A-D
analog to digital conversion
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.
Interconnect
A circuit administration point, other than a cross-connect or information outlet, that provides capability for routing and rerouting circuits. It may not use patch cords. Typically it is a jack-and-plug device used in smaller distribution arrangements or to connect circuits in large cables to those in smaller cables.
Interface
The location where two systems or a major and a minor system meet and interact with each other.
Interface EIA Standard RS232 B/C/D
Standardized method adopted by the EIA to insure uniformity of interface between data communications equipment and data processing terminal equipment.
Interference
Disturbance of an electrical, electromagnetic or RFI nature that introduces undesirable responses into other electronic equipment.
Intermediate Cross-connect (IC)
In telecommunications, it is the space between MC and TC, if required.
Intermediate Frequency
A frequency to which a signal is converted for ease of handling. Receives its name from the fact that it is an intermediate step between the initial and final conversion or detection stages.
International Standards Organization (ISO)
The organization responsible for the open systems interconnect (OSI) standards among others.
International Telegraph and Telephone Consultative Committee (CCITT) aka: ITU-International Telecommunication Union(s)
A standards organization that, among numerous other activities, specializes in the electrical and functional characteristics of switching equipment. The CCITT sets standards to ensure compatibility between data communications equipment (DCE) and data terminating equipment (DTE).
Interoperability
The ability to operate and exchange information in a multivendor/multiproduct network.
Ionization Voltage
The potential at which a material ionizes. The potential at which an atom gives up an electron.
IPCEA
Insulated Power Cable Engineers Association
IR Drop
The value of a voltage drop in terms of current (ampere=I) and resistance (R).
IRS
ignition radiation suppression
Isolated Ground
A separate ground which is insulated from the equipment or building ground. Not recommended. See EIA/TIA 607.
Isolation
The ability of a circuit or component to reject interference.
IXC, IEC
Interexchange carrier. Ex: AT&T, MCI, US Sprint, Interdata.
Jack
A receptacle used with a plug to make electrical contact between communications circuits. Jacks and their associated plugs are used in a variety of connecting hardware applications including adapters, information outlets and equipment connections.
Jacket
The flexible covering of a cable, used to bind and protect the color-coded conductors inside.
Joule
A unit of energy, work or quantity of heat equal to 0.4342 foot-pounds. One Joule is the energy expended when a force of one Newton is applied over a displacement of one meter in the direction of the force.
Jumper
Optical fiber cable that has connectors installed on both ends.
Jumper Wire
Typically, a short length of copper used to route a circuit by linking two cross-connect termination points.
Junction Box
A connection point in a duct system that allows access to cables running in the ducts.
Keying
A mechanical mounting on connectors that can be used to prevent improper connection of station posts, as in "keyed" jacks/plugs.
Kilo
Metric prefix = one thousand.
KPSI
Tensile strength in thousands of pounds per square inch.
KV
kilovolt (1000 Volts)
KVA
kilovolt amperes
KW
kilowatt = 1000 watts
Label AA
Administration label for use on fiber optic cross-connect equipment which defines the fiber distributed data interface (FDDI) dual-ring assignments to the first four color-coded fibers in a building cable as follows:
fiber 1 (blue) - secondary input
fiber 2 (orange) - primary output
fiber 3 (green) - primary input
fiber 4 (brown) - secondary output
Label BB
fiber 1 (blue) - secondary output
fiber 2 (orange) - primary input
fiber 3 (green) - primary output
fiber 4 (brown) - secondary input
Label CC
fiber 1 (blue) - input
fiber 2 (orange) - output
fiber 3 (green) - input
fiber 4 (brown) - output
LAN NetView Management Utilities for OS/2
This software management package allows an administrator to view statistics and configure DOS, Windows, OS/2 or Macintosh workstations or servers from an OS/2 management console. It operates with LAN servers and NetWare networks.
Laser
(light amplification by stimulated emission of radiation) In telecommunications, a device which produces light at a narrow range of frequencies, to generate signals used in fiber optic communications systems.
LATA
Local access transport area. Regional TELCO Service, Interlata: See IXC.
Lay
Pertaining to wire and cable, the axial distance required for one cable conductor or conductor strand to complete one revolution about the axis around which it is cabled.
Lay Direction
The direction of the progressing spiral twist in a cable while looking along the axis of the cable away from the observer. The lay direction can be either left or right.
Lays
The twists in twisted pair cable. Two single conductors are twisted together to form a pair; by varying the length of the twists, or lays, the potential for signal interference between pairs is reduced due to canceling effect of emanated fields.
Lead-in
The cable that provides the path for RF energy between an antenna and a receiver or transmitter.
Leakage
The undesirable loss of signal over the surface of, or through, an insulator.
Leased Line
A private telephone line rented for the exclusive use of a leasing customer, without interexchange switching arrangements.
LED
See Light Emitting Diode.
Level
Typically, a measure of the difference between a quantity or value and an established reference.LF
Low frequency
Light Emitting Diode (LED Source)
A semiconductor device that emits light formed by the P-N junction. Light intensity is roughly proportional to electrical current flow.
Lightguide Building Cable (LGBC)
Alternative term used for a fiber cable in which individual optical fibers are stranded around central members. For interior use.
Lightguide Cross-Connect (LGX) Distribution System
A component of fiber optic connecting hardware. This component accommodates 24-216 fiber terminations. Also referred to as an LGX shelf or frame.
Lightguide Interconnection Unit (LIU)
A component of fiber optic connecting hardware. This component accommodates 12, 24 or 48 fiber terminations. Also referred to as an LIU. Not to be confused with Line Interface Unit (PABX).
Lightpack Cable
A cable core design that allows bundles of optical fiber in a cable core without central strength members.
Line Driver
A signal converter that conditions the digital signal transmitted by an RS232 interface to ensure reliable transmission beyond the standard RS232 limit and often up to several miles; it is a baseband transmission device. Also called a baseband modem, limited distance modem or short haul modem.
Line Drop
A voltage loss occurring between any two points in a power or transmission line. Such loss, or drop, is due to the resistance, reactance or leakage of the line. See Voltage Drop, IR Drop.
Line Equalizer
A reactance (inductance and/or capacitance) connected in series with a transmission line to alter the frequency-response characteristics of the line.
Line Level
Refers to the output voltage level of a piece of electronic equipment. Usually expressed in decibels.
Line Voltage
The value of the potential existing on a supply or power line.
Link
The communications circuit or transmission path connecting two points.
Link Budget
Optical loss budget that determines the maximum distance allowable between stations. Loss and dispersion factors are included.
Load
A device that consumes power from a source and uses that power to perform a function.
Loaded Line
A transmission line that has lumped elements (inductance or capacitance) added at uniformly spaced intervals. Loading is used to provide a given set of characteristics extending a transmission line.
Loading
See Loaded Line.
Lobe
In Token Ring networks, a 2-pair circuit connecting the adapter’s DB9 connector to the media interface connector (MIC) on the multistation access unit (MAU).
Lobe Length (LL)
The distance from the connector on a Token Ring adapter card to the media interface connector (MIC) on the multistation access unit (MAU). If this path has no intermediate connection points and is made up of one cable type, its effect on the Token Ring’s cable budget will contribute to the cable loss.
Local Area Network (LAN)
A data communications network consisting of host computers or other equipment interconnected to terminal devices, such as personal computers, often via twisted pair or fiber cables. LANs allow users to share information and computer resources. Typically, a LAN is limited to a single organization, department or geographic site.
Logical Unit (LU)
A device attached to the PC that is configured as a part of the network. These devices include displays and printers.
Logical Unit Address (LUA)
The host system address that identifies printers and displays attached to a PC.
Long-wire Antenna
Any conductor length in excess of one-half of a wavelength. In a television installation, a horizontal run of unshielded lead-in will act as a long-wire antenna and introduce additional signal on top of the regular antennae, signal causing "ghosts."
Loop
The cable pair which connects the customer to the switching center (ex: central office, main PABX). This path is called a loop because it is generally two wires out to the customer which are electrically tied together through the terminal set (device, instrument) when the device goes off-hook, creating a continuous path, or "loop."
Loopback
A type of diagnostic test in which a transmitted signal is returned to the sending device after passing through a data communications link or network. This test allows the comparison of a returned signal with the transmitted signal.
Loose Tube Cable
Type of cable design whereby coated fibers are encased in buffer tubes offering excellent fiber protection and segregation.
Loss
The portion of energy applied to a system that is dissipated and performs no useful work, or contributes to system impairments.
Low Frequency
A band of frequencies extending from 30 to 300 KHz in the radio spectrum, designated by the Federal Communications Commission.
Mutual inductance
See Inductance.
MA
Milliampere; one-thousandth of an ampere.
Macrobending
Macroscopic axial deviations of a fiber from a straight line, in cotrast to microbending.
Mainframe
Typically, a large-scale computer normally supplied complete with peripherals and software by a single, large vendor, often with a closed architecture. (Not recommended.) See OSI.
Main Ring Length (MRL)
The sum of the length of the intercloset cables, not including the short 2-ft. multistation access unit (MAU) patch cords connecting multiple MAUs together, that form a Token Ring. In multiple-closet MAU rings, the signal must travel through multiple MAUs, the cables connecting closets, the short 2-ft patch cords connecting the MAU segments in a closet and the lobe length (LL) without exceeding the maximum attenuation limit. See Horizontal Length (HL).
Main Terminal
See MPOE, equipment room, BDF.
Mbps
Megabits per second. One million units (bits) of information per second. As in binary language 0 or 1.
MC
Main cross-connect. Formerly MDF. See EIA/TIA 569.
MDF
Main distribution (distributing) frame, no longer used. Replaced by MC (main cross-connect). Location within the building that serves as the main cross-connect point between telco entrance cables, backbone or distribution cables (intra- and inter- building cables). May also serve as, or be co-located with main telecommunications equipment room, housing PABX, key, data, power or other associated equipment. May also serve as B.D.F. within the building. See MPOE, BDF, BET, entrance facility, network interface, etc.
MDPE
Abbreviation used to denote medium density polyethylene. A type of plastic material used to make cable jacketing.
Mechanical Splicing
Joining two fibers together by permanent or temporary mechanical means (vs. fusion splicing or connectors) to enable a continuous signal.
Media Access Control (MAC)
Refers to both the media access portion of the interface standard and the hardware and firmware which implements this portion of the standard.
Media Interface Connector (MIC)
A port connector also known as a data connector on a multistation access unit (MAU) in a Token Ring environment; also a dual-fiber connector for fiber distributed interface (FDDI).
Mega
Prefix = million.
Megabaud (Mbaud)
One million baud.
Megabit (Mb)
One million binary bits.
Megabyte (MB)
One million binary bytes.
Megahertz (MHz) One Million Hertz (Cycles)
A bandwidth-length product rating: Bandwidth is found by multiplying length by bandwidth-length equation.
Metal Oxide Varistor (MOV)
An electronic component that provides protection from voltage surges by absorbing them and then dissipating the energy as heat.
Metropolitan Area Network (MAN)
An extended LAN operating within a metropolitan area and providing integrated services for real-time data, voice and image transmission.
MFD
Microfarad; one-millionth of a farad. See Capacitance.
MGN
Multiground neutral system. A utility power system where the neutral conductor is continuously present along with the phase conductors. The neutral conductor is connected to earth periodically along its route, typically four times per mile. (This is not permitted in premises wiring systems, since the neutral conductor is only allowed to be grounded at the service entrance, or at the source of a separately derived system.) Not typically a telecommunications concern. See EIA/TIA 607.
MHO
Unit of conductance equal to the reciprocal of the unit of resistance (ohm).
MHz
Megahertz. Analog Frequency Spectrum Unit, one million cycles per second.
Micro
Prefix meaning one-millionth.
Microbending
Curvatures of the fiber which involve axial displacements of a few micrometers and spatial wavelengths of a few millimeters. Microbends cause loss of light and consequently increase the attenuation of the fiber.
Microfarad
One-millionth of a farad. This is the common unit for designating capacitance in electronics and communications.
Microinch
One millionth of an inch.
Micron
A micrometer; One-millionth of a meter.
Microphonics
Noise caused by mechanical excitation of a system component. In a single-conductor microphone cable, for example, microphonics can be caused by the shield rubbing against the dielectric as the cable is flexed.
Mil
One-thousandth of an inch.
Milli
Prefix meaning one-thousandth.
Minicomputer
A small or medium scale central computer designed to be accessed by dumb terminals. Compare with Microcomputer and Mainframe.
MIPS
Millions of instructions per second. A measure of processing power.
Modal Bandwidth
Bandwidth limited by modal dispersion inherent in multimode fiber optic cable.
Modal Dispersion
Dispersion resulting from the different transit lengths of different propagating modes in a multimode optical fiber.
Mode
A variable wave traveling in an optical fiber.
Mode Field Diameter
The diameter of the one mode of light propagating in a singlemode fiber. The mode field diameter replaces core diameter as the practical parameter in singlemode fiber.
Modem
A modulator/demodulator unit used for data transmission. It converts digital data into analog tones when transmitting over standard voice-grade telephone lines and reverses this process when receiving.
Modem Eliminator
A device used in place of the pair of modems normally needed to connect a local terminal and computer. It allows DTE to DCE data and control signal connections not easily achieved by standard cables and connectors.
Modular Jack
A female telecommunications interface connector. Modular jacks are typically mounted in a fixed locations and may have 4, 6 or 8 contact positions. Not all positions need be equipped with contacts. See also Telecommunications Outlets.
Modular Plug
A male telecommunications interface connector. Modular plugs may have 4, 6 or 8 contact positions. Not all positions may be equipped with contacts.
Modulation
Altering the characteristics of a carrier wave to convey information. Modulation techniques include amplitude, frequency, phase, plus many other forms of on-off digital coding.
Molding Raceway Method
A cable distribution method in which hollow moldings support cables. Small sleeves of pipe can be placed in the wall behind the molding to allow cable to pass through the wall.
Mono Filament
A single strand filament as opposed to multiple braided or twisted filaments.
Monochromatic
Consisting of a single wavelength. In practice, radiation is never perfectly monochromatic but, at best, displays a narrow band of wavelengths.
MPOE
Minimum point of entry. Frequently, this location is coincident with the BET, BDF and/or in close proximity to, or co-located with, the main telecommunications equipment room or MDF (aka network interface, BDF, BET, MDF, equipment room). See MC, MDF.
Multifiber Cable
An optical cable containing two or more fibers, each providing a separate information channel.
Multimode Fiber
An optical waveguide in which light travels in multiple modes. Typical core/ cladding size (measured in micrometers) is 62.5/125.
Multiplexer (MUX)
A MUX alternates the access of several data communication devices to a single communication line, such that the line is shared among the devices, but each functions as if it had sole access to the line.
Multimode Fibers
Optical fibers that have a large core (25 to 300 um) and that permit nonaxial rays or modes to propagate through the core. 62.5/125 mc is the common standard core for premises distribution systems.
Multiplexing
The process of combining multiple signals, usually by time-division multiplexing (TDM) on a high frequency carrier, to optimize the use of available transmission media. Also, see FDM.
Multistation Access Unit (MSAU)
A concentrator or transceiver for connecting nodes to a transmission medium.
Multiuser Outlet
A telecommunications outlet used to serve more than one work area, typically in open-system furniture applications.
Mutual Capacitance
The capacitance between two conductors when all other conductors, including the shield, are bonded to ground.
MV
Millivolt; one-thousandth of a volt.
MVS
Multiple virtual storage - An IBM mainframe operating system.
MW
Milliwatt; one-thousandth of a watt.
Nanometer
A unit of measurement equal to one billionth of a meter.
Nanosecond
One billionth of a second.
NAP
Network access point. See MPOE, Network Interface (NI), MDF, etc.
National Electrical Code (NEC)
A nationally recognized safety standard for the design, construction and maintenance of electrical circuits. The NEC, sponsored by the National Fire Protection Association (NFPA), generally covers electrical wiring within buildings.
NEMA 6P
National Electrical Manufacturers Association - Waterproof rating.
Neoprene
A synthetic rubber with resistance to oil, chemical and flame. Also called polychloroprene.
NetBIOS
The Network Basic Input/Output System in an IBM-developed LAN interface standard. Application programs on personal computers use NetBIOs for peer computer communications. Computers use this standard to communicate with remote resources attached to the LAN.
Network
An interconnection of computer systems, terminals or data/voice communications facilities.
Network Architecture
A formalized definition of the structure and protocols of a computer network.
Network Communication Cable (NCC)
Network communication cable, often called NCC, is generally used in the riser backbone subsystems. The cable consists of 24-AWG, annealed-copper conductors insulated with color-coded polyvinyl chloride (PVC) in twisted pairs, encased in an outer PVC jacket whose frictional properties permit it to be pulled in conduit. This type of cabling used to be referred to as direct inside wire (DIW). Not rated Category 5.
Network Connectivity
The topological description of a network which specifies the interconnection of the transmission nodes in terms of circuit termination locations and quantities.
Network Interface (NI) or Subscriber Network Interface (SNI)
The location of all connections at which any network channel, service or tariffed offering is properly terminated in terms of: design, installation, maintenance parameters and a physical interface is provided for connection to the network.
Note: network interface can also mean the point of interconnection between one network and another, or a portion thereof (FED-STD-1037A).
NEXT
near end cross talk
Nibble
One half byte (4 bits).
Node
(a) in PABX architecture, a distributed location or remote cabinet/processor. (b) In Token Ring networks, a work station/device.
Noise
In a cable or circuit, any extraneous signal which tends to interfere with the signal normally present in or passing through the system. See NEXT.
NRZ
no return to zero
Null Modem
A device which allows the connection of two DTE devices by emulating the physical connections of a DCE device.
Numerical Aperture
The number that expresses the light-gathering point of an optical fiber.
NVP
Nominal velocity of propagation. Speed electrons travel relative to a percentage of the speed of light in a vacuum. Example: .70c expresses 70 percent of the speed of light.
Nylon
An abrasion-resistant thermoplastic with good chemical resistance.
Ohm
The unit of measurement of the volume resistivity of a cubic meter of material, as determined by measuring the DC resistance between any two opposite faces of the cube. For soil measurements, the resulting reading in ohms is the earth’s resistivity for that soil. When earth resistivity is expressed in ohm/centimeters, convert to ohms by dividing by 100.
Ohm’s Law
Stated E = IR, I = E/R or R = E/I, the current, I in a circuit, is directly proportional to the voltage E, and inversely proportional to the resistance, R.
ONU
optical network unit
Open Architecture
An architecture that is compatible with hardware and software multiple vendors. See OSI.
Open System Interconnect (OSI)
A collection of international protocol standards for data networking. Multivendor/multiproduct applications.
Optical Fiber
A thin filament of glass. Optical waveguide consisting of cladding and a core capable of carrying information in the form of light.
Optical Time Domain Reflectometer (OTDR)
An instrument that characterizes cable loss by measuring the backscatter and reflection of injected light as a function of time. It is useful for estimating attenuation and for locating splices, connections, anomalies and breaks.
Optical Waveguide Fiber
A transparent filament of high refractive index core and low refractive index cladding that transmits light.
OSP
outside plant
Outer Protection
An outer layer of material, composed of armored wire or metallic tape, covering the sheath of the cable. Specified when additional mechanical protection is required due to external factors such as gophers, squirrels, rocks or other site specific requirements. Also known as armored cable.
Output
The useful power or signal delivered by a circuit or device.
Overfloor Duct Method
A distribution method that uses metal or rubber ducts to protect and conceal exposed wiring across floor surfaces.
Ozone
Extremely reactive form of oxygen, normally occurring around electrical discharges and present in the atmosphere in small but active quantities. In sufficient concentrations, it can break down certain rubber insulations under tension (such as a bent cable).
Packet(s)
Groups of bits, including address, data and control elements, that are switched and transmitted together.
Packet Switching
A data transmission method whereby data is transmitted in packets through a network to a remote location. The packet switch sends packets from different data conversations along the best route available in any order. At the other end, the packets are reassembled to form the original message which is then sent to the receiving computer. Because packets need not be sent in a particular order, and go any route as long as they reach their destination, packet switching networks can choose the most efficient route and send the most efficient number of packets down that route before switching to another route.
Pair
Two wires, grouped (usually twisted) together and marked with reciprocal color coding.
Parallel Circuit
A circuit in which the identical voltage is presented to all components, with current dividing among the components according to the resistance or the impedance of the components. Side by side versus end to end.
Parallel Transmission
A method of transmission in which all bits of a character are sent simultaneously over separate lines to a high-speed printer or other locally attached peripheral. Contrast with Serial Transmission.
PASP
Polyethylene-aluminum-steel-polyethylene, the preferred sheath for protection of cable against damage by lightning, mechanical means or rodents.
Passive Device
A component of the broadband system which is not supplied with activating power.
Patch Cord
A short length of stranded copper wire or fiber optic cable with connectors on each end used to join communication circuits at a cross-connect.
Patching
Connecting circuits by means of cords with plugs inserted into appropriate jacks.
Patch Panel
A device, usually located in a telecommunications closet, in which temporary or semi-permanent connections can be made between incoming and outgoing lines. Used for modifying or reconfiguring a communications system or for connecting devices such as test instruments to specific lines.
PCC
Premises communication cable, CSA (Canadian Standards Association) cable designation.
PCE
pole mount cable enclosure
Peak
The maximum instantaneous value of a varying current or voltage.
Pedestal
An enclosure, usually mounted on the floor, which is used to house voice/data jacks or power outlets at the point of use. Also referred to as a monument, tombstone, above floor fitting or doghouse.
Peer-To-Peer Communications
The ability of programs and devices to communicate directly with one another, without passing communications through the mainframe.
Periodicity
Uniformly spaced variations in the insulation diameter of a transmission cable that results in reflections of a signal.
Peripheral Equipment
Equipment which itself has no on-line role but works closely with on-line equipment, e.g., printers, modems, sorters, etc.
Personal Computer (PC)
A computer for personal, single-user use, as opposed to mainframes or mini-computers, which are shared by many users.
Phase
An angular or sinusoidal relationship between two alternating quantities of energy.
Phase Modulation
One of three basic methods (see also Amplitude and Frequency Modulation) of adding information to a sine wave signal in which its phase is varied to impose information on it.
Phase Shift
A change in the phase relationship between two alternating quantities. See Phase.
Photodetector (Receiver)
Converts light energy to electrical energy. The silicon photo diode is most commonly used for relatively fast speeds and good sensitivity in the 0.75 um to 0.95 um wavelength region. Avalanche photodiodes (APD) combine the detection of optical signals with internal amplification of photo-current. Internal gain is realized through avalanche multiplication of carriers in the junction region. The advantage in using an APD is its higher signal-to-noise ratio, especially at high bit rates (transmission speeds).
Photodiode
semiconductor diode that produces current in response to incident optical power and is used as a detector in fiber optics.
Photon
One quantum electromagnetical energy
PHY
Physical layer of the Fiber Distributed Data Interface (FDDI) standard. Also used to refer to the actual hardware used to implement the physical layer (PHY entity).
Physical Unit (PU)
Devices on an SNA network, such as controllers, that are physically rather than logically addressed by the host.
Pickup
Any device which is capable of transforming a measurable quantity of intelligence (such as sound) into relative electrical signals (e.g., a microphone) inductive or direct coupled.
Pico
Prefix meaning one-millionth of one-millionth.
Picofarad (pF)
A unit of capacitance used to designate capacitance unbalance of the two wires of a pair relative to ground. One picofarad equals one trillionth of a farad.
Pigtail
Optical fiber cable that has a connector installed on one end.
Pin
A conductor on a plug or connecting device/apparatus.
Pin Diode
A device used to convert optical signals to electrical signals in a receiver.
Plastic
High polymer substance, including both natural and synthetic products, yet excluding rubber that is capable of density flowing under heat and pressure.
Plasticizer
A chemical added to plastic to make them softer and more pliable.
Plenum
A return air space inside buildings through which environmental air is handled.
Plenum Cable
Cable specifically designed for use in a plenum. Plenum Cable has insulated conductors often jacketed to give them low flame-spread and low smoke-producing properties.
Plug
A device used for connecting conductors to a jack. It is typically used on one or both ends of equipment cords or on wiring for interconnects or cross-connects.
PMD
Physical medium dependent. Determines the specifications for transmitters and receivers, cables, connectors and bypass switches.
Point-to-Point Transmission
An uninterrupted connection between two pieces of equipment (link/channel).
Poke-Through Method
A ceiling distribution system method that involves drilling a hole through the floor from the ceiling space below and poking cables through to terminals. Not Recommended.
Polybutadene
A type of synthetic rubber often blended with other synthetic rubbers to improve their properties.
Polyethylene
A thermoplastic material having excellent electrical properties.
Polymer
A substance made of specific repeating chemical units or molecules. The term polymer is often used correctly or incorrectly, in place of plastic, rubber or elastomer.
Polypropylene
A thermoplastic similar to polyethylene but stiffer and having a higher softening temperature.
Polyurethane
Broad class of polymers noted for excellent abrasion and solvent resistance. Can be in solid or cellular form (formed/expanded).
Polyvinyl Chloride (PVC)
A multipurpose thermoplastic used for wire and cable insulation and jackets.
Polyvinylidene Difluoride (PVDF)
A fluoropolymer material that is resistant to heat and is widely used in the jackets of plenum cable.
Ports
Terminations in equipment systems at which various types of communication devices, switching equipment, and other devices are connected to the transmission network.
POTS
plain old telephone service
Potting
Sealing by filling with a substance to exclude moisture intrusion.
Power
The amount of EMF/energy per unit of time. Usually expressed in watts.
Power Arrestor
A protection device used on power lines to limit ground surge voltage due to lightning, while simultaneously interrupting power "follow-on" (the discharge of normal power).
Power/Communication 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 or Ceiling Drop Pole.
Power Loss
The difference between the total power delivered to a circuit, cable or device and the power delivered by that device to a load.
Power Ratio
The ratio of power appearing at the load to the input power, usually expressed in dB.
Preform
A glass structure from which an optical fiber waveguide may be drawn.
Prefusing
Fusing with a low current to clean the fiber end. Precedes fusion splicing.
Premises Distribution System (PDS)
The transmission network inside a building or group of buildings that connect various types of voice and data communication devices, switching equipment, and information management systems together, as well as to outside communications networks. It includes the cabling and connecting hardware components and facilities between the point where building wiring connects to the outside network lines, back to the voice and data terminals in the office or other work locations. The system consists of all the transmission media and electronics, administration points, connectors, adapters, jacks, plugs, and support hardware between the building’s side of the network interface and the terminal equipment required to make the system operational.
Premise Wiring/Structured Wiring (Premise Cabling/Structured Cabling)
The entire wiring system on the user’s premises used for transmission of voice, data and video.
Prewiring
Wiring installed before walls and ceilings are enclosed or finished, and in anticipation of future use or need. It is more cost effective to prewire all potential locations at the time of a major installation, rather than return on a repeated basis to keep adding locations one (or more) at a time.
Primary Coating
The plastic coating applied directly to the cladding surface of the fiber during manufacture to preserve the integrity of the surface.
Primary Power
Voltages >300V RMS to ground.
Primary Rate Interface (PRI)
ISDN standard interface comprising 23 "B"+1 "D" channel for North America, and 30 "B"+1 "D" Channel for Europe. See Basic Rate Interface (BRI) and Integrated Services Digital Network (ISDN).
Primary Ring
One of two rings of the dual counter-rotating ring architecture. This ring is designated as the primary ring because it is the default ring that single-media access control (SMAC) stations connect to unless instructed to do otherwise.
Printed Circuit
A copper foil circuit formed on one or both faces of an insulating board to which circuit components are soldered. The copper foil pattern serves to connect components and is produced either by etching or plating.
Printer Emulation
A feature of 3270 emulation that makes the printer attached to a PC appear to be an IBM 3270 printer.
Private Branch Exchange (PBX) or Private Automatic Branch Exchange (PABX)
A private telephone switching system, usually located on a customer’s premises connecting a common group of lines from one or more central offices to provide service to a number of individual phones. Now used interchangeably with PABX (private automatic branch exchange).
Propagation Delay
Time required for a signal to pass from the input to the output of a device. See NVP.
Protector
Device used to limit damaging foreign voltages and currents on metallic telecommunications conductors and equipment.
Protector (Cable)
Cable protectors limit the voltage between the conductors and shield of a cable. Standard cable protectors are equipped with 6-mil carbon electrodes. Standard cable protectors limit voltages to 800V DC which may not address today’s low-voltage requirements.
Protector (Unit)
A device to protect against either overvoltage, overcurrent or both. The unit may contain carbon electrodes, gas tubes, solid state components, heat coils, fuses or a combination thereof. Units may be integrated or have plug-in/screw-in elements depending on the application and design. Used with, or in, protector blocks, protected terminals, connecting blocks and central office connectors as well as PABX and other devices/systems.
Protector Module
A device that limits voltage between telecommunications conductors and ground. The protector is equipped with 3 mil carbon electrodes or equivalent gas tubes. Typical line protectors limit voltage to 350V DC. See Protector (Cable).
Pseudo Random NRZ
A wave form of binary signals that may be used in a computer system. It is called NRZ, non-return to zero, because the voltage does not return to zero. Also, non return to zero, inverted (NRZI).
Public Data Network
A network established and operated for the specific purpose of providing data transmission services to the public through IXCs/IECs.
Public Switched Network
Any common carrier network that provides circuit switching between public users, such as the public interactive telephone network.
Pulling Tension
The amount of pull, measured in pounds or foot-pounds, placed on a cable during installation.
Pulse
A current or voltage which changes abruptly from one value to another and back to the original value in a finite length of time. Used to describe one particular variation in a series of wave motions.
Pulse Code Modulation
The most common method of representing an analog to digital signal, such as speech, by sampling at a regular rate and converting each sample to an equivalent digital code.
Pulse Spreading
The dispersion of an optical signal with time as it propagates through an optical fiber.
Punch Down
See Cut Down.
PVC
Polyvinyl chloride, widely used in cable sheaths/jackets and conduits.
QA/QC
Quality assurance/quality control. Should be clearly defined in contract terms and conditions.
QFLC
quad fiber loop converter (four T-1s)
Quad Fiber Cable
A type of fiber optic cable that has four single cables enclosed in an extruded jacket of polyvinyl chloride (PVC), with a rip cord for pulling back the jacket to access the fiber.
Quick Clip
An electrical contact used to provide an insulation displacement connection to telecommunications cables.
R
Symbol for resistance (ohms).
Raceway
Examples of raceways include, but are not limited to:
1. Conduit (rigid or flexible, metallic or nonmetallic) EMT, a thinwall electrical metallic tubing
2. Sleeves, slots, cores or auxiliary channels (gutters)
3. Baseboard (concealed) systems
4. Underfloor systems. Cellular floor systems
5. Cable trays, troughs, ladder racking
6. Busways, surface raceways, lighting fixture raceways and latch duct, nonmetallic or metallic. There are other raceways/ pathways that may need to be considered.
*Note: Flexible metallic (flex) conduit should never be a consideration, recommendation or option for communications.
Rack
A vertical or horizontal open support, usually made of aluminum or steel, that is attached to a floor, ceiling or wall. Cables are laid in and fastened to the rack and connected to the equipment(s).
Radio Frequency
The frequencies in the electromagnetic spectrum that are used for radio communications.
Raised Floor Method
A floor distribution method in which square, steel or wood-laminated plates resting on aluminum locking pedestals are attached to the building floor. Also called access floor, since each plate can be removed for easy access to cables below.
Random Access Memory (RAM)
A semiconductor storage device in which data can be entered, read and erased. RAM is the fastest form of data storage and retrieval, however, the data is erased when the power is turned off.
Rayleigh
English physicist (1842-1919), nobel prize winner
Rayleigh Scattering
The scattering of light that results from small inhomogeneities in material density of composition.
RBOC (Regional Bell Operating Company)
One of the seven Bell operating companies that were formed during the divestiture of AT&T.
RCDD
Registered communications distribution designer. Certification program for telecommunications industry personnel planning to consult or design. Requires documented experience, knowledge and testing to obtain status.
Reactance
A measure of the combined effects of capacitance and inductance on an alternating current. The amount of such opposition varies with the frequency of the current. The reactance of a capacitor decreases with an increase in frequency; the opposite occurs with inductance.
Real Time
A form of information processing where output is generated nearly simultaneously with the corresponding input. Used mostly where the results of the computation are used to influence a process while it is occurring.
Receiver
An electronic fiber package that converts light energy to electrical energy in a fiber optic system.
Reflectance
Reflectance is the ratio of power reflected to the incident power at a connector junction or other component junction, usually measured in decibels or dB. Reflectance is stated as a negative value, e.g., -30 dB. A connector that has a better reflectance performance would be a -40 dB connector or a value less than -30 dB. The term return loss, back reflection and reflectivity are also used synonymously in the industry to describe device reflections, but stated as positive values.
Reflection
The change in direction (or return) of waves striking a surface. For example, electromagnetic energy reflections can occur at an impedance mismatch in a transmission line, causing standing waves.
Refractive Index
The ratio of light velocity in a vacuum to its velocity in the transmitting medium.
Refraction
The bending of a beam of light at an interface between two dissimilar media or a medium whose refractive index is a continuous function of position (graded index medium).
Regenerator
A device which restores a signal to its original undistorted quality, including amplitude, waveshape and timing.
REH
remote electronic hubs
Remote Terminal
A terminal that is physically removed from the host but connected to it by a communications link such as a phone line. Ex: distributed node, PABX.
Repeater
A device inserted at intervals along a circuit to boost and amplify a signal being transmitted. Repeater may also regenerate a digital signal - squaring it and cleaning it up - but not changing it. Regenerating the signal removes noise and thus reduces the likelihood of error.
Requirements Survey
The systematic study of a building or campus of buildings to determine the needs for voice and data telecommunications equipment and distribution media. This is normally done prior to designing the system for the site.
Resistance
The property of a conductor that determines the current produced by a given potential difference. It impedes the flow of current and results in the dissipation of power as heat. Resistance is measured in ohms.
Resonance
An ac circuit condition in which inductive and capacitive reactance interact to cause a minimum or maximum circuit impedance.
Response Time
The time it takes a system to react to a given input. The response includes the transmission time, the processing time, the time for searching records and the transmission time back to the originator.
Retractile Cord
A cord having specially treated insulation or jacket so it will retract like a spring. Retractibility may be added to all or part of a cord’s length.
Return Loss
Noise or interference caused by impedance discontinuities along the transmission line at various frequencies. Return loss is expressed in decibels.
RF
radio frequency
RFI
(a.) request for information. (b) radio frequency interference. A disturbance in the reception of signal transmission due to conflicting undesired signals, either through induction, radiation or, less frequently, unbalanced line conditions or poor circuit design. See EMI.
RFP
request for proposal
RFQ
request for quotation
RG/U
RG is the military designation for coaxial cable, and U stands for universal.
Ribbon Fiber Cable
A cable that contains one to 12 ribbons, with each ribbon having 12 fibers for a cable size range of 12 to 144 fibers. Ribbon fiber cables are designed for use in large distribution systems where small cable size and high pulling strength are important.
Ribbon Riser Cable
An optical fiber, nonconductive, riser (OFNR)-rated premises cable containing optical fibers possibly in ribbons.
Ring Circuit
Ring-shaped cable network with half of the circuits going in each direction so a cut at any point will still leave all locations with limited access to the central office.
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.
Ring In (RI)
Inward port of connecting multistation access units (MAUs).
Ring Out (RO)
Outward port of connecting multistation access units (MAUs).
Riser
The conduit or path between floors of a building into which telephone and other utility cables are placed to bring service from one floor to another.
Riser Backbone System
The part of a premises distribution system that includes a main cable route and structure for supporting the cable from an equipment room (often in the building basement) to the upper floors, or along the same floor, where it is terminated on a cross-connect in a riser telecommunications closet, at the network interface, or at distribution components of the campus backbone subsystem.
Riser Telecommunications Closet
The closet where riser backbone cable is terminated and cross-connected to either horizontal cable or to other riser backbone cable. The riser telecommunications closet houses cross-connect facilities, and may contain auxiliary power supplies for terminal equipment located at the user work area.
RMS
root mean square
Rope Strand
A conductor composed of groups of twisted strands.
Router
A router can be used to connect networks with similar protocols (802.5 Token Ring LANs) or dissimilar open system interconnect (OSI) model protocols (802.5 Token Ring LANs and X.25 packet switching networks). Routers are more sophisticated than bridges and can be used to prevent some of the speed mismatch, security and reliability problems that occur in large networks.
RS232-C
A set of standards specifying various electrical and physical characteristics for interfaces between computers, terminals and modems. The RS-232-C standard was developed by the Electronics Industries Association (EIA), and defines the mechanical and electrical characteristics for connecting DTE and DCE data communications devices. It defines what the interface does, circuit functions and their corresponding connector pin assignments. The standard applies to both synchronous and asynchronous binary data transmission. The traditional RS-232-C plug is functionally equivalent to CCITT V024/V.28.
RS-442 and RS-443
Both are EIA recommended standards for cable lengths that extend the RS-232-C 50 foot limit and describe the electrical characteristics of balanced-voltage and unbalanced-voltage digital interface circuits.
RS-449
An EIA recommended standard for the mechanical characteristics of two connectors (a 37-pin connector and a 9-pin connector). Designed for higher speeds not widely used yet.
Rubber (Wire Insulation)
A general term used to describe wire insulations made of thermosetting elastomers, such as natural or synthetic rubbers, neoprene, butyl rubber and others.
Satellite Cabinet
Surface-mounted or flush-type wall cabinets for housing circuit administration hardware. Satellite cabinets, like satellite telecommunications closets, supplement riser telecommunications closets by providing additional facilities for connecting horizontal cables from information outlets in user work areas. Sometimes referred to as a satellite location. No longer recommended terminology. See TC.
Satellite Telecommunications Closet
A walk-in or shallow wall closet that supplements a riser telecommunications closet by providing additional facilities for connecting riser backbone to horizontal cables from information outlets. Also referred to as a satellite location. No longer recommended terminology. See TC.
SBR
A copolymer of styrene and butadene. Also GR-S or Buna-S. Most commonly used type of synthetic rubber.
Scattering
A property of glass that causes light to deflect from the fiber and contributes to optical attenuation.
Schedule 40
PVC (polyvinyl chloride) conduit typically used for underground entrance facilities. Refer to local governing codes and conditions.
SDIP
standardized dedicated inside plant
Secondary Power
Power operating at <300V RMS to ground. See Primary Power.
Secondary Protection
Supplemental. Auxiliary. A secondary protector installed in series with the indoor communications cable between the primary protector and the equipment. The secondary protector must provide overcurrent protection which will safely fuse at currents less than the current carrying capacity of listed:
Indoor communications wire and cable; telephone set line cords, patch cords, etc.; communications terminal equipment having ports for external wire line circuits.
Secondary Ring
One of the two rings of the dual counter-rotating ring architecture. Designated the secondary ring because single-media access control (SMAC) stations connect in the default mode to the primary ring. The secondary ring is used for data transport by dual-media access control (DMAC) stations, SMAC stations commanded to move to the secondary ring, or in the case of ring wraps, by all stations.
Semiconductor
In cable industry terminology, a material possessing electrical conductivity that falls somewhere between that of conductors and insulators. Usually made by adding carbon particles to an insulator. Not the same as semiconductor materials such as silicon, germanium, etc., used for making transistors and diodes.
Sensitivity
For a fiber optic receiver, the minimum optical power required to acheive a specified level of performance, such as BER.
Separator
Pertaining to wire and cable, a layer of insulating material such as textile, paper, etc., which is placed between a conductor and its dielectric, between a cable jacket and the components it covers, or between various components of a multiple-conductor cable. It can be utilized to improve stripping qualities, flexibility, or can offer additional mechanical or electrical protection to the components it separates.
Serial Transmission
A method of transmission in which data is sent one bit at a time, in contrast with a parallel transmission, in which multiple bits (usually eight) are sent simultaneously.
Series Circuit
A circuit in which the components are arranged end to end to form a single path for current.
Service Clearance
The space encompassing the equipment, or unit, which is required to permit proper working room for operating, inspecting and servicing equipment. This space should adequately allow:
• Doors to be fully opened.
• Component drawers to be pulled out, or racks opened.
• Allows safe work operations. Min. 36".
Session
A logical connection with a host system. The session begins when you establish the communications link and ends when you terminate emulation and return to DOS.
Sheath
A common term for the jacketing of twisted pairs in multipair cable.
Sheave
The grooved wheel or pulley used to assist in pulling cable through a bend in the routing; especially used in underground installations between manholes.
Shield
The metallic layer that surrounds insulated conductors in shielded cable. The shield may be the metallic sheath of the cable or the metallic layer inside a sheath.
Shield Coverage
The physical area of a circuit or cable actually covered by shielding material often expressed as a percentage.
Shield Effectiveness
The relative ability of a shield to screen out undesirable interference. Frequently confused with the term shield coverage.
Shielding
A metallic layer used to reduce EMI, RFI, noise, emissions or absorption. Also, the reduction of undesirable effects on circuits caused by electrostatic fields (FED-STD-1037A).
Signal
Any visible or audible indication which can convey information. Also, the information conveyed through a communications system.
Signal to Noise Ratio
The ratio of the received optical power, with fill signal averaging, divided by the noise floor for the detector.
Silicone
General Electric trademark for a material made from silicone and oxygen. Can be in thermosetting elastomer or liquid form. The thermosetting elastomer form is noted for high heat resistance.
Simplex Transmission
Data transmission over a circuit capable of transmitting in one preassigned direction only.
Single-Attached Stations (SAS)
A station type defined in the fiber distributed data interface (FDDI) stations management (SMT) standard, an SAS has a single physical medium dependent/physical layer (PMD/PHY) interface. SASs are less expensive than dual-attached stations (DASs) because of other reduced electronics and optics, but they do not directly gain the reliability advantages of dual rings.
Single-ended
Unbalanced, such as grounding one side of a circuit or transmission line.
Single-Fiber Cable
A plastic-coated fiber surrounded by an extruded layer of polyvinyl chloride (PVC), encased in a synthetic strengthening material, and enclosed in a PVC sheath.
Single Media Access Control (SMAC)
Fiber distributed data interface (FDDI) stations with a single media access control (MAC) entity. SMAC stations can logically send and receive data over a single ring of the dual-ring architecture at any given time. SMAC stations have access to 100 Mbps bandwidth from the network.
Singlemode Fiber
A fiber wave guide in which only one mode will propagate. The fiber has a very small core diameter of approximately 8 um. It permits signal transmission at extremely high bandwidths and is generally used with laser diodes.
Sintering
Melting of powder into solid state
Sinusoidal
Varying in proportion to the sine of an angle or time function. Ordinary alternating current is sinusoidal.
Skew Rays
A ray that does not intersect the fiber axis. Generally, a light ray that enters the fiber core at a very high angle.
Skin Effect
The tendency of alternating current to travel on the surface of a conductor as its frequency increases.
Slab on Grade
A concrete floor place directly on the soil without a basement or crawl space.
SLC
subscriber loop carrier or subscriber line concentrator
Sleeve
A metallic section of conduit (typ.) that extends above the floor line (after coring) at least one (1) inch, and extends into the space below as required by local fire codes. Review local codes to determine exact dimensions and firestopping practices.
Slot
An opening, usually rectangular (typ. 6" x 9"), through floors, ceilings or walls that accommodate placement of cable and wiring. See Firestopping. Refer to NFPA Articles, and local ordinances.
SMA 905/906 (Subminiature Type A)
A threaded type fiber optic connector. The 905 version is a straight ferrule design, whereas the 906 is stepped ferrule design. See EIA/TIA standards for connector 568SC.
SNA
System network architecture is a synchronous communications protocol designed by IBM that provides an interface between components in a computer network.
Sneak Current
A foreign current flowing to ground through terminal wiring and equipment that is driven by a voltage that is too low to cause a protector to operate.
Sneak Current Protection
The use of devices to protect against sneak currents either by interrupting the current (fuses) or grounding the conductor (heat coils).
SONET
Synchronous optical network; provides broadband connectivity for optical networks on a global scale.
Source
The device (usually LED or laser) used to convert an electrical information-carrying signal into a corresponding optical signal for transmission by an optical fiber.
Source Routing
A bridge uses source routing when the route to be followed is carried within each frame by the source stations. The source station acquires and maintains information by a search process, allowing parallel bridges to exist and to share traffic between the same two rings.
Spectral Bandwidth
Frequencies that exist in a continuous range and have a common characteristic. A spectrum may be inclusive of many spectrums (e.g. electromagnetic radiation spectrum includes the light spectrum, radio spectrum, infrared spectrum, etc.).
Speed of Light (c)
186,000+ mi. per second. See NVP.
Splice
The physical joining of two or more copper conductors or optical fibers to form a continuous circuit/conductor.
Splined Ceilings (Variation of False Ceilings)
A ceiling construction method where ceiling tiles are usually 12 in. x 12 in. and are lipped and locked together using runners or T-bars, and thin strips of metal called splines. Cable is run in the area above the tiles. Aka: "Locktile" ceilings.
Splice Closure
A container used to organize and protect splice trays. Typically used in outside plant environments.
Splice Tray
A container used to secure, organize and protect spliced fibers.
Stabilized Light Source
An LED or laser diode that emits light with a controlled and constant spectral width, central wavelength, and peak power with respect to time and temperature.
Stalpeth
Steel-aluminum-polyethylene, the primary sheath for underground cable.
Standard Protection
Also, primary protection. the minimum basic protection required on all exposed facilities to comply with NEC requirements.
Standing Wave Ratio (SWR)
A ratio of the maximum amplitude to the minimum amplitude of a standing wave stated in current or voltage amplitudes.
Star Topology
A network interconnection scheme in which one central location has links to all other nodes, which have no direct connections to each other. See examples in workbook.
Static Charge
An electrical charge that is bound to an object. An unmoving electrical charge.
Station Field
The field used in telecommunications closets or equipment rooms to connect horizontal cabling to stations via work area outlets. Station fields are blue.
Station Management (SMT)
The portion of the fiber distributed data interface (FDDI) standard that specifies ring monitoring, ring recovery, logical topologies and administration of station entities.
Stay Cord
A component of a cable, usually of high tensile strength, used to anchor the cable ends at their points of termination and keep any pull on the cable from being transferred to the electrical conductors.
Step-Index Fiber
An optical fiber in which the core is of a uniform refractive index with a sharp decrease in the index of refraction at the core/cladding interface.
STP
Shielded twisted pair typically (today) refers to 150 ohm, 22 AWG, 2 pair STP-A. See EIA/TIA 568A.
Strain Gauge
A device for determining the amount of strain (change in dimensions) when a stress is applied.
Straight-Tip (ST) Connector
(Orig. AT&T). A fiber optic connector used to join single fibers together at interconnects or to connect them to fiber optic cross-connects. See EIA/TIA 568SC recommended standard connector.
Stranded Cable
A strong woven-steel cable used to support cable in aerial distribution systems. The cable is lashed to the stranded cable during installation.
Strength Member
That part of a fiber optic cable composed of aramid yarn, steel strands or Fiberglas filaments that increase the tensile strength of the cable.
Stub Cable
A short cable (usually 25 ft. or less) that extends from a cable terminal, protector or block and is used to splice incoming cable connections to such devices.
Subminiature D Connector
A family of multipin data connectors used in RS-232-C communications. The connectors are available in 9, 15, 25 and 37 pin configurations. Sometimes referred to as DB9, DB15, DB25 and DB37 connectors respectively.
Support Hardware
The racks, clamps, cabinets, brackets, trays and other equipment that provides the physical means to attach the transmission media and connecting hardware to walls and ceilings, or in outside plant, ducts, manholes, vaults, poles, pullboxes, etc.
Surge
A temporary and relatively large increase in the voltage or current in an electric circuit or cable. Also called transient.
Surge Suppression
The process by which transient voltage (surges) are prevented from reaching sensitive electronic equipment.
Surface Raceway
A cable distribution method in which channels containing cables are run along or within the baseboards of a building.
Suspended Ceilings
A ceiling construction method where ceiling tiles are suspended by wires and T-bar. Cable is run in the area above the tiles. Aka: false ceilings.
Sweep-test
Pertaining to cable, the frequency response is verified by generating an RF signal whose frequency is swept repeatedly through a given frequency range at a rapid constant rate. The cable response is observed on an oscilloscope. The structural return loss sweep-test measures the magnitude of internal cable reflections.
Synchronous Data Link Control (SDLC)
The protocol IBM defined for synchronous data communications within SNA networks.
Synchronous Transmission
Transmission in which the data characters and bits are transmitted at a fixed rate with the transmitter and receiver being synchronized. Compare with Asynchronous Transmission.
System-Common Equipment
The equipment on premises that provide functions common to terminal devices such as telephone, data terminals, integrated workstation terminal and personal computers. Typically, the system-common equipment is the private automatic branch exchange (PABX) switch, data packet switch or central host computer.
T1
A digital transmission link with 1.544 Mbps bandwidth. T1 operates on two twisted pairs and can handle 24 voice channels, each digitized at 64 Kbps. More voice channels are available with advanced digital encoding techniques.
T1 Carrier
The digital transmission system which transmits data at 1.544 Mbps. See T1.
Tap
In communications, tap is an electrical connection permitting signals to be transmitted onto or off a bus. The link between the bus and the drop cable that connects the workstation. In power, a tap is an intermediate point in an electric circuit where a connection may be made.
Telecommunications
The transmission and reception of electrical or optical signals by copper wire, optical fiber or electromagnetic means. Encompasses all forms of transmitted intelligence, wire or wireless.
Telecommunications Closet (TC)
A space (formerly known as floor closet, IDF, satellite closet or other terms), in a building that is set aside to provide a safe, secure and environmentally suitable area for the installation of cables, wires, telecommunications equipment and/or termination and administration systems.
Telecommunications Service Entrance
The point where regulated telecommunications cables enter the building or property. See Entrance Facility.
Terminal
A device that provides a user interface to the host.
Terminal Block
An assembly, premanufactured to accept 22-26 AWG conductors, allowing termination and cross-connect administration, test points and/or fusing and protection where required.
TFE
Tetrafluoroethylene. A thermoplastic material proven to have excellent electrical insulating properties with chemical and heat resistance.
Thermal Rating
The temperature range in which a material will perform its function without undue degradation.
Thermoplastic
A plastic material that softens and flows when heated and becomes firm when cooled. This process can be repeated.
Thermoset/Thermosetting
A plastic material that is crosslinked by a heating process known as curing. Once cured, thermosets cannot be reshaped.
Thin Ethernet
An Ethernet LAN or IEEE 802.3 LAN which uses smaller diameter coaxial cable than standard Ethernet. Thinnet, cheapnet, etc.
TIA
Telecommunications Industry Association.
TIC
Token Ring Interface Coupler - A device that provides the connection between a host computer or front-end processor and a Token Ring LAN.
Tight-Buffered Cable
Type of cable construction whereby each glass fiber is tightly buffered by a protective thermoplastic coating to a diameter of 900 micrometers. Increased buffering provides ease of handling and connectorization.
Time Division Multiplexing (TDM)
A technique for combining multiple signals on a single circuit by interleaving bits or bytes of data from successive channels.
Timesharing
A method of computer operation that allows many users to use one computer. Due to the power and speed of the computer, it appears as though the users are served simultaneously, when in fact they are being served in sequence.
Tinsel
A type of electrical conductor comprised of a number of tiny threads, each thread having a fine, flat ribbon of copper or closely spiraled about it. Used for small size cables requiring flexibility and extra-long life.
Tip Conductor
A telephony term used to describe the positive conductor of a pair. This term was originally coined from its position as the first (tip) conductor of a tip-ring-sleeve switchboard plug.
TNC
A threaded connector used to terminate coaxial cables. TNC is an acronym for threaded Neill-Concelman.
Token Passing
A special data sequence that is continuously sent around the ring. The term token represents permission to transmit from one station to its downstream neighbor.
Token Ring
A baseband LAN access method with a ring topology supporting a four- to 16-Mbps data rate. Network access is controlled by passing a token to attached devices. Only the device in possession of the token can communicate over the network at one time.
Topology
The physical or logical configuration of a local area network (star, ring, bus). Used in telecommunications to describe the ways in which different facilities and services are cabled, and how the addition of new devices can most readily be accomplished (prewired).
Transceiver
A single device capable of both transmitting and receiving information.
Transducer
A device for converting mechanical energy to electrical energy.
Transfer Impedance
For a specified cable length, transfer impedance relates a current on one surface of a shield to the voltage drop generated by this current on the opposite surface of the shield. Transfer impedance is used to determine shield effectiveness against both ingress and egress of interfering signals. Cable shields are normally designed to reduce the transfer of interference-hence, shields with lower transfer impedance are more effective than shields with higher transfer impedance.
Transient
An abrupt change in voltage, of short duration, which may cause signal impairments, loss of memory or physical damage to equipment. See Surge.
Transition Point (TP)
An enclosure used to house the transition connection between flat undercarpet cabling and the traditional round cable feeding from the equipment closet.
Transmission Distance
The actual length of the path from the transmitter of one node to the receiver of the next downstream node. The maximum transmission distance is determined by the maximum signal loss (attenuation limit) that can be withstood between any transmitter and receiver.
Transmission Electronics
Any of the various devices used with different transmission media to convert from one transmission method to another. Transmission electronics may typically include multiplexing equipment and asynchronous data units (ADUs).
Transmission Line
An arrangement of two or more conductors or an optical fiber used to transfer signal energy from one location to another.
Transmission Loss
The reduction in power between any two points in a telecommunications system.
Transmission Media
The various types of copper wire and fiber optic cable used for transmitting voice, data or video signals.
Transmitter (optical fiber)
The electronic package that converts electrical energy to light energy in a fiber optic system, laser or LED.
Transport Control Protocol/Internet Protocol (TCP/IP)
A common network layer and transport layer data networking protocol.
Triboelectric Noise
Noise generated in a shielded cable due to variations in capacitance between the shield and conductor as the cable is flexed.
Trunk
Typically, a communication link between two switching systems. The term switching includes equipment in a central office (of the telephone company) and PABXs. A tie trunk connects PABXs. Central office trunks connect a PABX to the switching system at the central office and/or link other central offices together.
Turn-Key
A contractual arrangement in which one party designs and installs a system and turns over, in its entirety, to another party who will operate the system, after acceptance.
Twinaxial Cable
Two insulated conductors inside a common insulator, covered by a metallic shield and enclosed in a cable sheath. See Coaxial.
Twin-lead
A transmission line having two parallel conductors separated by insulating material. Line impedance is determined by the diameter and spacing of the conductors and the insulating material is usually 300 ohms for television receiving antennas. Aka: flat lead.
Twisted Pair
Two or more insulated wires twisted together. The twists, or lays, are varied in length to reduce the potential for signal interference between pairs. In cables greater than 25 pair, the twisted pairs are grouped and bound together in a common binder group. Twisted pair is the most common type of transmission media. Formerly referred to as direct inside wire (DIW). See Unshielded Twisted Pair (UTP).
Two-Wire Circuit
A circuit in which information signals in both directions are carried by the same two-wire path or loop.
UHF
Ultrahigh frequency. The spectrum extending from 300 to 3000 MHz as designated by the Federal Communications Commission.
UL Approved
Tested and approved by the Underwriters Laboratories Inc.
Unbalanced Circuit
A two-wire circuit with legs which differ from one another in resistance, capacity to earth or to other conductors.
Unbalanced Line
A transmission line in which voltages on the two conductors are unequal with respect to ground (e.g., a coaxial cable).
Undercarpet Wiring
A cable distribution method which uses flat cables placed beneath carpeting to provide voice, data video and power services to open office workstations. Difficult to install, administer or troubleshoot.
Underfloor Duct Method
A floor distribution method using a series of metal distribution channels, often embedded in concrete, for placing cables. This method uses one or two levels, depending on the complexity of the system. Sometimes referred to as underfloor raceways.
Underground Cable
Not "direct buried" but in support structures beneath the surface of the earth as in conduit, duct, ductbanks or other approved structures that isolate the cable from direct contact with earth and/or foreign power/EMI/RFI influences. Considered exposed to elements such as lightning, commercial power "hits", etc. (FED-STD 1 037A).
Underground Distribution Method
The method of running cable underground between buildings in campus systems by going through buried conduits.
Underwriters Laboratories (UL)
A private testing laboratory concerned with electrical and fire hazards of equipment.
Uniform Service Order Code (USOC)
Bell System term used on Universal System service orders and to denote varying pin configurations on registered jacks (RJs).
Unilay
A conductor with more than one layer of helically laid wires with the direction of lay and length of lay the same for all layers.
Unshielded Twisted Pair (UTP)
Copper cable with no foil or metallic/braid shielding, capable of high-speed voice and data transmission. Techniques exist to address the signal impairments due to the transmission characteristics of copper media and to limit radiated emissions. Standard predominant telecommunications media. See UTP-categories.
UTP-Categories
Category One - Intended for basic communications power limited circuit cable. There is no performance criteria specified in EIA/TIA 568A (UL Level One.)
Category Two - Low performance UTP. Typical applications include voice and low-speed data (IBM Type 3.) Not specified in 568A (UL Level Two.)
Category Three - Applies to UTP cables and associated connecting hardware with transmission characteristics up to 16 MHz. Typical applications include ARCNet 2.5 Mbps, 4 Mbps Token Ring, 10BASE-T and 100BASE-VG
Category Four - Applies to UTP cables and associated connecting hardware with transmission characteristics up to 20 MHz. Typical applications include 16 Mbps Token Ring and low loss 10BASE-T.
Category Five - Applies to UTP cables and associated connecting hardware with transmission characteristics up to 100 MHz (155 Mbps). Typical applications include 16 Mbps Token Ring, TP-PMD and CDDI and, of course, other (future) ATM.
VA
Volt-ampere. A designation of power in terms of voltage and current.
Value Added Network (VAN)
A data communications network leased from a common carrier with extra equipment, such as an interface computer with a database storage designed to provide additional services.
Velocity of Propagation, also Nominal Velocity of Propagation (NVP)
The transmission speed of electrical energy in a length of cable compared to the speed of light in free space (vacuum). Usually expressed as a percentage, e.g. .65c, .70c, etc.
VHF
Very high frequency. The spectrum extending from 30 to 300 MHz as designated by the Federal Communications Commission.
Video
Pertaining to visual information in an integrated system.
Video Display Terminal (VDT)
A display screen terminal that permits the viewing of text or graphics for operator manipulation. A cathode ray tube (CRT) terminal.
VLF
Very low frequency. The spectrum extending from 10 to 30 KHz, as designated by the Federal Communications Commission.
Voice Channel
A transmission channel usually limited to the bandwidth of the human voice (300 - 3400 Hz).
Voice Grade Line
A communications channel which can transmit and receive voice frequencies (300 - 3400 Hz).
Volt
The standard unit of electromotive force or electrical pressure. One volt (1 V) is the amount of pressure that will cause one ampere (1 A) of current to flow through one ohm of resistance.
Voltage
Electrical potential or electromotive force (EMF) expressed in volts.
Voltage Drop
The voltage developed across a component or conductor by the current flow through the resistance or impedance of the component or conductor.
VSB
vault splice box
Wangnet
Wang Laboratories’ proprietary broadband local area network.
Watt (W)
A unit of electrical power. One watt is equivalent to the power represented by one ampere of current with a pressure of one volt in a dc circuit, or to one joule (1 J) per second.
Wave Form
A graphical representation of a varying electrical quantity. Usually, time is represented on the horizontal axis, and the current or voltage value is represented on the vertical axis.
Wavelength
The physical distance of one electromagnetic wave cycle, or the distance between successive peaks of a wave.
Wavelength Division Multiplexers
Passive fiber optic components which combine or separate optical channels.
Webbed Conductors
The manufacturing process that physically binds the conductor insulation of the wire pairs of an unshielded twisted pair cable.
WCE
wall mount cable enclosure
White Field
The field used in the telecommunications closet or equipment room to terminate cables that connect first level backbone cables.
Wide Area Network (WAN)
Any physical network technology that spans large geographic distances through telco facilities or IECs. WANs usually operate at slower speeds than local area networks (LANs).
Wideband
A communications channel or medium having a bandwidth sufficient to carry multiple voice/video or data signals simultaneously. Also see Broadband.
Winch
A powerful machine for pulling heavy weights. It has a rotating drum around which a pulling cable is coiled.
Wiring Block
A molded plastic block that is designed in various pair configurations to terminate cable pairs and establish pair locations on connector systems. See Terminal Block.
Wiring Closet
See Telecommunications Closet.
Work Area Cable (Line Cord)
A cable assembly used to connect equipment to the telecommunications outlet in the work area. Max. 10 ft. (EIA/TIA).
Work Area Outlet (WAO) aka: Workstation
In general, a workstation is any designated location where constructive activities occurs. In communications, a workstation is an input/output device at which a user can send data to or receive data from a device for the purpose of performing a job. Usually a personal computer or a terminal. WAOs are considered to include voice, data (LAN), video or other applications. See definition for Telecommunications. Reference EIA/TIA 568A.
Wrap
A mechanism in the fiber distributed data interface (FDDI) standard by which the primary and secondary ring are joined by a station wrapping the primary input onto the secondary output (or vice versa). Through automatic failure detection mechanisms, downstream and upstream neighbors can identify faults and wrap away from the fault. The wrap results in an insulation of the fault, and the dual rings are converted into a single continuous ring until the fault is removed and the neighbors unwrap.
X
(a) Symbol for reactance, or (b) on floor plans, denotes a cross-connect location.
X.21
CCITT Standard defining the interface specifications between DTE and DCE for synchronous operation on public data networks, using a 15 pin connector (DB15).
X.25
A communication architecture developed by the International Telegraph and Telephone Consultative Committee (CCITT).
Zero-Dispersion Wavelength
Wavelength at which the chromatic dispersion of an optical fiber is zero. Occurs when waveguide dispersion cancels out material dispersion.
Zone Method
A ceiling distribution method in which serving areas are divided into sections or zones. Cable is then run to the center of each zone to serve the information outlets nearby. Variations of Star.
Zone of Protection
An area provided by a grounded vertical rod or mast, and creates a surface of a hypothetical sphere of 50 meters (54.68 yds.) that touches the aerial rod and earth tangentially. The surface is concave upward. See NFPA-78. Also referred to as cone of protection.