframes to represent alphanumeric and graphical characters. An additional bit is included to form an 8-bit character (byte).
Ampere (A)
A standard unit of current. One ampere (1 A) of current is produced by one coulomb (1 C) of charge passing a reference point in one second (1 sec).
Amplifier
An electronic component used to increase the strength of a transmitted analog signal. Performance is measured in decibels (dB). Similar to a repeater in digital systems.
Amplitude
The relative value of a varying wave form.
Amplitude Modulation
One of three basic methods (see Frequency and Phase Modulation) of adding information to a sine wave signal in which the magnitude of the signal is varied to transmit information.
Analog
A format that uses continuous physical variables such as voltage amplitude or frequency variations to transmit and receive information.
Analog Signal
A nominally continuous electrical signal that varies in amplitude or frequency in response to changes in the physical quantity (such as sound) that it represents.
Annealing
A process of controlled heating followed by gradual cooling to relieve mechanical stresses. Annealing copper makes it more pliable.
APD
avalanche photo diode
API
Application program interface gives users the ability to write programs that communicate with a 3270 emulator, simulating operator keyboard actions. API programs often are written to automate host log-on procedures.
APPC
Advanced program-to-program communications consists of a set of IBM protocols that application programs running on different processors used to communicate with each other directly, without passing through the mainframe.
Appletalk
A proprietary local area network developed by Apple Computer to link Macintosh computers and peripherals, especially printers.
Application Layer
Layer 7 of the open system interconnect (OSI) model for data communications. It defines protocols for users or application programs. APPN Advanced peer-to-peer networking is a network architecture that allows mainframes, minicomputers and PCs to communicate as peers across LANs and WANs
Approved Ground
Only as specified in NEC (National Electrical Code Handbook). Refer to articles 250-24, 250-50, 250-71, 250-80, 250-81, 800-33 - 800-40 for compliant approved grounding methods and procedures. Refer to EIA/TIA 607 for standard telecommunications grounding.
Aramid Yarn
Strength elements that provide tensile strength and provide support and additional protection of the fiber bundles.
Architecture
The manner in which a system (infrastructure, hardware and software) is designed. Architecture usually describes how the system is constructed, how the components fit together, and the protocols and interfaces used to integrate these components. It also defines the functions and description of data formats and procedures used for communication between nodes and workstations.
ARCnet
A 2.5 Mbps baseband, token-passing network, designed by Datapoint Corporation, that supports up to 255 nodes.
Armor
Additional protective element beneath outer jacket to provide protection against severe outdoor environments. Usually made of plastic-coated steel, it may be corrugated for flexibility.
Array Connector
A connector that aligns and protects fibers from a ribbon fiber optic cable. A fanout array design can be used to connect ribbon fiber optic cables to nonribbon cables.
ASP
Aluminum-steel-polyethylene, the preferred sheath for filled cable.
Asynchronous Transmission
A data transmission technique controlled by start and stop bits at each end of a character and characterized by an undetermined time interval between characters.
Attachments
A general term to include straps, bolts, clamps or brackets used to support cable in an aerial distribution scheme.
Attachment Unit Interface (AUI)
Branch cable interface located between a media attachment unit and a data station.
Attenuation
The decrease in magnitude of power of a signal in transmission between points. For example, in fiber, expresses the total loss of an optical fiber consisting of the ratio of light output to light input. Attenuation is measured in decibels (fiber or copper) per kilometer (dB/km) at a specific wavelength or frequency. The lower the number, the better. Typical multimode wavelengths are 850 - 1300 nanometers (nm) and singlemode are at 1300 - 1550 nm. Copper is now characterized up to 350 MHz plus.
Attenuation Constant
A rating for a cable or other transmitting medium, which is the relative rate of amplitude decrease of voltage or current in the direction of travel.
Attenuation-Limited Operation
The condition in a fiber optic link when operation is limited by the power of the received signal (rather than by bandwidth or by distortion).
Audio
A term used to describe sounds within the range of human hearing. Also used to describe devices which are designed to operate within this range. (Ex: telephone 300 Hz-3400 Hz.)
AWG
American Wire Gauge
AWM
Appliance Wiring Manual
BDF
Building distribution frame. Primary location for administration of "backbone" cable for a particular building. May reside in same location as B.E.T. (BET) and/or MDF. While BDF implies that there is one distributing frame for a building, there may be IC/TC (IDF) locations that serve as cross-connect locations beyond the BDF. Usually located at, or near, telco entrance facilities (basement, mechanical cores, utility tunnels, etc.) may also be MPOE (minimum point of entry) (telco) location. Terminology varies - see ANSI/EIA/TIA 568A or latest revision, and EIA/TIA 569.
BET
Building entrance terminal, aka entrance facility. Usually the nearest location within a structure that permits termination and protection of telco entrance cable(s). May also serve as MDF and/or BDF. In some situations, the BET is co-located with, or serves as, PABX or key equipment room, MDF and/or BDF and may contain all associated power, battery and other communications equipment. See EIA/TIA 568A, 569. Terminology varies.
Backboard
A rigid support for mounting telecommunications terminating hardware, blocks, cross-connect components and wiring. May also be used to attach and support entrance and distribution cables, splice cases, etc. Typically 3/4 in. plywood anchored/fastened to existing wall. It is recommended that the plywood be fire-retardant, or be coated with a fire-retardant substance.
Backbone Cable
Typically considered to be horizontal or vertical distribution cable. Connects entrance facility to various floors or telecommunications closets. Some versions are shielded. Should be placed near central axis of building for protection and minimized risk of lightning strikes.
Back-End
Database server functions and procedures for manipulating data.
Background Process
When the PC is running more than one program at the same time, a background program or process is one that is sharing memory and CPU time with another active program, but is not interacting with the user. The background program may be waiting for input from the keyboard, but runs by itself in memory while another (foreground) program controls the keyboard and display.
Backscattering
The return of a portion of scattered light to the input end of a fiber; the scattering of light in the direction opposite to its original propagation.
Balanced Line
A cable having two identical conductors opposite in polarity and equal in magnitude and transmission characteristics, with respect to ground. See Balun.
Balloon Framing
A method of framing a structure with strength members, characterized by studs that run from basement to roof without interruption.
Balun
Balanced/unbalanced device used when interconnecting balanced circuits with unbalanced circuits, such as coaxial cables to balanced unshielded or shielded twisted pair (UTP-STP).
Band
A range of frequencies between two predetermined limits.
Bandwidth
The range of frequencies that can be used for transmitting information on a channel, equal to the difference in Hertz (Hz) between the highest and the lowest frequencies available on that channel. Bandwidth indicates the available frequency of a channel. Thus, the larger the bandwidth, the greater the amount of information that can pass through the circuit.
Bank
(a) A range of frequencies between upper and lower limits or (b) a group of tracks on a magnetic drum or magnetic disc or (c) telco carrier equipment (channel bank).
Barrier
A permanent partition installed in a cable raceway or housing that provides complete separation of the adjacent compartment.
Baseband Network
A network in which the entire bandwidth of the transmission medium is used for the signal. Unlike broadband, no characteristic modulation techniques are used.
Baseboard Raceway
A distribution method in which metal or wood channels, containing cables, run along the baseboards of a building. The front panel of the baseboard channel is removable, and information outlets may be placed at any point along the channel.
Basic Rate Interface (BRI)
ISDN standard interface to serve sources or destinations of relatively small capacity, such as terminals. Two "B" channels (64 kbps) and one "D" channel (16 kbps).
Batch
The batch method of processing occurs when data is collected over a period of time and then processed as a batch rather than as it becomes available.
Baud
Unit of data transmission speed meaning bits per second (500 baud = 500 bits per second). Less commonly used as technology permits much faster speeds.
Beamsplitter
An optical device, such as a partially reflecting mirror, that splits a beam into two or more beams and that can be used in fiber optics for directional couplers.
Bearing Wall
A wall that supports a load other than its own weight (upper floor, roof, etc.).
Bel
A unit that represents the logarithm of the ratio of two levels. The number of bels is equal to the logarithm 10 (P1/p2); 2 logarithm 10 (E1/E2); and 2 logarithm 10 (l1/l2). See dB.
Bend Loss
A form of increased attenuation caused by (a) having an optical fiber curved around a restrictive radius of curvature or (b) microbends caused by minute distortions in the fiber imposed by externally induced perturbations.
Bend Radius
Measure for copper cable or optical fiber bends. Refer to manufacturer’s recommendations for specific minimum bend radius. Typically 4X, 6X or 10X the outside diameter dependent on specific performance characteristic limitations.
BGX
below ground fiber cross-connect system
BIC
building industry consultant
BICSI
Building Industry Consulting Services International
Binary Digit (BIT)
The smallest unit of information (data) and the basic unit in data communications. A bit can have a value of zero or one (a mark or space).
Binder (cable)
A tape, film or thread used for holding assembled cable conductors in place.
Bit
One binary digit.
Bit/s (BPS)
Bits per second. A measure of speed or data rate. Often combined with prefixes such as Kbps (kilo or thousands of bits per second) and Mbps (mega or millions of bits per second).
Bit Error Rate
The number of erroneous bits compared to the total number of bits transmitted over a fixed period of time.
Blue Field
The field used in telecommunications closets or equipment rooms to connect stations to the horizontal segment. Systems other than fiber distributed data interface (FDDI) can also be connected to the blue field. In twisted pair environments, the blue field terminates cable from the information outlet.
BNC Connector
Coaxial connector type used on many types of data communications equipment.
Bonding
A low-resistance path obtained by joining all current-carrying metallic elements to assure electrical continuity, and having the capacity to safely conduct any current introduced into the path.
Booster
A device or amplifier inserted into a line or cable to increase the voltage. Transformers may be employed to boost AC voltages. The term booster is also applied to antenna preamplifiers.
Braid
A group of textile or metallic filaments interwoven to form a tubular flexible structure which may be applied over one or more wires, or flattened to form a strap (as in bonding braid).
Breakout Cables
Multi-fiber compositions where each fiber is further protected by an additional jacket and optional strength elements.
Break Test Access
Method of disconnecting a circuit which 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 patching devices.
Bridge
Linking together two or more networks by a device. A bridge is capable of providing logical routing of frames between rings based on routing information contained in the frames.
Bridging Connection
A parallel connection through which some of the signal energy in a circuit may be withdrawn, usually with imperceptible effect on the normal operation of the circuit.
Broadband
Denotes transmission facilities capable of handling frequencies required for high-grade communications. Broadband infers the use of carrier signals as opposed to direct modulation. Characteristically used for simultaneous multi-channel transmission.
Broadcast
The address for all nodes in a network or the message sent to all nodes.
Brouter
A device that can route specific protocols and bridge others, thus combining the capabilities of a bridge and a router.
Brown Field
The field used in telecommunications spaces to terminate campus backbone cables.
Buffer or Buffering
(a) Protective material extruded directly on the fiber coating to protect it from the environment (tight buffered); or (b) extruding a tube around the coated fiber to allow isolation of the fiber from stresses in the cable (buffer tubes).
Buffer Tubes
Extruded cylindrical tubes covering optical fiber(s) used for protection and isolation.
Building Core
That portion of any building devoted to stairwells, elevators, rest rooms, utility, mechanical, electrical, HVAC and telecommunications cabling/equipment.
Building Entrance Area
The area inside a building where cables enter and may be connected to riser/backbone cables and where electrical protection is provided. The network interface, as well as protectors and other distribution components for campus backbone subsystems, may also be located here. See BDF, BET.
Building Footing
The concrete base under the foundation of a building, in which copper wire may be laid to form an electrical ground.
Bundle
Many individual fibers contained within a single jacket or buffer tube. Also, a group of buffered fibers distinguished in some fashion from another group in the same cable core.
Buried Cable
A gel-filled, mechanically protected cable that is direct buried in a trench in such a fashion that it cannot be removed without excavation (FED-std-1037A). As a general reference to types, characteristics and makeup, refer to AT&T Outside Plant Systems, Issue 3 or later. Not to be confused with underground cable (in ducts).
Buried Distribution Method
The method of running cable underground between buildings in campus systems by burying the cable in a trench.
Bus
(a) data path shared by many devices or (b) a linear network topology in which all workstations are connected to a single cable. On a bus network, all workstations receive all transmissions; only the workstation that the information is addressed to will use the information. Contrast with ring and star.
Busbar Wire
Minimum #6 AWG copper wire in telecommunications.
Bus Interface Unit (BIU)
The data circuit equipment that provides physical access to the bus.
Bus Topology
A local area network (LAN) topology in which endpoints connect to a single cable or fiber, or set of wires or fibers, at any point.
Butyl Rubber
A synthetic rubber with good electrical insulating properties.
Byte
A group of eight bits makes a byte. Typically a 16 bit "word" is itself divided up into two bytes for handling. A byte is usually the smallest addressable unit of information in a data store or memory.
C
Symbol designation for capacitance and Celsius..
Cabinet
An enclosure that may house connection devices, terminated cables, splices, apparatus, wiring and equipment. Typically affords security and/or protection from prevailing conditions such as weather, vandalism or accidental damage.
Cable Assembly
(a) Optical fiber cable that has connectors installed on one or both ends (also applies to copper). General use of these cable assemblies include the interconnection of optical fiber cable systems and opto-electronic equipment. If connectors are attached to only one end of a cable, it is known as a pigtail. If connectors are attached to both ends, it is known as a jumper or patch cord. (b) The method by which a group of insulated conductors is mechanically assembled or twisted together.
Cable Attenuation
The measure of the loss in electrical strength encountered by signals sent through cable.
Cable Bend Radius
Cable bend radius during installation infers that the cable is experiencing a tensile load. Free bend infers a small allowable bend radius since it is at a condition of no load.
Cable Budget
The equivalent electrical cable, as an example, length between the Token Ring adapter card (DB9 Connector) and the media interface connector (MIC) on the multistation access unit (MAU) plus adjusted main ring length (AMRL).
Cable Grip
A device that slips over the end of a cable and connects to a winch or hand line to assist in pulling cable during installation.
Cable Listings
National Electrical Code (NEC)
Article 800:
MPP Multipurpose Plenum
MPR Multipurpose Riser
CMP Plenum Rated Communications Cable
CMR Riser Rated Communications Cable
CM General Purpose Not Used In Plenums Or Risers
CMX Residential And Restricted Commercial Use
Article 700:
OFC Optical Fiber, Conductive
OFCP Optical Fiber, Conductive, Plenum
OFCR Optical Fiber, Conductive, Riser
OFN Optical Fiber, Non-Conductive
OFNP Optical Fiber, Non-Conductive, Plenum
OFNR Optical Fiber, Non-Conductive, Riser
Refer to appropriate articles of the NEC handbook for details on ratings and specific approved applications.
Cable Plant
The cable plant consists of all the optical elements, for example, fiber, connnectors, splices, etc. between a transmitter and a receiver.
Cache
Memory location set aside to store frequently accessed data for improved system performance.
CAD/CAM
(a) computer-aided design/computer-aided manufacturing or (b) computer-aided drafting/computer-aided management.
Campus
The buildings and contiguous property of a complex, such as a university, college, industrial park, military establishment, municipality or health care facility, to name a few.
Campus Backbone Cable
The communications cable that is part of the system and runs between buildings. Typical methods of installing campus backbone cable: in-conduit (underground conduit), direct-buried (in trenches), aerial (on poles), and in-tunnel (in steam tunnels).
Campus Cable Entrance
The point at which campus backbone system cabling (aerial, direct-buried, or underground) enters a building.
Capacitance
The property in a system of conductors and dielectrics that permits the storage of electrical charges whenever a difference in potential exists between the conductors. Capacitance is undesirable in copper cable because it interferes with signals by opposing the desired flow of current.
Capacitive Reactance
The opposition to alternating current due to the capacitance of a cable or circuit. It is measured in ohms and is equal to 1/6.28fC where f is the frequency in Hz and C is the capacitance in farads.
Capacitor
Two conducting surfaces separated by a dielectric material. The capacitance is determined by the area of the surface, type of dielectric, and spacing between the conducting surfaces.
Carbon Block
A surge-limiting device that is grounded by arcing across the air gap when the voltage of a conductor exceeds a predetermined level. If the current flow across the gap is large or persists for a length of time the protector mechanism will operate and the protector will become permanently grounded.
Carrier
A company which provides network transmission services or (b) a continuous electrical signal capable of being modified to carry information. The carrier carries no information until some component of the signal (amplitude, frequency or phase) is changed. These changes convey the information.
Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA)
Network access method using contention similar to carrier sense multiple access/collision detection (CSMA/CD) used by LocalTalk Networks. Unlike CSMA/CD, in this method, the sending node responds with a clear-to-send signal before transmission begins.
Carrier Sense Multiple Access/Collision Detection (CSMA/CD)
Network access method in which nodes contend for the right to send data. If two or more nodes attempt to transmit at the same time, they abort their transmission until a random time period of microseconds has transpired and then attempt to resend.
Cascaded Stars
Topology in which a centralized multiport repeater serves as the focal point from many other multiport repeaters, also known as hierarchical star.
Category 1-5 Cabling
(Structured Wiring)
Cat 1 POTS Voice And Low-Speed Data.
Cat 2 ISDN, Low-Speed Data, 4 Mbps Token Ring
Cat 3 Cables/connecting hardware with transmission characteristics up to 16 MHz
Cat 4 Cables/connecting hardware with transmission characteristics up to 20 MHz
Cat 5 Cables/connecting hardware with transmission characteristics up to 100 MHz and beyond
CATV (Community Antenna Television/Cable Television)
A method of delivering high-quality television reception by transmitting signals from a central antenna throughout the community, via fiber and coaxial cable. CATV is a broadband transmission facility which generally uses a 75 ohm coaxial distribution drop cable to carry numerous frequency-divided TV channels simultaneously.
CB
Citizens band
CCTV
Closed-circuit television
CDDI
Copper distributed data interface is the term used for a copper cable on which a high-speed (100 Mbps) data is run. Called FDDI over fiber (fiber distributed data interface).
Ceiling Distribution Systems
Distribution systems that use the space between a suspended or false ceiling and the structural floor of the story above for placing the cable. Methods include zone, poke-through, conduit, raceway and cable trays.
Cellular Floor Method
A floor distribution method in which cables pass through floor cells, constructed of steel in concrete, that provide a ready-made raceway for distributing power and communications cables (separately).
Cellular Polyethylene
Expanded or foam polyethylene, consists of individual closed cells of inert gas suspended in a polyethylene medium, resulting in a desirable reduction of the dielectric constant.
Center Wavelength (Laser)
The nominal value central operation wavelength. It is the wavelength defined by a peak mode measurement where the effective optical power resides.
Center Wavelenth (LED)
The average of the two wavelengths measured at the half amplitude points of the power spectrum.
Centralized Cabling
A cabling topology used with centralized electronics connecting the horizontal cabling with intrabuilding backbone cabling in the telecommunications closet.
Central Member
The center component of a cable. It serves as an anti-buckling element to resist temperature-induced stresses. Sometimes serves as a strength element. The central member material is either steel, Fiberglas, or glass-reinforced plastic.
Central Office
Facility where common carriers originate subscribers circuits and where the switching equipment that interconnects those circuits is located.
Central Office Local Area Network (CO LAN)
A LAN data switching system typically located at the local telephone company’s central office and used for providing advanced features or service to customers, Ex: centrex features.
Central Processing Unit (CPU)
(a) personal computer’s (PC’s) primary microprocessor chip or (b) host computer, centralized PABX or other central electronic intelligence.
Characteristic Impedance
A frequency-dependent resistance that quantifies the complex opposition to current flow offered by a transmission line.
Chromatic Dispersion
Spreading of a light pulse caused by the difference in refractive indices at different wavelengths.
CICS
The Communications Information Control System is a mainframe database application designed for remote access via the systems network architecture (SNA).
Circuit
A two-way communication path between electronic devices.
Circuit Mil
A term used to define cross sectional areas using an arithmetic shortcut in which the area of the round wire is taken as diameter in mils (.001") squared.
Cladding
The low refractive index material that surrounds the core of an optical fiber, usually silica.
Cleave
The process of separating an optical fiber by a controlled fracture of the glass, for the purpose of obtaining a fiber end, which is flat, smooth, and perpendicular to the fiber axis.
Client
A node that requests network services from a server.
Client-Server Computing
A technique by which processing can be distributed between nodes requesting information (clients) and those maintaining data (servers).
Closed Architecture (Proprietary System)
An architecture that is compatible only with hardware and software from a single vendor. Contrast with Open Architecture.
Closet
Typically a location for hardware, conduit, power panels and electronics, such as multiplexers and concentrators. See Telecommunications Closet (TC).
Cluster
A collection of terminals or other devices in a single location.
COAM
customer owned and maintained
Coating
A protective layer of material over the cladding of an optical fiber.
Coax Connection
Coax connection consists of the link established between a PC and a cluster controller via coaxial cable.
Coaxial Cable
A cable with one transmission conductor (inner conductor) and an outer conductor/braid/shield insulated from one another by a dielectric foam.
CODEC (Coder/Decoder)
Equipment used to transform analog voice signals to digital signals (coder) and digital signals to analog signals (decoder). May be in digital PABX or in the device/instrument itself.
Coherent Light
Parallel, narrow band of light of the same wavelength and phase.
Coil Effect
The inductive effect exhibited by a spiral-wrapped shield, especially above audio frequencies.
Collapsed Backbone
A local area network configuration wherein bridging and routing functions are located at the main cross-connect and accessed via concentrators at the horizontal cross-connects.
Color-Coded Cable
Cable having color-coded insulation on the conductor to aid identification.
Common Carrier
A private communications utility company or a government regulated organization that furnishes services to the general public. It is typically licensed or regulated by a state or federal government agency.
Communication Network
Hierarchy of stations capable of intercommunications, but not necessarily on the same channel or circuits.
Communication Power Pole
A raceway placed between the ceiling and floor used in conjunction with a ceiling distribution system for the purpose of distributing communication and power service to a work area. Also called utility column, ceiling drop pole or power pole.
Communications System
A collection of individual communications networks, transmission systems, relay stations, tributary stations, and terminal equipment capable of interconnection and inter-operation to form an integral whole. These individual components must serve a common purpose, be technically compatible, employ common procedures, respond to some form of control and, in general, operate in unison.
Composite Cable
A cable construction technique that combines multiple cables or media in a single overjacket.
Computer Peripherals
The auxiliary devices under control of a central computer, such as card punches and readers, high-speed printers, magnetic tape units and optical character readers.
Concentrator
A type of station defined in the fiber distributed data interface (FDDI) station management (SMT) standard. Concentrators can be connected to other concentrators to form a single-ring/tree offshoot from the main dual ring. Concentrators are used to divide a data channel into two or more channels of average lower speed, dynamically allocating space according to demand, to maximize data throughput at all times. Also called an intelligent time division multiplexer (TDM), asynchronous time division multiplexer (ATDM), or statistical multiplexer.
Concentric Stranding
A group of uninsulated wires twisted together and containing a center core with subsequent layers spirally wrapped around the core to form a single conductor.
Concurrency
This term refers to the ability of some emulation programs to allow DOS programs to run in the background while 3270 emulation runs in the foreground.
Conductivity
The ability of a material to allow electrons to flow, measured by the current per unit of voltage applied. It is the reciprocal of resistivity.
Conductor
A medium such as copper wire that can carry electrical current.
Conduit
A pipe, usually metal, that runs underground, from floor to floor, or along a floor or ceiling to protect cables. In the riser backbone subsystem when riser telecommunications closets are not aligned, conduit is used to protect cable and to provide the means for pulling cable from floor to floor. In the horizontal subsystem, conduit may be used between a telecommunications closet and an information outlet in an office or other room. Conduit is also used for campus distribution, where it is run between buildings and intermediate manholes and is made of PVC occasionally encased in concrete. Multiduct conduit may also be used.
Conduit Sizing
All INC (intra and interbuilding network cabling) conduits should be sized at a minimum of 4 inches. When placing new conduits, size installation to include one spare 4" conduit for future. All INC cores and sleeves should meet same criteria (min. 4 in.).
Connecting Block
A flame-retardant plastic block containing metal wiring terminals (clips) that establish an electrical connection between the cable and the cross-connect wire.
Connecting Hardware
A device used to terminate cable with connectors and adapters that provides an administration point for cross-connecting between cabling segments or interconnecting to electronic equipment.
Connector
A device to connect and disconnect copper wires or fibers in cable to equipment or to other wires or fibers. Copper wire and fiber optic connectors most often join transmission media to equipment or cross-connects.
Connector Panel
A panel designed for use with patch panels; it contains either 6, 8, or 12 adapters pre-installed for use when field-connectorizing fibers.
Connector Panel Module
A module designed for use with patch panels; it contains either 6, 8, or 12 connectorized fibers that are spliced to backbone cable fibers.
Contention
Network access method in which nodes compete for transmission by sending signals at will.
Controller
(a) A device used to control the input/output operations between the host computer and a group of terminals.
Control Unit Terminal (CUT)
CUT refers to the connection of a single-session terminal device to a cluster controller.
Controller
(b) In an SNA environment, the controller refers to IBM Cluster Controllers, devices that interface display terminals and printers to the host computer.
Convector Area
An area allocated for heat circulation and distribution. Convector areas, typically built into a wall, can be used as a satellite location only if a more suitable area is unavailable.
Convergent Light
Rays coinciding in one point.
Cord
A flexible insulated cable (stranded vs. solid conductors).
Core
(a) The central transmission area of a fiber. The core always has a refractive index higher than that of the cladding or (b) section of building dedicated to utilities, HVAC, mechanical, electrical, etc. See building core.
Corona
The ionization of gasses about a conductor that results when the potential gradient reaches a certain value.
Coulomb
A quantity of electrically transferred by a current of one ampere (1 A) in one second.
Coupler
A multiport device used to distribute optical power.
Coupling
The transfer of energy between two or more cables or components of a circuit.
CPE
Customer remises (or provided) equipment. Equipment residing on customer sites such as, PABX systems, key systems, data devices, etc. This term is frequently interchanged with "station equipment" in protection practices.
CPUC
California Public Utilities Commission
Critical Angle
That angle of incidence, at which total reflection is obtained.
Cross-Connect
System component where communication circuits are administered (that is, added or rearranged using jumper wire or patch cords). In 110 connector systems, jumper wire or patch cords are used to make circuit connections. In fiber optic connector systems, fiber optic patch cords are used. The cross-connect is located in an equipment room or telecommunications closet.
Cross-Connect Field
Copper wire or fiber terminations grouped to provide cross-connect capability. The groups are identified by color-coded sections of backboards mounted on the wall in equipment room or telecommunications closets, or by designation strips or labels placed on the wiring block or unit. The color-coding identifies the type of circuit that terminates at the field. See EIA/TIA 606.
Cross Pinning
A wiring configuration that permits two DTE devices to two DCE devices to communicate, when straight-through pinning (568A/568B) cannot be used.
Crossover
A conductor which connects to a different pin number at each end. See Cross Pinning, above.
Crosstalk
Undesired signals in one circuit as a result of inductive coupling from another circuit. See Near End Crosstalk (NEXT).
CRT
cathode ray tube
CSA
Canadian Standards Association. Compare with EIA/TIA.
Current, Alternating (AC)
An electric current that periodically reverses direction of electron flow. The rate at which a full cycle occurs in a given unit of time (generally a second) is called the frequency of the current as in 60 cycle (hertz) AC.
Current, Direct (DC)
Electrical current whose electrons flow in one direction only. It may be constant or pulsating as long as its movement is in the same direction.
Current Loop
A two wire transmit/receive interface.
Cut-Down
A method of securing a conductor to a wiring terminal. The insulated conductor is placed in the terminal groove and pushed down with a special tool. As the conductor is seated, the terminal cuts through the insulation to make an electrical connection, and the spring-loaded blade of the tool trims the conductor flush with the terminal. Also called punch-down.
Cutoff Frequency
The lowest possible frequency having a propagation mode.
Cut-through Resistance
The ability of a material to withstand mechanical pressure without damage.
CXC
Coaxial cable, CSA (Canadian Standards Association) cable designation.
Cyclic Redundancy Check (CRC)
A coded sequence of information allowing error checking and correction.
DAC
dual-attached concentrator
Daisy Chain
A cabling practice no longer recommended, where devices were connected from one to another in a chain configuration.
Data Circuit-Terminating Equipment (DCTE)
General terminology for data communications equipment such as a modem. A device that terminates a data communications session and provides encoding or conversion if necessary (for example, modems or printers).
Data Communication
The movement of encoded information by means of electric transmission systems via one or more data links according to protocol.
Data Communications Equipment (DCE)
A device that establishes, maintains, and terminates a data communications session and provides encoding or conversion if necessary.
Data Concentrator
A device that permits a common transmission medium to serve more data sources than there are channels currently available within the medium.
Data Connector
IBM refers to the multistation access unit’s (MAU’s) port connector as a data connection. Certain applications use the term media interface connector (MIC) instead of data connector.
Data Link Control (DLC)
DLC is the protocol used by IBM or other vendors (Token Ring).
Data Link Layer
Layer 2 of the open system interconnect (OSI) model; it defines protocols governing data packetizing and transmission into and out of each node.
Data Packet Switch
System-common equipment that electronically distributes information among data terminal equipment connected to a data transmission network. The switch distributes information by means of information packets addressed to specific terminal devices.
Data Terminating Equipment (DTE)
General terminology for data equipment such as terminals and host computers. DTE can also stand for data terminal equipment. See DCTE.
Data Transmission
The sending of data from one place to another by means of a signal over a channel using various media.
DB9
A standardized connector with nine pins typically for Token Ring and serial connections.
DB15
A standardized connector with 15 pins typically for Ethernet transceivers.
DB25
A standardized connector with 25 pins typically for parallel-to-serial connections.
DC
direct current
Decibel (dB)
The standard unit for expressing transmission gain or loss and relative power ratios. The decibel is one tenth the size of a Bel, which is too large a unit for convenient use. Both units are expressed in terms of logarithm to the base 10 of a power ratio used primarily for attenuation and crosstalk measurements in telecommunications.
Decibel/kilometer (dB/km)
A unit of measurement for fiber optic attenuation.
Delay Line
A transmission line or equivalent device designed to delay a wave or signal for a specific length of time.
DEMARC
Demarcation point is the point of interface that readily identifies division of loop or circuit responsibility. Other terms frequently applied (properly or improperly): SNI (subscriber network interface), MPOE (minimum point of entry), EF (entrance facility) and others.
Demodulation
The process of extracting the information signal from an analog carrier signal. The reverse of modulation.
Demountable Walls
Metal walls that can be disassembled and moved to other locations. They contain vertical and horizontal slots through which cable can be run, aka: modular panels.
Deviation
Change in the direction of propagation
Dielectric
A nonconducting or insulating material that prevents passage of electric current and resists inductive coupling.
Dielectric Breakdown
Any change in the properties of a dielectric that causes it to become conductive. Normally a catastrophic failure of an insulation because of excessive voltage.
Dielectric Cable
A nonconducting cable, such as a fiber cable, without metallic members.
Dielectric Constant
Also called permitivity. That property of a dielectric which determines the amount of electrostatic energy that can be stored by the material when a given voltage is applied to it. Example: the ratio of capacitance of a capacitor using the dielectric to the capacitance of an identical capacitor using a vacuum as a dielectric.
Dielectric Heating
The heating of an insulating material when placed in a radio-frequency field, caused during the rapid polarization reversal of molecules in the material.
Dielectric Loss
The power dissipated in a dielectric as the result of the friction produced by molecular motion when a alternating electric field is applied.
Dielectric Strength
A measure of the maximum voltage that the insulation of a particular cable can withstand without breakdown.
Diffuse
The phenomenon when the molecules of two materials in contact mix.
Digital
A data format that typically uses two physical levels to transmit information. It is a discrete or discontinuous signal, on-off, zero-one, etc. MLT uses three levels instead of two.
Digital PBX (DPBX); also DPABX
A PBX (see Private Branch Exchange) designed to switch digital signals. Telephones used with a DPBX must digitize the voice signals, but computers and terminals may communicate directly through the DPBX, which functions as a point-to-point local area network through a central processor.
Digital Signal
A signal that represents information by a series of fixed, encoded, rectangular pulses, usually consisting of two possible voltage levels. Each voltage level indicates one of two possible values or logic states, such as on or off, open or closed, or true or false. See Digital, above.
Direct-Conduit Method
A ceiling distribution method in which cables are run in conduit from a centralized location directly to the desired information outlets.
Direct Distance Dialing (DDD)
The Bell System used for the telephone service in North America that enables a user to dial long-distance calls directly without operator assistance.
Disk/Disc
An electromagnetic storage medium for digital data.
Disk Server/Disc Server
A disk storage device which provides multiple users with access to their own assigned section of the disc. Compare with file server.
Dispersion
The cause of bandwidth limitations in a fiber. Dispersion causes a broadening of input pulses along the length of the fiber. Three major types are: (1) modal dispersion caused by differential optical path lengths in a multimode fiber; (2) chromatic dispersion caused by a differential delay of various wavelengths of light in a waveguide material; and (3) waveguide dispersion caused by the light traveling in both the core and cladding materials in singlemode fibers.
Display (Example:)
The display represents the PC monitor when it is running 3270 emulation. One PC monitor can emulate more than one 3270 terminal display.
Distortion
Any undesired change in a wave form or signal.
Distributed Architecture
A network that uses a shared communications medium (such as star, bus or ring LAN) and uses shared access methods.
Distribution Block/Frame
Centralized connection equipment where telephone or data terminal cabling is terminated and cross-connections are made.
Distribution Field
The cross-connect or interconnect field used to further distribute the cabling from one point in the network to another. Distribution fields are color coded by function (EIA/TIA 569).
Distribution Network
Part of the local exchange network, comprising small cables between subscribers’ distribution points (DPs) and cabinets, remote line units (RLUs) or other flexibility points.
Distribution Panel
Wall or rack mounted panel that permits accessible physical "patching", or cross-connecting of voice/data circuits and/or devices.
DLC
digital loop carrier also, SLC or subscriber line carrier
Drain Wire
An uninsulated wire in contact with a shield throughout its length. Used for terminating the shield, typically at the equipment end only.
Drop Cable
In a CATV system, the transmission cable from the distribution device to the structure being served.
DSX
digital signal cross-connect
Dual-Attached Station (DAS)
A station defined in the fiber distributed data interface (FDDI) standard that has two dual-fiber-optic connections (MIC A and MIC B) that allow it to be connected to the dual FDDI ring.
Dual-Fiber Cable
A type of fiber cable that has two single-fiber cables enclosed in a jacket of extruded polyvinyl chloride (PVC), with a rip cord for pulling back the jacket to access the fibers.
Dual Homing
The optional connection of dual-attached stations (DASs) to concentrators to increase reliability of the DAS network attachment.
Dual-Media Access Control (DMAC)
A station with two media access control (MAC) entities, which allow for logical connectivity to each of the dual FDDI rings. A DMAC station can independently send and receive data from both rings and thus has an available bandwidth of 200 Mbps from the network.
Ducts
Various pathways or conduits ranging from PVC to metallic to clay/tile. Example: the main feeder channels in which communication cable is routed between buildings in a campus environment.
Dumb Terminal
A dumb terminal is a device that can send and receive data but cannot process data.
Duplex
(a) In data communications, a circuit used to transmit/receive signals simultaneously in both directions, or (b) in general, two receptacles or jacks in a common housing which accepts two plugs.
E
Voltage also, EMF (electromotive force).
Earthing
British terminology for zero-reference ground.
Elastomer
Any material that will return to its original dimensions after being stretched or distorted.
Electromagnetic
Referring to the combined electric and magnetic fields caused by electron motion through conductors.
Electromagnetic Coupling
The transfer of energy by means of a varying magnetic field, also inductive coupling.
Electromagnetic Interference (EMI)
The interference in signal transmission or reception caused by the radiation of electrical and magnetic fields. See RFI, Radio Frequency Interference.
Electron Volt
A measure of the energy gained by a electron passing through an electric field produced by one volt.
Electronic Industries Alliance (EIA)
Governing agency for established standards and published test procedures. See CSA.
Electrostatic
Pertaining to static electricity, or electricity at rest.
Electrostatic Coupling
The transfer of energy by means of varying electrostatic fields. Capacitive coupling.
EMC
Electromagnetic compatibility or conformity.
Emergency Power
An alternate electrical supply source, separate and distinct from the primary electrical utility (generators, batteries, rectifiers, etc.). Typically referred to as "back up", "hot standby", standby, emergency generators, etc.
EMF
Electromotive force (voltage).
Emulator
An emulator is a computer system or component that functions as another type of computer system or component. (See Printer Emulator.)
Energy Dissipation
Loss of energy from a system due to the conversion of work energy into an undesirable form, usually heat. Dissipation of electrical energy occurs when current flows through a resistance.
Entrance Facility
Typically denotes any or all of the following: telecommunications space, equipment, support hardware, cables, connectors, blocks, protectors, sleeves, splices, or other items specific to the DEMARC or MPOE where telco responsibility ends and the customer’s begins. aka: telecommunications service entrance.
EPDM
Ethylene-propylene-diene monomer rubber. A material with proven electrical insulating properties.
EPR
Ethylene-propylene copolymer rubber. Another material with proven electrical insulating properties.
Equilay
More than one layer of helically laid wires with the length of the lay the same for each layer.
Equipment Closet
A termination point for customer premise cabling designed to offer access to common equipment. Closets generally serve a specific area. See Telecommunications Closet (TC).
Equipment Room (ER)
Area dedicated to housing equipment associated with telecommunications systems such as PABX, data, power, key and or peripheral components. (Also PABX Room, MDF.)
Equipment Subsystem
The part of a premises distribution system that includes the cable and distribution components in an equipment room and that interconnects system-common equipment, other associated equipment, and cross-connects.
Equivalent Electrical Cable Length (EECL)
The length of cable that provides the same electrical loss (dB/MHz) as the transmission path from A to B.
Equivalent Electrical Lobe Length (EELL)
The sum of the equivalent electrical cable length (EECL) of all the components in the path from the connector to the media interface connector (MIC).
Equivalent Electrical Main Ring Length (EEMRL)
The equivalent length of cable obtained by adding up the equivalent electrical cable length (EECL) of all the components in the intercloset cabling path. This should not include the short 2-ft. multistation access unit (MAU) patch cords that connect MAU ring segments in a closet.
Ethernet
A baseband local area network used for connecting computers and terminals, etc., within the same. Ethernet was marketed (and trade marked) by Xerox. It is the basis for the IEEE Standard 802.3.
EV
electron volt
Extrinsic Loss
In a fiber interconnection, that portion of loss that is not intrinsic to the fiber but is related to imperfect joining, which may be caused by the connector of splice.
Fall Time
The time needed for a pulse to fall from 90 percent to 10 percent of its maximum value.
Fan Out Cable
Multifiber cable constructed in the tight buffered design. Designed for ease on connectorization and rugged applications for intra- or inter-building requirements.
Farad
A unit of capacity that will store one coulomb of electrical charge when one volt of electrical pressure is applied.
FAS
Fire alarm and signal cable, CSA (Cabling Standards Association) cable designation.
Fasteners
A general term referring to the screws and anchors used to secure attachments to wood, concrete, brick or stone in a cable distribution scheme.
Fault Management
One of five categories of network management defined by the International Standard Organization (ISO). Detects, isolates and corrects network faults.
Fault Tolerance
The ability of a system to perform fault management and continue operating in the event of system failure.
FDI
Feeder distribution interface. Fiber distribution interface. Not to be confused with FDDI.
FDT
fiber distribution terminal
Federal Communications Commission (FCC)
A board of commissioners that regulates all electronic communications systems originating in the United States, including telephone systems.
Feedback
Energy that is extracted from a high-level point in a circuit and applied to a lower level. Positive feedback reduces the stability of a device and is used to increase the sensitivity or produce oscillation in a system. Negative feedback, also called inverse feedback, increases the stability of a system as the feedback improves stability and fidelity.
Feeder Cable
(a) In telecommunications, main distribution cable or trunk cable, or (b) in CATV, the transmission cable from the head end (signal pickup) to the trunk amplifier.
FEP
Fluorinated ethylene-propylene. A thermo-plastic material with superior electrical insulating properties and chemical and heat resistance, aka: TEFLON (DuPont).
Ferrous
Composed of and/or containing iron. A ferrous metal exhibits magnetic characteristics.
Ferrule
A mechanical fixture, typically a rigid tube, used to protect and align a fiber in a connector. Generally associated with fiber optic connectors.
FET
field effect transistor
Fiber
Thin filament of glass. An optical waveguide consisting of a core and a cladding that is capable of carrying information in the form of light.
Fiber Distributed Data Interface (FDDI)
An American National Standards Institute (ANSI) standard for a fiber-based physical and data line protocol that operates at a 100-Mbps data transfer rate.
Fiber Optic Cable
A transmission medium consisting of a core of glass or plastic surrounded by a protective cladding, strengthening material, and outer jacket. Signals are transmitted as light pulses, introduced into the fiber by a light transmitter (either a laser or light-emitting diode {LED}). Some of the advantages offered by fiber optic cable are low data loss, high-speed transmission, greater bandwidth, small physical size, light weight, and freedom from electromagnetic interference or electrical ground problems. Common types are single, dual, multifiber and ribbon.
Fiber Optic Connectors
Connectors designed to connect and disconnect either single or multiple optical fibers repeatedly. Fiber optic connectors are used to connect fiber cable to equipment and interconnect cables.
Fiber Optic Cross-Connection
Fiber optic apparatus for terminating cable in couplings. Designed for high-density cross-connection fields, the apparatus can terminate up to 72 fibers on each shelf, with up to nine shelves in a bay frame. Single shelves can also be wall mounted. Cross connections are handled with fiber optic patch cords.
Fiber Optic Interconnect
An interconnection unit used for circuit administration and built from modular cabinets. It provides interconnection for individual optical fibers but, unlike the fiber optic cross-connect panel, it does not use patch cords. The fiber optic interconnect provides some capability for routing and rerouting circuits, but is usually used where circuit rearrangements are infrequent.
Fiber Optics
The technique of conveying light or images through glass or plastic fibers. Coherent fiber optics should actually be called aligned fiber optics because the fibers are all the same length and are held in a constant spatial relationship.
Field
An area through which electric and/or magnetic lines of force pass.
File Server
A mass storage device that allows files to be accessed by several computers.
Fillers
Nonconducting components assembled with the insulated conductors or optical fibers to impart roundness, flexibility, tensile strength, or a combination of all three, to the cable.
Fire-Rated Doors
An assembly of various materials and types of construction used in wall openings to retard the spread of flames, gases and smoke.
Fire-Rated Poke-Through
A cable distribution device which is fitted through a predrilled core hole and allows cables to be fed from the floor below. A compartment at or above the floor surface is used to provide voice, data, power and video connections while maintaining the fire integrity of the floor.
Fire Resistance Rating
(Expressed in hours, or fractions of hours) Rating of designs or assemblies that show an acceptable resistance to fire (full scale); and, descriptions of materials or assemblies that withstand the passage of flame and heat transmission when exposed to fire under specified test and performance criteria. Reference to NFPA/NEC articles for specific rating.
Fire Shield
A material, device or assembly of parts in, or between, cabling systems, to prevent propagation of flames from one cable system to an adjacent cabling system.
Fire Wall
A wall that helps prevent fire spreading from one contained area to another and that runs from structural floor to structural ceiling.
Firebreak
A material, device or assembly of parts installed in a cable system to prevent the spread of fire along a cable system (not to be confused with fire barrier penetration). See Fire Shield.
Fireproof
A property in material such as masonry, block, brick, concrete or gypsum board that does not support combustion even under accelerated conditions.
Firestop Zoning
A unique group of architectural structure or assembles that prevents the passage of fire or toxicity from one contained area to another, thus reducing the possible spread of combustion through the fire barrier.
Firestop, Firestopping
(a) A material, device, or assembly of parts installed after penetration of a fire-rated wall, ceiling or floor area to prevent passage of flame, smoke or gases through the rated barrier. Refer to NFPA specifications for the intended application(s).
(b) The use of special devices and materials to prevent the outbreak of fire within telecommunications utility spaces and to block the spread of fire, smoke, toxic gases and fluids through openings, cable apertures and along cable pathways. The techniques used are often mandated by local building codes.
Note: Classifications are available under the rating criteria of ASTM E814.
Rating/Achievement:
F
Withstands the fire test for the rating period without: Permitting flames to pass through the firestop flame occurring on any element of the unexposed side of the firestop (auto-ignition) developing any opening in the firestop that permits a projection of water beyond the unexposed side during the hose strength test.
T
Meets the criteria of an "F" rating and prevents the transmission of heat during the rating period so that the temperature rise is not more than 325 degrees Fahrenheit on any exposed surface, thermocouple or penetrating item.
FITL
fiber in the loop
FLC
fiber loop converter
Flex Life
The ability of a cable to bend many times before breaking (stranded).
Flexibility
The ability of a cable to bend in a short radius.
Floor Box
A cast iron, stamped steel or nonmetallic box placed in the concrete floor (prior to pouring the concrete slab) of a building, which is fed via conduit and used to house voice, data, power or video connections.
FM
frequency modulation
Foam Polyethylene
Cellular polyethylene.
Foreground Process
When the PC is running more than one program at the same time, a foreground process or program is the one that currently controls the display screen and keyboard, and the one the user is interfacing with.
Frame
A metallic structure for supporting connectors, protectors, patch panels, blocks, etc.
Frequency
The number of cycles completed by a signal in one second (1 sec); expressed in Hertz (Hz). Example: 100 MHz.
Frequency Division Multiplexing (FDM)
A technique for combining many signals on a single circuit by dividing the available transmission bandwidth by frequency into narrower bands, each used for a separate communication channel.
Frequency Modulation (FM)
One of three basic methods (see also Amplitude and Phase Modulation) of adding information to a sine wave signal in which its frequency is varied to impose information on it.
Frequency, Power
Normally, the 60 Hertz power available in the United States
Frequency Response
The characteristic of a device denoting the range of frequencies over which it may be used effectively.
Fresnel
French physicist (1788-1827), one of the founders of the theory that light is an electromagnetic wave motion.
Fresnel Reflection Losses
Reflection losses that are incurred at the input and output of optical fibers due to the difference in refraction index between the core glass and immersion medium.
Front-end Processor (FEP)
An FEP is a computing device that handles communications tasks such as data transfer for the mainframe.
FTTC
fiber to the curb
FTTH
fiber to the home
Furniture System
Furniture walls combined with furniture units such as desks, work surfaces and file cabinets (modular furniture).
Furniture Wall
Hollow metal partitions with vertical and horizontal slots through which cable can be run. These walls can be covered with fabric, wood, veneer or other material and are usually from 48 to 72 inches high. See above.
Fuse
A UL-Approved overcurrent device with a circuit opening fusible part that is heated and severed by the passage of overcurrent through it.
Fusible Links
Short lengths of fine-gauge wires inside metallic sheath cable that melt to interrupt an electrical circuit and to prevent overheating or damage to wiring and equipment.
Fusion
A process for splicing optical fibers. See also mechanical splicing. Refer to technical specifications to determine which is most effective for intended applications.
FWHM
Full width half maximum, the width of a pulse at half its maximum.
Gain
The increase of voltage, current or power over a standard or previous reading. Usually expressed in decibels.
Gas Tube
A surge-limiting device similar in operation to a carbon block except that it has specially configured electronics with a more precise narrow gap (also available with a wide gap) and a sealed gas composition. The gas tube results in a more accurate and precise operating voltage range and extended service life under conditions of repeated operation.
Gas Tube Protector
An overvoltage protector featuring metallic electrodes which discharge in a gas atmosphere within a ceramic, glass or synthesized envelope.
Gateway
A device that converts protocols between dissimilar communications systems.
Gauge
A measure of a conducting wire’s physical size, usually referred to as AWG. See also American Wire Gauge (AWG).
Gigahertz (GHz)
A unit of frequency equal to 1 billion Hertz.
GND or GRD
Abbreviation for ground.
Graded Index Fiber
A fiber design in which the refractive index of the core is lower toward the outside of the fiber core and increases toward the center of the core. The refractive index bends the rays inward and allows them to travel faster in the lower index of refraction region. This type of fiber provides high-bandwidth capabilities.
Gray Field
The cross-connect field used in telecommunications closets to terminate horizontal cables that ties two closets together. As in IC to TC (EIA/TIA 568A/569).
Ground
An electrical connection to the earth, generally through a bonding conductor or ground grid. Also a common return to a point of zero potential, such as the main grounding busbar. See EIA/TIA 607.
Grounding
A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth, or to some conducting body that serves in place of the earth.
Grounding Conductor
The conductor used to connect electrical equipment to a grounding electrode. Also, bonding conductor.
Grounding Electrode
A conductor or group of conductors (usually a rod, or grid) in direct contact with the earth, providing a connection to the earth.
Ground Loop
A completed circuit between conductors created by random contact. An undesirable circuit condition in which interference is created by ground currents when grounds are connected at more than one point.
Ground Potential
The potential of the earth. A circuit, terminal, or chassis is said to be at ground potential when it is used as a reference point for other potentials in the system.
Half Duplex Transmission
Data transmission over a circuit capable of transmitting in either direction, but not simultaneously.
Handshaking
A preliminary procedure, usually part of a communications protocol, to establish a connection between devices.
HDSL
high bit rate digital subscriber line
Headerduct
The main or feeder duct for bringing cable from telecommunications closets to distribution ducts in cellular and underfloor duct systems.
Heat Coil
The device which grounds a conductor when the conductor’s current time limits are exceeded. Heat coils are suitable for sneak protection if they are located at the building entrance terminal (BET) aka entrance facility (EF).
Henry (H)
The standard unit of inductance. The inductance of a current is one Henry when a current variation of one ampere (1 A) per second is present at one volt (1 V).
Hertz
The unit of frequency, one cycle.
HF
high frequency
HiCAP
high capacity circuit (DS-1 and above)
Hierarchical Computer Network
A computer network in which processing and control functions are performed at several levels by computers specially tailored for the functions performed.
High Frequency
The band from 3 to 30 MHz in the radio spectrum, as designated by the Federal Communications Commission.
Home-Run Method
A distribution method in which individual cables are run directly from the telecommunications closet to each information outlet in a star configuration.
Horizontal Length (HL)
The cable distance from the work area outlet (WAO) to the specific field of the cross-connect (maximum 295 ft.) in the telecommunications closet (TC).
Horizontal Cabling
The portion of the cabling system extending from the work area outlet to the TC. The cross-connect facilities in the telecommunications closet are considered part of the horizontal cabling.
Host Computer
The central computer in a data communications system which provides the primary data processing functions such a computation, data base access, special programs or programming languages.
Hub
A concentrator or repeater in a star topology at which node connections originate. Hubs can be either active or passive.
Hum
A term typically used to describe the 600 cycle per second noise present in some communications equipment. Usually, hum is the result of undesired coupling to a 60 cycle source or to the defective filtering of ripple output of a rectifier.
Hybrid Cable
A cable containing two or more different types of cable, such as copper and fiber optic.
Hybrid Ring Control (HRC)
A Fiber Distributed Data Interface (FDDI) standard that allows the multiplexing of data packets and circuit-switched traffic on the FDDI local area network (LAN).
I
Symbol used to designate current (ampere).
IC
Intermediate cross-connect (EIA/TIA 568A/569). Formerly IDF.
ICEA
Insulated Cable Engineers Association
IF
intermediate-frequency
IFC or IFOC
Interfacility or intrafacility fiber optic cable
ILD
injection laser diode
IM
intensity modulation
Impedance
The total opposition that a circuit offers to the flow of current at a particular frequency. It is a combination of resistance (R) and reactance (X) and is measured in ohms.
Impedance, Characteristic
In a transmission cable of infinite length, the ratio of the applied voltage to the resultant current at the point the voltage is applied. Or the impedance which makes a transmission cable seem infinitely long, when connected across the cable’s output terminals.
Impedance, High
Generally, the area of 25,000 ohms or higher.
Impedance, Low
Generally, the area of 1 through 600 ohms.
Impedance Match
A condition whereby the impedance of a particular circuit cable or component is the same as the impedance of the circuit, cable or device to which it is connected.
Impedance Matching Sub
A section of transmission line or pair of conductors cut to match the impedance of a load. Also called matching sub.
Impedance Matching Transformer
A transformer designed to match the impedance of one circuit to that of another.
INC
Intrabuilding network cable. Also, interbuilding network cable. Cabling that comprises infrastructure beyond the telco MPOE. See Backbone Cable. MPOE.
Index-Matching Fluid
A fluid with an index of refraction close to that of glass that reduces reflections caused by refractive-index differences.
Index of Refraction
The ratio of light emissions in a vacuum relative to a given transmission medium.
Inductance
The electrical property of a circuit that induces change in existing current.
Induction Heating
Heating a conducting material by placing it in a rapidly changing magnetic field. The changing field induces electric currents in the material and dissipation accounts for the resulting heat.
Information Outlet (IO) aka: Work Area Outlet (WAO)
A connecting device designed for a fixed location (usually a wall or floor in an office) on which horizontal cable pairs terminate and which receives an inserted plug. It is the point where the horizontal system meets the work area. Although such devices are also referred to as phone jacks, the term information outlet or WAO encompasses the integration of voice, data and other communication services that can be supported via a premises distribution system.
Infrared Light
Light in the wavelength range 750-1000 nm heat radiation.
Infrastructure
See INC, backbone cable, riser. Encompasses all wire, cable, equipment, power, hardware, devices and associated components or labor to maintain operating systems beyond the telco MPOE (minimum point of entry).
Inhomogenity
Irregularity in e.g. the composition or geometry
Injection Laser Diode
Sometimes called a semiconductor diode. A laser in which the stimulation occurs at the junction of n-type and p-type semiconductor materials.
Innerduct
Flexible conduit originally produced for protection of optical fiber cables. See manufacturer’s standards for sizing and placement.
Input
A signal (or power) which is applied to a piece of electric apparatus, or the terminals on the apparatus to which a signal or power is applied to generate intelligent signal processing.
Insertion Loss
A measure of the attenuation of a device determining the output of a system before and after the signal is inserted into the system.
Institute of Electrical and Electronics Engineers Inc. (IEEE)
The standards group that develops standards for Token Ring, fiber distributed data interface (FDDI), 10BASE-T/FL, etc.
Insulation
A material having high resistance to the flow of electric current. Thin conducting wires are covered with color-coded insulation for protection and ease of identification.
Insulation Displacement
The type of wire terminals that require no insulation removal; when the conductor is correctly attached. The insulation is displaced (pierced) to form a connection.
Insulation Resistance
The measure of the ability of an insulation material to resist the flow of current through it; usually measured in Megohm-feet.
Insulation Stress
The molecular separation (pressure) caused by a potential difference across an insulator. The practical stress on insulation is expressed in volts per mil.
Integrated Services Digital Network (ISDN)
Integrated voice and data network based on digital communications technology and standards interfaces.
Integrated System
A telecommunications system that moves analog and digital traffic over the same network, including voice, data and video.
Intelligent Hub
A hub that performs bridging and routing functions in a collapsed backbone environment.
Intelligent Terminal
An input/output device, remote from its main computer, which contains an integral microprocessor capable of performing some amount of information storage or processing.
Interactive
Interactive, also referred to as on-line or real-time processing, occurs when the user is directly connected to the host and receives immediate response to requests or inquiries.
Intercloset Cables (more accurately, Backbone Cables)
Cables that connect telecommunications closets.