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Cable and Wire Glossary

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A

A  - Common abbreviation for ampere (see AMPERE).


A/D (analog/digital) converter  - A circuit device that converts analog signals to digital signals.



AAAC  - All-aluminum alloy conductor. A special high-strength aluminum alloy.



AAR  - American Association of Railroads.



AB switch  - A cable switch capable of switching one cable to one of two branch cables, A or B.



Abrasion resistance  - Ability to resist surface wear.



Absorption  - Physical phenomenon that attenuates light traveling in fibers by converting it into heat, thereby raising the fiber's temperature. Absorption results from impurities and defects in the glass structure.



AC  - 1. Alternating current. 2. A UL cable type (armored cable) with flexible metal tape armor.



ACAR  - Aluminum conductor, aluminum-reinforced cable. Used in overhead transmission and distribution.



Accelerated aging  - A test that duplicates long time environmental conditions in a relatively short time.



Accelerated life test  - A test in which a cable is subjected to extreme conditions to determine the life of a cable.



Acceptance test  - Made to demonstrate the degree of compliance with specified requirements.



Access group  - In LAN technology, all stations have identical rights to make use of computer, network or data PABX resources.



Access line  - The connection between a subscriber's facility and a public network-either a PDN, public switched network or public telephone network. Also, see LOCAL LINE.



Access method - 1. In IBM environments, a host program that manages the movement of data between the main storage and an input/output device of a computer system; BUAM, TCAM, VTAM are common data communications access methods. 2. In LAN technology, a means to allow stations to gain access to - to make use of - the network's transmission medium; classified as shared access, which is further divided into explicit access or contended access on discrete access method.



Access unit  - In the IBM token-ring network, a wiring concentrator.



ACCR  - Aluminum conductor, composite reinforced aerial cable. Contains a ceramic strength member to reduce sag at high temperatures (up to 210°C).



ACR (attenuation to crosstalk ratio) - The relationship between a signal's attenuation and near-end crosstalk (NEXT) levels expressed in decibels. ACR=usable bandwidth.



ACRF  - Attenuation to crosstalk ratio far-end. Communications cable specification. See ELFEXT.



ACSR  - Aluminum conductor, steel reinforced. A bare composite of aluminum and steel wires, usually aluminum around steel.



ACSR/AW  - Aluminum conductor, steel reinforced using aluminum clad steel wire.



ACSR/AZ  - Aluminum conductor, steel reinforced using aluminum coated steel wire.



ACSR/GA  - Aluminum conductor, steel reinforced using Class A zinc-coated steel wire.



ACSR/GB  - Aluminum conductor, steel reinforced using Class B zinc-coated steel wire.



ACSR/GC  - Aluminum conductor, steel reinforced, using Class C zinc-coated steel wire.



ACSS  - Aluminum conductor steel supported. This transmission line has fully annealed aluminum for better sag and high-temperature performance than ACSR.



Active converter - A device that converts one communication signaling standard to another (e.g., 10BASE-T to RS-232). Active converters require separate AC power sources.



Active device  - Any electronic device that is supplied activating power, normally from an external source. An amplifier is a typical active device.



Adapter  - A device that enables different sizes or types of plugs to mate with one another, provides for the rearrangement of leads, allows large cables with numerous wires to fan out into smaller groups of wires, or makes interconnections between cables. In fiber optics, it joins two connectors of the same (or different) types.



Adaptive equalizer  - An equalizer that adjusts to meet varying line conditions; most operate automatically.



Address  - The digital location of a terminal, a peripheral device, a node, or any other unit or component in a network, or process control system.



Adhesive-bonded - Cables bonded by adding an adhesive coating to the surface of the cable components, then joining and curing the adhesive to form a cable. See BONDED CABLE.



Administration subsystem - The part of a premises distribution system that includes the distribution hardware and components for adding or rearranging circuits. These components include cross-connects, interconnects and their associated patch cords and plugs.



Admittance  - A measure of how easily alternating current flows in a circuit. Admittance is the reciprocal of impedance. It is expressed in mhos.



ADP  - Automatic data processing.



ADPCM (adaptive differential pulse code modulation) - An encoding technique standardized by the CCITT that allows an analog voice conversation to be carried within a 32 kbps digital channel. Three or four bits are used to describe each sample, which represents the difference between two adjacent samples. Sampling is done 8,000 times per second.



ADU  - Asynchronous data unit.



AEIC  - Association of Edison Illuminating Companies. Electric energy industry association.



AERIAL CABLE  - A cable suspended in the air on poles or other overhead structure.



AES (advanced encryption standard)  - A type of cryptographic algorithm used to protect sensitive (unclassified) information. Usually seen in conjunction with wireless applications.



AF  - Audio frequency.



AFCI  - Arc fault circuit interrupter. A protective device that detects arcing and breaks the circuit to protect the load when arcing is detected.



AGC  - Automatic gain control. A feedback circuit that automatically adjusts the system gain.



Aging  - The irreversible change of material properties after exposure to an environment for an interval of time.



AIA  - Aluminum interlocked armor. A type of cable sheath consisting of interlocked pieces of aluminum armor.



Air core cable  - A cable in which the interstices in the cable core are not filled with a moisture barrier.



Air spaced coax  - A coaxial cable in which air is basically the dielectric material. The conductor may be centered by means of a spirally wound synthetic filament, beads or braided filaments. This construction is also referred to as an air dielectric.



Aircraft wire  - An electrical wire primarily designed for the extreme conditions (temperature, altitude, solvents, fuels, etc.) of airborne equipment.



AIT (advanced intelligent tape)  - A type (format) of recording tape.



AL  - Aluminum.



Alarming  - The ability of CCTV equipment to respond to an input signal, normally a simple contact closure. The response varies depending on equipment type.



Alloy  - A substance having metallic properties and being composed of an elemental metal and one or more chemical elements.



ALPETH  - Telecommunications cable employing a corrugated aluminum shield and an outer polyethylene jacket.



ALS  - Aluminum sheathed. A type of cable consisting of insulated conductors enclosed in a continuous, closely fitting aluminum tube. Listed type in the Canadian Electric Code.



Alternating current  - Electric current that periodically reverses direction. Alternating current is generally abbreviated AC.



AM (amplitude modulation)  - A method of adding information to an electronic signal where the height (amplitude) of the wave is changed to convey the added information.



Ambient temperature  - The temperature of a cable group when there is no load on any cable of the group or on the duct bank containing the group.



Ambient  - Conditions existing at a test operation location prior to energizing of equipment (e.g., ambient temperature).



AMI (alternate mark inversion) - A T-1 line code.



Ampacity  - The current a device can carry within specified temperature limitations in a specified environment dependent upon a) temperature rating; b) power loss; and c) heat dissipation.



Ampere  - A standard unit of current. Designated as the amount of current that occurs when one volt of EMF is applied across one ohm of resistance. An ampere of current is produced by one coulomb of charge passing a point in one second.



Ampere-turn - The product of amperes times the number of turns in a coil.



Amplifier  - A device used to boost the strength of an electronic signal.



Amplitude distortion  - An unwanted change in signal amplitude, usually caused by nonlinear elements in the communications path.



Amplitude modulation (AM)  - A method of adding information to an electronic signal where the amplitude of the wave is changed to convey the added information.



Amplitude  - The maximum value of a varying wave form.



Analog loopback  - Technique for testing transmission equipment and devices. It isolates faults to the analog signal receiving or transmitting circuitry, where a device, such as a modem, echoes back a received (test) signal that is then compared with the original signal.



Analog  - Not digital. A continuously varying waveform.



Angle of view  - The angular range that can be focused within the image size. Small focal lengths give a wide angle of view, and large focal lengths give a narrow field of view.



ANI (automatic number identification)  - Provides the telephone number of an incoming call for various purposes.



Anneal  - To soften and relieve strains in any solid material, such as metal or glass, by heating to just below its melting point and then slowly cooling it. This also generally lowers the tensile strength of the material while improving its flex life.



Annealed wire  - See SOFT WIRE.



Annular ring  - An 8 mm (5/16 in.) wide black band printed at 2.5 m (8.2 ft.) intervals on standard Ethernet coaxial cable to identify locations at which transceivers may be connected.



Annular conductor  - A number of wires stranded in reversed concentric layers around a core.



Annunciator wire  - Usually single solid copper, sometimes twisted pair or triplexed for open wiring of bell circuits and other low-voltage systems.



ANSI (American National Standards Institute)  - A not-for-profit organization that publishes nationally recognized standards.



Antenna lead-in wire - Not coaxial; parallel twin lead construction, plastic jacketed with fixed 300-ohm impedance for connecting a remote antenna to a receiver.



Antenna rotor cable  - Multiconductor flat or round cable used to supply power to a motorized antenna and control wires for changing direction of rotation.



Antioxidant  - Retards or prevents degradation of materials exposed to oxygen (air).



Aperture  - The opening of a lens that controls the amount of light reaching the surface of the pickup device. The size of the aperture is controlled by the iris adjustment. By increasing the f-stop number (f1.4, f1.8, f2.8, etc.) less light is permitted to pass to the pickup device.



API (application programming interface)  - Defines the methods by which other software applications can access and/or control a given system.



Apparent power  - The product of the voltage and amperage (VA) in a system. Wiring must be sized to handle the apparent power, and utilities charge extra for loads that require large amounts of reactive power. For this reason, large industrial loads are often power factor corrected using large capacitors to prevent drawing the reactive power needed from the utility distribution system, instead drawing from the capacitors and presenting a less reactive load to the grid.



APPN (advanced peer-to-peer networking) - A System/46 feature that provides distributed processing through a set of services based on Node Type 2.1 network node and Logical Unit 6.2. These services include connectivity, directory, route selection, session activation and data transport and provide for distributed, dynamic node resource updates and intermediate, pass-through node capabilities.



Approved  - 1. Acceptable to the authority having legal enforcement. 2. Per OSHA: a product that has been tested to standards and found suitable for general application, subject to limitations outlined in the nationally recognized testing lab's listing.



Aramid yarn  - Strength elements that provide tensile strength, support and additional protection for fiber bundles. Kevlar is a brand name of aramid fiber.



Arc resistance  - The ability of a material to resist the action of a high-voltage electrical arc, usually stated in terms of the time required to render the material electrically conductive.



Architecture  - The manner in which a system (such as a network or a computer) or program is structured. See also CLOSED ARCHITECTURE, DISTRIBUTED ARCHITECTURE and OPEN ARCHITECTURE.



Arcnet (Attached Resource Computer Network)  - The Datapoint 2.5 Mbps local area network that was one of the first local area networks.



Armature  - 1. Rotating machinery: the member in which alternating voltage is generated. 2. Electromagnet: the member which is moved by magnetic force.



Armor  - Mechanical protector for cables; usually a helical winding of metal tape, formed so that each convolution locks mechanically upon the previous one (interlocked armor); may be a formed metal tube or a helical wrap of wires.



Armor-X - Southwire's trademark for CCW aluminum armor.



Array connector  - A connector that aligns and protects the 12 fibers from a ribbon fiber cable. A fanout array design can be used to connect ribbon fiber cables to non-ribbon cables.



Arrhenius plot  - A statistical method used to predict time-to-failure, based on a device's performance at different temperatures. One method for generating this plot is given in IEEE Standard 101.



AS/400  - Application Systems, IBM's midrange computer system that was originally designed to operate on twinax cable, may now also be implemented on unshielded twisted pair with the use of twinax baluns.



ASCII (American National Standard Code for Information Interchange)  - A seven bit plus parity code established by the American National Standards Institute to achieve compatibility among data services and consisting of 96 displayed upper and lower case characters and 32 nondisplayed control codes.



ASCII Terminal  - A terminal that uses ASCII; usually synonymous with asynchronous terminal and with dumb terminal.



ASIC  - An IC designed for specific applications, typically a gate array or a full custom chip.



ASIS (American Society of Industrial Security)  - A professional organization for the security industry.



Askarel  - Synthetic insulating oil that is nonflammable but very toxic. It has been replaced by silicone oils.



ASME  - The American Society of Mechanical Engineering, a not-for-profit professional organization.



ASP  - Telecommunications cable employing a corrugated aluminum shield (A), corrugated steel shield (S) and an outer polyethylene (P) jacket. Considered rodent-resistant and used primarily in underground applications.



Aspect ratio  - The ratio of the picture frame width to the picture frame height in standard TV systems. It is four units horizontal and over three units vertical.



Aspherical lens  - A lens designed with a nonspherical shape that refracts the light passing through it to either lower the lens aperture, so it passes more light or decrease barrel distortion on wide angle lenses.



ASTM (American Society for Testing and Materials)  - A group writing standards for testing materials and specifications for materials.



ASTM  - American Society for Testing and Materials. An organization that sets standards on various material tests for industry.



ASU (automatic switch unit)  - Provides automatic switching from one coaxial cable or network component to a redundant cable or network component in response to loss of signal on the primary cable or component.



ASYNC  - Asynchronous.



Asynchronous terminal  - A terminal that uses asynchronous transmission, usually synonymous with ASCII terminal and with dumb terminal.



Asynchronous  - Transmission in which each information character is individually synchronized, usually by means of start and stop elements. Also called start-stop transmission.



ATA (analog terminal adapter) - A device that converts an analog terminal, like a phone,to one that works on an ISDN line or Ethernet. (Analog to IP phone device is one example.)



ATDM (asynchronous time-division multiplexing) - A TDM that multiplexes asynchronous signalsby over-sampling; also infrequently used to mean a concentrator.



ATM (asynchronous transfer mode)  - A connection-type transmission mode carrying information organized into blocks (header plus information field); it is asynchronous in the sense that recurrence of blocks depends on the required or instantaneous bit rate. Statistical and deterministic values have been proposed that correspond respectively to the packet and circuit values defined for information transfer mode.



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. It is measured in decibels per unit length of cable.



Attenuation  - The decrease in magnitude of a wave as it travels through any transmitting medium, such as a cable or circuitry. Attenuation is measured as a ratio or as the logarithm of a ratio (decibel).



Audio frequency  - That range of frequencies lying within the range of human hearing: approximately 20 to 20,000 Hz.



Audio  - A term used to describe sounds within the range of human hearing. Also used to describe devices that are designed to operate within this range.



AUI (Attachment Unit Interface)  - The interface between the Ethernet/IEEE 802.3 controller and the baseband transceiver or broadband modem.



Auto white balance  - A feature on color camera that constantly monitors the light and adjusts its color to maintain white areas.



Automatic frequency control (AFC)  - An electronic circuit used whereby the frequency of an oscillator is automatically maintained within specified limits.



Automatic gain control (AGC)  - An electronic circuit where the gain of a signal is automatically adjusted as a function of its input or other specified parameter.



Automatic iris lens  - A lens in which the aperture automatically opens or closes to maintain proper light levels on the faceplate of the camera pickup device.



Automatic level control (ALC)  - A feature on auto iris lenses (also known as the peak/average control). Adjusting this control allows the auto iris circuitry to either take bright spots more into consideration (peak), bringing out detail in bright areas, or less into consideration (average) bringing out detail in shadows.



Auto-terminating - A feature where the equipment (e.g., monitor) automatically selects the correct termination depending on whether the video output BNC is connected.



AVD (alternate voice data) - Telephone lines that have been electronically treated to handle both voice and data signals. Typically used on leased overseas circuits to save money.



AWG (American Wire Gauge)  - A standard measurement in the determination of the physical size (diameter) of a conductor determined by its circular mil area. The gauge varies inversely with the actual wire diameter. The larger the gauge number, the smaller the wire.



AWM  - Appliance Wiring Material. A UL 758 designation for a type of wire.

B

B&S  - Brown and Sharpe wire gauge; same as AWG.


B8ZS (Binary Eight Zero Suppression)  - A method of converting eight consecutive zero bits into a recognizable, intentionally bipolar violation. The violation is converted back into eight zero bits at the receiving end. Equipment at both ends of the span must be compatible with B8ZS for proper operation, also called Binary Eight Zero Substitution.



Back focal distance  - The distance from the rear most portion of the lens to the image plane.



Back light compensation (BLC)  - A feature on newer CCD cameras that electronically compensates for high-background lighting to give detail that would normally be silhouetted.



Backbone - 1. In packet switched networks, the major transmission path for a PDN. 2. The trunk media of a multimedia LAN separated into sections by bridges, gateways or routers. 3. PDS terminology for that part of the distribution system, including both wire and fiber cables, which is often called riser or house distribution. The backbone does not include the interconnection cables that connect ISN equipment, such as packet controllers and concentrators, to cross-connects or interconnects.



Backbone drop  - A network drop that is connected directly to the backbone segment. Backbone network - The network whose primary function is to forward network data grams between the other networks in the extended LAN.



Backbone network - The network whose primary function is to forward network data grams between The other networks in The extended LAN.



Backbone segment  - The Ethernet segment whose primary function is to forward data grams between the other segments in the Ethernet in a single Ethernet LAN, See BRANCH SEGMENT.



Backbone subsystem  - The part of a premises distribution system that includes the main cable route and the facilities for supporting the cable. The riser subsystem usually extends from an equipment room (often in a building's basement) to the upper floors in a multistory building or along the same floor in a single-story building. It is terminated on a cross-connect in a riser closet, at the network interface or on the distribution components of the campus subsystem.



Backfill  - The materials placed to fill an excavation, such as sand backfill in a trench.



Balanced circuit  - A circuit so arranged that the impressed voltages on each conductor of the pair are equal in magnitude but opposite in polarity with respect to ground.



Balanced line  - A cable having two identical conductors with the same electromagnetic characteristics in relation to other conductors and to ground.



Ballast  - A device designed to stabilize current flow.



Balun (BALanced/UNbalanced)  - A device that converts the impedance of one interface to the impedance of a second interface (usually coax to UTP).



Band Marking  - A continuous circumferential band applied to a conductor at regular intervals for identification.



Bandwidth  - The width of a communications channel, measured as frequency (in cycles per second or hertz). A channel's bandwidth is a major factor in determining how much information it can carry.



Bare conductor  - A conductor having no insulation or jacket.



Barrel connector  - A female connector for connecting two sections of coaxial cable.



Barrel-packed - Method of coiling wire into a drum for shipment.



BAS  - Building automation systems.



Baseband LAN  - A local area network employing baseband signaling.



Baseband modem  - A modem that does not modulate the signal before transmission thereby transmits the signal in its native form. Baseband signaling is the transmission of either digital or analog signals at their original frequencies.



Baseband network  - A type of network that carries a single channel of communications signals.



Baseband system  - A data transmission system in which information is encoded, multiplexed and transmitted without modulation of a carrier.



Baseband transmission  - Transmission method used for short distances (less than 10 miles). It uses a bandwidth whose lowest frequency is zero (DC level) for transmission of raw (carrier less) binary data. The transmission medium carries only one signal at a time.



Baseband  - A signaling technique in which the signal is transmitted in its original form and not changed by modulation (e.g., CCTV video X).



Battery backup unit  - An optional unit within an ISN packet controller that consists of three batteries connected in series. When AC power fails, the battery backup unit delivers 144 volts DC to the power supplies on each shelf of the packet controller.



Battery backup  - A battery that provides power when the main AC power fails.



Baud  - The number of signal (or state) changes in a carrier per second; also referred to as baud rate. The maximum baud rate of a modem is limited by the bandwidth of the phone line.



BCD (binary coded decimal)  - Group of binary digits representing decimal numbers, with each number allocated four binary digits. This system is widely used in telecommunications computer projects.



Bedding  - A layer of material applied to a cable immediately below the armoring.



Beldfoil  - Belden trademark for highly effective electrostatic shield using reinforced metallic foil.



Belt  - Layers of insulation on a conductor, or layers of jacket on a cable.



Belted-type cable - Multiple conductor cable having a layer of insulation over the assembled insulated conductors.



Bend loss  - A form of increased attenuation caused by (a) having an optical fiber curved around a restrictive radius of curvature or (b) micro bends caused by minute distortions in the fiber imposed by externally induced perturbations.



Bend radius - 1. The radius of curvature that a fiber can bend without breaking or causing excessive loss in fiber cable. 2. In copper cable, the minimum radius that a cable can be bent without the possibility of causing structural or electrical damage to the cable.



BEP  - Building entrance protection.



BER (bit error rate)  - The ratio of received bits that are in error, relative to a specific amount of bits received; usually expressed as a number referenced to a power of 10.



BERT (bit error rate tester)  - A network diagnostic instrument used to troubleshoot LANs.



BICSI  - Building Industry Consulting Service International.



BIL  - Basic impulse level. The crest value of a lightning impulse voltage of a specified wave shape that a high-voltage cable or termination is required to withstand under specified conditions.



Bimetallic wire  - A wire formed of two different metals joined together (not alloyed). It can include wire with a steel core, plated or coated wire.



Binary - 1. A half-duplex, character-oriented synchronous data communications protocol originated by IBM in 1964. 2. Digital system with two states: 1 and 0.



Binary encoded  - A signal consisting of two states such as on or off, high or low level, one or zero, or presence or absence of a signal.



Binder  - A tape or thread used for holding assembled cable components in place.



Binding post  - A device for clamping or holding electrical conductors in a rigid position.



Bipolar transmission  - Method of sending binary data in which negative and positive states alternate; used in digital transmission facilities such as DDS and T1, sometimes known as polar transmission.



Bipolar violation  - Two or more successive pulses having the same polarity in a bit stream.



Birdcage  - The undesired unwinding of a stranded cable.



BISDN (broadband ISDN)  - A form of the integrated services digital network (ISDN) that will carry digital transmission at rates equal to or greater than the T1 rate (1.544 megabits per second). BISDN standards packetize information (e.g., voice, data and video) into fixed-length cells for transmission over synchronous optical networks.



Bit stream  - A digital signal or series of pulses.



Bit  - Contraction of binary digit; fundamental unit of information expressed in digital form as the choice between only two states, for example, 0 or 1, or high or low, or on or off.



Bits per second (bps)  - The number of bits of data transmitted by a modem through a phone line in one second. To get the bps rate of a modem, multiply the number of signal changes per second (baud rate) by the number of bits of information carried by each change.



Black level  - The level of the video signal that corresponds to the maximum limits of the black areas of the picture.



Blanking  - The process of cutting off the electron beam in a camera pickup device or picture tube during the retrace period. It is a signal that is composed of recurrent pulses at line and field frequencies. It is intended primarily to make the retrace on a pickup device or picture tube invisible.



Blooming  - The halation and defocusing effect that occurs around the bright areas of the picture (highlight) whenever there is an increase in the brightness intensity.



BNC  - Common connector for coax. BNC is said to be short for Bayonet Neill-Concelman.



Bonded cable  - Cable consisting of pre-insulated conductors or multi-conductor components lay in parallel and bonded into a flat cable.



Bonded construction  - An insulation construction in which the glass braid and nylon jacket are bonded together.



Bonding  - The connecting together of all building and equipment electrical grounds to eliminate differences in electrical ground potential.



Booster  - A device inserted into a line (or cable) to increase the voltage. Boosting generators are also used to raise the level of a DC line. Transformers are usually employed to boost AC voltages. The term booster is also applied to antenna preamplifiers.



Boot  - 1. Protective coating over a cable, wire or connector in addition to the normal jacketing or insulation. 2. A form placed around the wire termination of a multi-contact connector to contain the liquid potting compound before it hardens.



Border light candle  - Same as stage cable but more than two conductors. Type SO cable is often used.



Bore hole cable  - Power and/or communications cable suspended down a vertically drilled hole to equipment underground.



BPS or BIS (bits per second)  - The number of bits passing a point per second. A measure of the speed of transmission of digital information; used to describe the information transfer rate on a circuit.



Braid angle  - The smaller of the angles formed by the shielding strand and the axis of the cable being shielded.



Braid carrier  - A spool or bobbin on a braiding machine that holds one group of strands or filaments consisting of a specific number of ends. The carrier revolves during braiding operations.



Braid ends  - The number of strands used to make up one carrier. The strands are wound side by side on the carrier bobbin and lie parallel in the finished braid.



Braid  - Textile or metallic filaments interwoven to form a tubular structure which may be applied over one or more wires or flattened to form a strap (see shield).



Braiding machine  - Machine used to apply braids to wire and cable and to produce braided sleeving and braids for tying or lacing purposes. Braiding machines are identified by the number of carriers.



Branch joint  - A cable joint used for connecting one or more cables to a main cable.



Branch network  - Any network that is linked by a bridge to the backbone network or to another branch network in an extended LAN. Every network except the backbone network is a branch network.



Branch segment - Any segment that is linked by a repeater to the backbone segment in a single Ethernet LAN. Branch segments carry data grams to and from stations on the branch segment to the backbone segment.



Branch  - An intermediate cable distribution line in a broadband coaxial network that either deeds or is fed from a main trunk, same as a feeder.



Brazing  - The joining of ends of two wires, rods, or groups of wires with nonferrous filler metal at temperatures above 800°F (427°C).



Breakdown (puncture)  - A disruptive discharge through insulation.



Breakdown voltage  - The voltage at which the insulation between two conductors breaks down and becomes conductive.



Breaking strength  - The maximum load that a conductor attains when tested in tension to rupture.



Breakout  - The point at which a conductor or group of conductors breaks out from a multi-conductor cable to complete circuits at various points along the main cable.



BRI (basic rate interface)  - The ISDN term that refers to the basic ISDN interface of 2B +D. Operating at 144 kbps, BRI provides two B (bearer) channels at6 4 Kbps and a D (data) channel at 16 kbps.



Bridge  - A circuit that measures by balancing four impedances through which the same current flows: Wheatstone-Resistance, Kelvin-Low resistance, Schering-Capacitance, dissipation factor, dielectric constant, Wien-Capacitance, and dissipation factor.



Bridged Tap  - The multiple appearances of the same cable pair at several distribution points.



Bridging  - A term indicating that a high-impedance video line is paralleled, usually through a switch, to a source of video.



British standard wire gauge  - A modification of the Birmingham Wire Gauge and the legal standard of Great Britain for all wires; also known as Standard Wire Gauge (SWG), New British Standard (NBS), English Legal Standard and Imperial Wire Guide.



Broadband LAN  - A LAN that uses FDM (frequency division multiplexing) to divide a single physical channel into a number of smaller independent frequency channels. The different channels created by FDM can be used to transfer different forms of information; voice, data, and video.



Broadcast  - The act of sending a signal from one station on a LAN to all other stations, all of which are capable of receiving that signal.



BSC (binary synchronous communications)  - A byte- or character-oriented IBM communications protocol that has become an industry standard. It uses a defined set of control characters and sequences for synchronized transmission of binary-coded data between stations in a data communications system.



BSL (basic switching impulse insulation level)  - The crest value of a switching impulse voltage of a specified wave shape in which a high-voltage cable termination is required to withstand under specified conditions.



Buffer tube  - A loose, crush-resistant polymer tube applied over optical fibers to provide mechanical protection.



Buffer  - A protective coating in intimate contact with an optical fiber.



Building entrance area  - The area inside a building where cables enter and are connected to riser cables and where electrical protection is provided. The network interface, as well as the protectors and other distribution components for the campus subsystem, may be located here.



Building wire  - Commercial wires used in the building trades because they are independently tested and listed in the National Electric Code, such as types RHH, RHW, THW and THHN wire.



Buna  - A synthetic rubber insulation of styrene butadiene; was known as GR-S, now known as SBR (Styrene Butadiene Rubber).



Bunch strand  - A conductor arrangement in which all individual wires are twisted in the same direction without regard for geometrical arrangement.



Buncher  - A machine that twists wires together in a random arrangement.



Buoyant cable  - Originally military type MIL-C-2401 with built-in floatation ability. Many power and communications applications using numerous types and sizes have been developed using buoyancy.



Buried cable - A cable installed directly in the earth without use of underground conduit, also called "direct burial cable."



Bus and tag (serpentine) cable assembly (IBM)  - This assembly used as an interface from IBM 360/370/380 mainframe computers.



Bus network  - A one-cable LAN, in which all workstations are connected to a single cable. On a bus network, all workstations hear all transmission on the cable. Each workstation then selects those transmissions addressed to it.



Bus  - A network topology that functions like a signal line that is shared by a number of nodes.



Bus-bar wire - Un-insulated tinned copper wire used as a common lead.



Bushing  - A mechanical device used as a lining for an opening to prevent abrasion to wire and cable.



Butt splice  - A splice wherein two wire ends butt against each other, or against a stop, in the center of a splice.



Butt wrap  - Tape wrapped around an object or conductor in an edge-to-edge condition.



Butyl rubber  - Synthetic rubber formerly used for electrical insulating purposes.



BX  - A common type of armored building wire rated 600 volts.



Byte  - A collection of bits operated upon as a unit. Most bytes are eight bits long, and most character sets use one byte per character. The capacity of storage devices is frequently given in bytes or in K bytes (K meaning 1,024 bytes).

C

C - Symbol designation for capacitance, bias supply and centigrade.


C-conditioning - A type of line conditioning that controls attenuation, distortion and delay distortion to within specific limits.


C-Connector - A bayonet-locking connector for coax; the C refers to Carl Concelman.


C mount/CS mount - CCTV lenses are available in two different lens mounts. C mount lenses have a flange back distance of 17.5 mm vs. 12.5 mm for CS mount lenses. Many of today's cameras can accept either type of lens, but it is important to make sure the camera and lens are compatible and set up properly. C mount lenses can be used on CS mount cameras by utilizing a 5 mm adapter or adjusting the camera for C mount lenses. Because of the short back focal distance, CS mount lenses can only be used on CS mount cameras. Your picture will be out of focus if you use a CS mount lens on a C mount camera.


CCD (charged coupled device) - A CCD chip that is the pickup device on a camera, performing a similar function as a camera tube.


Cabinet - A physical enclosure for rack-mount equipment; standard cabinets have 1 3/4 in. zvertical spacing between mounting holes and 19 in. wide horizontal spacing between mounting rails.


Cable - A cable may be a small number of large conductors or a large number of small conductors cabled together, usually color coded and with a protective overall jacket.


Cable assembly - 1. A cable assembly is a cable with plugs or connectors on each end for a specific purpose. It may be formed in various configurations. 2. See PATCH CORD.


Cable belted - A multi-conductor cable having a layer of insulation over the assembled insulated conductors.


Cable-based LAN - A shared-medium LAN that uses a cable for its transmission medium.


Cable clamp - A device used to give mechanical support to the wire bundle or cable at the rear of a plug or receptacle.


Cable clamp adapter - A mechanical adapter that attaches to the rear of a plug or receptacle to allow the attachment of a cable clamp.


Cable concentrator - A device that converts several individual cables to a larger single cable without loss of signal information.


Cable core - The portion of an insulated cable lying under a protective covering.


Cable core binder - A wrapping of tapes or cords around the conductors of a multiple-conductor cable used to hold them together.


Cable filler - The material used in multiple-conductor cables to occupy the interstices formed by the assembly of the insulated conductors, thus forming a cable core.


Cable joint - A completely insulated splice, or group of insulated splices, contained within a single protective covering or housing. In some designs, the insulating material may also serve as the protective covering.


Cable loss - The amount of RF (radio frequency) signal attenuated by coaxial cable transmission. The cable attenuation is a function of frequency, media type and cable distance. For coaxial cable, higher frequencies have greater loss than lower frequencies and follow a logarithmic function. Cable losses are usually calculated for the highest frequency carried on the cable.


Cable Pressurized - A cable having a pressurized fluid (gas or oil) as part of the insulation; nitrogen and oil are the most common fluids.


Cable sheath - The protective covering applied to cables.


Cable spacer - An aerial distribution cable made of covered conductors held in place by insulated spacers; designed for wooded areas.


Cable support - A device to mount a cable on a supporting member.


Cable & cabling system - In LAN technology, the medium used to interconnect stations; often called the premises network.


Cable tilt - The increase in cable attenuation as the frequency increases.


Cable, tray - A multi-conductor cable having a nonmetallic jacket designed for use in cable trays per the National Electrical Code.


Cabling - The method by which a group of insulated conductors is mechanically assembled (or twisted together).


CAD - Computer aided design.


CAM - Computer-aided manufacture.


Campus subsystem - The part of a premises distribution system that includes the cable, in rebuilding distribution facilities, protectors and connectors that enable communications among multiple buildings on a premises.


Candlepower - The unit measure of an incident light.


Capacitance - The ability of a dielectric material between conductors to store electricity when a difference of potential exists between the conductors. The unit of measurement is the farad, which is the capacitance value that will store a charge of one coulomb when a 1-volt potential difference exists between the conductors. One farad is the capacitance value that will permit one ampere of current, when the voltage across the capacitor changes at the rate of one volt, per second.


Capacitance direct - The capacitance measured from one conductor to another conductor through a single insulating layer.


Capacitance mutual - The capacitance between two conductors (typically of a pair) with all other conductors, including shield, short circuited to ground.


Capacitance unbalanced - An inequality of capacitance between the wires of two or more pairs that result in a transfer of unwanted signal from one pair to others.


Capacitance unbalanced-to-ground - An inequality of capacitance between the ground capacitance of the conductors of a pair, which results in a pickup of external noise energy, usually from power transmission lines.


Capacitive coupling - Electrical interaction between two conductors caused by the potential difference between them.


Capacitive reactance - The opposition to alternating current due to the capacitance of a capacitor, cable or circuit. It is measured in ohms and is equal to 1/6.28 fC 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, types of dielectric and spacing between the conducting surfaces.


Capillary action - Movement of a liquid along a small interstice due to surface tension.


Carbon block - A device for protecting cable from being hit by lightning strikes in electrical storms. The carbon block consists of two electrodes spaced, so any voltage above the design level is arced from line to ground. Carbon block protectors are used commonly in both local customer offices and central offices. They are effective, but can be destroyed if high voltage is directly applied-as in a direct strike by lightning. See also GAS DISCHARGE TUBE.


Carrier - (1) An AC electrical signal that is used to carry information. (2) The woven element of a braid consisting of one or more ends (strands) which creates the interlaced effect. (3) A spindle, spool, tube, or bobbin (on a braiding machine) containing yarn or wire, employed as a braid.


Carrier band - A band of continuous frequencies that can be modulated with a signal.


Cascade - The number of amplifiers connected in series on a broadband trunk cable.


Cathode – (1) The negative electrode through that current leaves a nonmetallic conductor, such as an electrolytic cell. (2) The positive pole of a storage battery. (3) In vacuum tubes, the electrode that emits electrons.


Cathode-ray tube - The electronic tube that has a screen upon which a beam of electrons from the cathode can be made to create images; for example, the television picture tube.


Cathodic protection - Reduction or prevention of corrosion by making the metal to be protected the cathode in a direct current circuit.


CATV (community antenna television) - Refers to the use of a coaxial cable to transmit television or other signals to subscribers from a single head end location.


CATV cable - General term for all cables used for community antenna TV service and feeders, distribution and house drops.


CAU (controlled access unit) - IBM's 8230 is a wiring concentrator that supports up to 80 devices on a ring. The base unit, when used alone or in conjunction with up to four lobe attachment modules (LAMs), functions as a copper repeater or optical fiber converter at either four or sixteen megabits per second.


CB (Citizens band) - One type of two-way radio communication.


CBN (common bonding network) - A grounding term used in TIA standards.


CCIA - Computer and Communications Industry Association.


CCITT - A United Nations-sponsored organization, in Geneva, Switzerland, devoted to establishing worldwide communications standards. In English, it is known as the International Consultative Committee for Telephone and Telegraph.


CCS (copper clad steel) - Used in CATV, RG-59, 11 and 6 cables.


CCTV (closed-circuit television) - Video security cameras.


CCU (communications control unit) - In IBM 3270 systems, a communications computer, often a minicomputer, associated with a host mainframe computer. It may perform communications protocol, control message handling, code conversion, and error control and applications functions.


CCW - Continuously corrugated and welded. A type of cable armor.


CD (collision detection) - The ability of a transmitting node to detect simultaneous transmission attempts on a shared medium.


CD (carrier detect) - An RS-232 control signal (on pin that indicates the local modem is receiving a signal from the remote modem. Also called received line signal detector (RSLD) and data carrier detect (DCD).


CDMA (code division multiple access) - A wireless (cellular) telephony.


CDR - Call detail recording.


Cellular polyethylene - Expanded or "foam" polyethylene, consisting of individual closed cells of inert gas suspended in a polyethylene medium, resulting in a desirable reduction of dielectric constant.


Cenelec - Comite European de Normalization Electrique. European Electrical Standards Institute.


Certificate of compliance - A written statement normally generated by a quality control department that states that the product being shipped meets a particular specification.


Certified test report (CTR) - A report reflecting actual test data on the cable shipped. Tests are normally conducted by the quality control department and show that the product being shipped meets the required test specifications.


CFM (cubic feet per minute) - Usually associated with air flow and cooling systems.


CFR (Code of Federal Regulations) - The general and permanent rules published in the Federal Register by the executive departments and agencies of the federal government.


Channel – (1) A path for electrical transmission, also called a circuit facility, line, link or path. (2) A specific and discrete bandwidth allocation in the radio frequency spectrum (for example, in a broadband LAN) utilized to transmit one information signal at a time.


Channel translator - Device used in broadband LANs to increase carrier frequency, converting upstream (toward the head-end) signals into downstream signals (away from the head-end).


Characteristic impedance - A frequency dependent resistance that quantifies the complex opposition to current flow offered by a transmission line.


Charge - The cause of material bodies exerting forces on each other of repulsion or attraction. The unit of measure is the coulomb, which corresponds to a charge of 6.24 x 1,018 electrons.


Charging current - See CURRENT, CHARGING.


Chemical Stripping - Removal of insulation by chemical means.


Chlorosulfonated polyethylene (CSP) - A rubbery polymer used for insulations and jackets. Previously manufactured by E.I. DuPont under the trade name of Hypalon.


CI Cable - Circuit Integrity cable. An optional rating for UL Listed cable types that meet the two-hour fire survival requirements of UL Standard 2196, e.g., FPLP-CI.


CIC Cable - Circuit Integrity in Conduit cable. A generic term for cables that meet the two-hour fire survival requirements of UL Standard 2196 when installed in metallic conduit per UL category FHIT.


CIF (common intermediate format) - A video resolution format sometimes called compressed image format. The resolution ratings of all digital or IP cameras are given in multiples or divisions of CIF. In an image, it is true grid resolution based upon the number of pixels in horizontal rows and vertical columns.


Cigarette wrap - Tape insulation wrapped longitudinally instead of spirally over a conductor.


Circuit - A system of conducting media designed to pass an electric current.


Circuit switching - A switching technique in which an information path (i.e., circuit) between calling and called stations is established on demand for exclusive use by the connected parties until the connection is released.


Circuit tracing - Locating or identifying a specific conductive path.


Circular mil (CM) - A term universally used to define cross-sectional areas of conductors. It is an area equal to the area of a circle 1/1000 of an inch in diameter. As the number of circular mils increase, the size of a wire increases.

Cladding - The low refractive index material that surrounds the core of an optical fiber.


Clad wire - Different from coated wire, it is any metal covered with a relatively heavy coating of different metal, such as copper weld (copper over steel) or alum-o-weld (aluminum over steel). See COATED WIRE.


CLC - IBM's abbreviation for cluster controller. The central node in a star-shaped cluster network, which governs all message traffic to and from the other nodes.


Closed architecture - An architecture that is compatible only with hardware and software from a single manufacturer. Contrast with OPEN ARCHITECTURE.


Closed cell - Foamed or cellular material with intact cell walls, usually filled with air. Generally harder, better insulating, but more expensive than open cell material.


Closet, telecommunications - An enclosed space for housing telecommunications equipment, cable terminations and cross-connects. The closet is the recognized cross-connect between the backbone and horizontal cabling.


Cluster - A collection of terminals or other devices in a single location.


CMIP (common management information protocol) - The network management standard by OSI.


CMIS (common management information services) - An OSI network management standard. CMIS services are provided by CMIP.


CMOS (complimentary-symmetry metal oxide semiconductor) - An imaging device used in some low-end cameras.


CNR - Carrier to noise ratio.


CO - Central office.


CO lines - These are the lines connecting your office to your local telephone company's central office, which in turn connects you to the nationwide telephone system.


Coated wire - Any metal covered by a relatively thin coating of a different metal such as tin, zinc or other alloy by a dip bath and wipe process, often at high speeds in line with insulating equipment.


Coatings - Light is lost by reflection from optical surfaces that are intended to be refractors only. This loss is effectively reduced by very thin coatings on the lens surfaces. This can be seen as a blue or violet hue on the lens surface.


Coaxial cable - A cylindrical transmission line comprised of a conductor centered inside a metallic tube or shield, separated by a dielectric material and usually covered by an insulatingjacket.


Codec - An assembly comprising an encoder and a decoder in the same equipment.


Coherent source - A fiber optic light source that emits a very narrow, unidirectional beam of light of one wavelength (monochromatic).


Coil effect - The inductive effect exhibited by a spiral wrapped shield, especially above audio frequencies.


Cold bend - Generally refers to a test to determine cable or wire characteristics at low temperatures. The test specimen is cooled in a low-temperature box to a specified temperature. The wire specimen is then wound around a mandrel after which it is examined for cracks or other defects caused by bending at low temperatures.


Cold flow - Permanent deformation of the insulation due to mechanical pressure (not due to heat softening).


Cold-drawing - Reducing the cross section by pulling through a die or dies at a temperature lower than recrystallization.


Collision - Overlapping transmissions that occur when two or more nodes attempt to transmit at or about the same instant. Their interference is a collision.


Collision detection (CD) - The ability of a transmitting node to detect simultaneous transmission attempt: a shared medium.


Color burst - The portion of a composite video signal that comprises a few cycles of a sine wave of chrominance subcarrier frequency used to establish a reference for demodulating the chrominance signal.

Color code - A color system for wire or circuit identification by use of solid colors, tracers, braids, surface printing, etc.


Combination stranded conductor - A conventional concentric conductor in which the wires in the outer layer are larger in diameter than the wires in the inner layer or layers and the diameters of all wires are within plus and minus 5 percent of the nominal wire diameter for the same size non-combination stranded conductor.


Common axis cabling - In multi-conductor constructions, a twisting of all conductors about a "common axis" to result in smaller diameter constructions; Tends to result in greater susceptibility to electromagnetic and electrostatic interference.


Common carrier - A data communications utility company or a government organization that furnishes communications services to the general public and is usually regulated by local, state or federal agencies. Often PTTs provide these services outside, and the USA Telco's inside.


Common mode noise - Noise caused by a difference in ground potential. By grounding at either end rather than both ends (usually grounded at source) one can reduce this interference.


Communications controller - A device within a host computer that allows communication with the LAN.


Communications protocol - The means used to control the orderly exchange of information between stations on a data link or on a communications network or system, also called line discipline or protocol, for short.


Communications server - An intelligent service providing communications functions. Usually, an intelligent, specially configured node on a LAN designed to enable remote communications access to, and egress from, LAN users.


Compact stranded conductor - A unidirectional or conventional concentric conductor manufactured to a specified diameter, approximately 8 to 10 percent below the nominal diameter of a non-compact conductor of the same cross-sectional area.


Composite - The line side of a concentrator or multiplexer that includes all the multiplexed data.


Composite cable - A cable containing more than one gauge size or a variety of circuit types, e.g., pairs, triples, quads, coaxial, etc.


Composite clad wire - A wire having a core of one metal with a fused outer shell of a different metal.


Composite conductor - A conductor consisting of two or more types of wire, each type of wire being plain, clad, or coated-stranded together to operate mechanically and electrically as a single conductor.


Composite video - The combined video signal that includes the picture signal, the vertical and horizontal blanking and synchronizing pulses.


Compound filled splice - Joints in which the joint housing is filled with an insulating compound that is non-fluid at normal operating temperatures.


Compressed stranded conductor - A conventional concentric conductor manufactured to a diameter not more than 3 percent below the nominal diameter of a non-compressed conductor of the same cross-sectional area.


Compression - Two types are available: data compression, which reduces the number of bits required to represent data (accomplished in many ways, including using special coding to represent strings of repeat characters or using fewer bits to represent the more frequently used characters); analog compression that reduces the bandwidth needed to transmit analog signal, also called compaction.


Compression lug or splice - A connection installed by compressing the connector onto the strand, ideally creating a cold weld.


Compromised balanced network - Circuitry in a D4 channel unit card that provides a matching interface to the customer loop to facilitate proper transmission characteristics.


Computer room - Any room or area where several multiuser computers are located.


Concentration - Collection of data at an intermediate point from several low- and medium-speed lines for transmission across one high-speed line.


Concentrator - One of the basic components of an ISN system. The concentrator accepts as many as 40 data streams from terminals and hosts, and multiplexes them for transmission through an optical fiber cable connected to the packet controller. In turn, it accepts a multiplexed data stream from the Packet Controller, divides it into multiple signals (de-multiplexes) and forwards messages to the proper devices.


Concentric lay conductor - A layer of un-insulated wires twisted around a central wire with subsequent layers spirally wrapped around the inner layers to form a single conductor.


Concentric stranding - A group of un-insulated wires twisted together and containing a center core with subsequent layers spirally wrapped around the core to form a single conductor.


Concentricity - The measurement of the location of the center of the conductor with respectto the geometric center of the circular insulation.


Conditioning - The "tuning" or addition of equipment to improve the transmission characteristics or quality of a leased voice-grade line, so it meets specifications for data transmission.


Conductance - The ability of a conductor to carry an electric charge. The real part of admittances. It is the reciprocal of resistance and is measured in mhos.


Conductivity - The ability of a material to allow electrons to flow, measured by the current per unit of voltage applied. Usually expressed as a percentage of copper conductivity (copper being 100 percent). Also, it is the reciprocal of resistivity. I t has units of mhos/meter.


Conductor - A material suitable for carrying an electric current.

    Compact round conductor - A conductor constructed with a central wire surrounded by one or more pre shaped (non-round) helically-laid wires and formed into final shape by rolling, drawing or other means.

    Concentric-lay conecctor - A conductor constructed with a central wire surrounded by one or more layers of helically-laid wires.

    Conventional concentric conductor - A conductor constructed with a central wire surrounded by one or more layers of helically-laid wires. The direction of lay is reversed in successive layers and generally with an increase in length of lay for successive layers.

    Equilay conductor - A conductor constructed with a central wire surrounded by more than one layer of helically-laid wires, all layers having a common length of lay, direction of lay being reversed in successive layers.

    Parallel core conductor - A conductor constructed with a central core of parallel-laid wires surrounded by one layer of helically-laid wires.

    Rope-lay conductor - A conductor constructed of a bunch-stranded or a concentric-stranded member or members, as a central wire, around which are laid one or more helical layers of such members.

    Unidirectional conductor - A conductor constructed with a central wire surrounded by more than one layer of helically-laid wires, all layers having a common direction of lay, with increase in length of lay for each successive layer.

    Unilay conductor - A conductor constructed with a central wire surrounded by more than one layer of helically-laid wires, all layers having a common length and direction of lay.


Conductor core - The center strand or member about which one or more layers of wires or members are laid helically to form a concentric-lay or rope-lay conductor.


Conductor shield - A conducting layer applied to make the conductor a smooth surface in intimate contact with the insulation; sometimes called Extruded Strand Shield (ESS).


Conduit - A pipe, usually metal, that runs either from floor to floor, or along a floor or ceiling, to protect cables. In the riser subsystem, when riser closets are not aligned, conduit is used to protect cable and provide the means for pulling cable from floor to floor. In a horizontal subsystem, conduit may be used between a riser closet and an information outlet in an office or other room. Conduit is also used for in-conduit campus distribution, where it is run underground between buildings and intermediate manholes and encased in concrete.

Connecting block - A flame-retardant plastic block containing metal wiring terminals (insulation displacement contacts) that establish an electrically tight connection between the cable and the cross-connect wire.


Connecting hardware - A device providing mechanical cable terminations. Connection – (1) An established data communications path. (2) The process of establishing that path. (3) A point of attachment for that path.


Connection delta - Interconnection of three electrical equipment windings in a DELTA (triangular) configuration.


Connection diagram - Indicates the location and describes the types of connectors to be used at every junction in the distribution system.


Connection wye - Interconnection of three electrical equipment windings in WYE (star) configuration.


Connector - A metallic device of suitable electric conductance and mechanical strength, used to splice the ends of two or more cable conductors, or as a terminal connector on a single conductor. Conductors are sometimes spliced without connectors by soldering, brazing or welding. Connectors usually fall into one of the following types:

    Solder
    Welded
    Mechanical
    Compression or indent


Contact - The part of a connector that carries the electrical current.


Contact size - The largest size wire that can be used with the specific contact. Also, the diameter of the engagement end of the pin.


Contention - A "dispute" between two or more devices over the use of a common channel at the same time.


Continuity check - A test performed on a length of finished wire or cable to determine if an electrical current flows.


Continuous vulcanization - Simultaneous extrusion and vulcanization (cross linking) of wire insulating and jacketing materials; also referred to as CV cured.


Contrahelical - Wire strands spiraling in an opposite direction than the preceding layer within a wire or cable.


Control cable - A cable used for remote control operation of any type of electrical power equipment.


Controlled impedance cable - A package of two or more insulated conductors where impedance measurements between respective conductors are kept essentially constant throughout the entire length.


Copper-clad steel - Steel with a coating of copper welded to it before drawing as opposed to copper-plated. Synonymous with Copperweld.


Copperweld- Trademark of Copperweld Steel Co. for copper-clad steel conductor.


Copolymer - A polymer consisting of a "mixture" of two or more polymers.


Cord - A very flexible insulated cable.


Cord set - Portable cords fitted with a connector at one or both ends.


Core - (1) In cables, a component or assembly of components over which other materials are applied, such as additional components, shield, sheath or armor. (2) The light transmitting portion of an optical fiber that has a higher index of refraction than the cladding. The core is typically 50 or 62.5 microns in diameter for multimode and 8 to 9 microns for single-mode.


Corona - A discharge due to ionization of the air around a conductor due to a potential gradient exceeding a certain critical value. See PARTIAL DISCHARGE.


Corona resistance - The time that the insulation will withstand a specified level of ionizationthat does not result in the complete breakdown of the insulation.


Corrosion - The destruction of the surface of a metal by chemical reaction.


COS (Committee for Open Systems) - A group of major computer manufacturers whose intent it was to form standards of interconnection for computer systems. One result of their efforts was the 150/051 network model.


Coulomb - The derived 51 unit for quantity of electricity or electrical charge: One coulomb equals one ampere-second.


Counter EMF - The voltage opposing the applied voltage and the current in ac oil; caused by a flow of current in the coil; also known as back EMF.


Counterpoise wire - Bare copper wire used to offset the impact of lightning surges along high-voltage overhead lines and around the base of towers. Buried counterpoise wire is connected to overhead ground wires and towers. Numerous methods of application are used, dependent upon resistance of the soil at the tower base.


Coupling - The transfer of energy between two or more cables or components of a circuit.


Coupling loss - Signal losses in an optical fiber due to small differences in numerical aperture, core diameter, core concentricity and tolerances in connectors when two fibers are spliced together. Also known as splicing loss and transfer loss.

Coverage - The calculated percentage that defines the completeness with which a metal braid covers the underlying surface. The higher percentage of coverage, the greater the protection against external interference.


CPC - Customer premises communication. CPC (calling party control) - A signal from most electronic COs to indicate that the calling party has hung up. Sometimes called open loopsdisconnect. The timing on this signal ranges from 250 to 500 m/s.


CPE - Dow Chemical trademark for chlorinated polyethylene. A jacketing compound.


CPE (customer premises equipment) - A telecommunications term for voice or data equipment that resides at a customer's premises.


CPP (cable patch panel) - A panel, half of which is used to terminate cables coming from faceplates, and half of which is used to terminate cables coming from network or host connections. The connections are joined using patch cables.


CPS (cycles per second) - This is an obsolete designation and is now called hertz (Hz). The SI unit is the hertz: one cycle per second. CPS (characters per second) - When referring to printers, a measure of the average number of characters that the printer can print in one second.


CPU (central processing unit) - Actually the heart of a computer, but often used as a synonym for computer.


CRAC - Computer room air conditioner (data center term).


CRM - Customer relationship management.


Cross-bar switches - In older PABX technology, a switch having multiple vertical paths, multiple horizontal paths and electromagnetically operated mechanical means for connecting any vertical path with any horizontal path. Modern PABXs often use an electronic version of the cross-bar switch.


Cross-connect - The apparatus in a distribution system providing for the termination of twisted pairs or optical fibers and the rearrangement and testing of circuits. In a wire cross-connect, incoming and outgoing twisted pairs terminate on separate connecting blocks, and patch cords complete the circuits. In a light wave cross-connect, incoming and outgoing fibers terminate in connectors that fit into fiber couplings and single fiber jumpers complete the circuits.


Cross-connect field - A color-coded strip identifying the type of service carried on the cables terminated on a wire cross-connect terminal block. The color code is: - Green: central office trunks - Blue: station cables - Purple: ISN equipment, multiplexing devices, PBX ports - White: house cables - Yellow: auxiliary equipment (such as an application processor) - Orange: multiplexer ports (premises light wave system only) - Gray: tie cables (between riser and apparatus and satellite closets)


Cross-connect, horizontal - See HORIZONTAL CROSS-CONNECT.


Cross-linked - Intermolecular bonds created between long-chain thermoplastic polymers bychemical or electron bombardment means. The properties of the resulting thermosetting material are usually improved.


Cross-linked polyethylene - A dielectric material used for insulating and jacketing, also referred to as "XLP" or "XLPE."


Crosstalk - A type of interference caused by audio frequencies from one line being coupled into adjacent lines. The term is loosely used also to include coupling at higher frequencies.


CRT (cathode-ray tube) - A television-like picture tube used in terminals; CRT is commonly used as a synonym for the CRT terminal.


CRT wire - High-voltage lead wire for energizing cathode ray tubes.


CSA (Canadian Standards Association) - The Canadian Standards Association is a not-for-profit membership-based association serving business, industry, government and consumers in Canada and the global marketplace. Similar to UL in the United States.


CSA Certified - A product that has been tested and found to comply with applicable Canadian standards.


CSMA (carrier sense multiple access) - A contention technique that allows multiple stations to gain access to a single channel. A contended access method in which stations listen before transmission, send a packet and then free the line for other stations. With CSMA, although stations do not transmit until the medium is clear, collisions still occur; two alternative versions (CSMA/CA and CSMA/ CD) attempt to reduce both the number of collisions and the severity of their impact.


CSMA/CD/CA (carrier sense multiple access with collision detection) - A contention technique that allows multiple stations to successfully share a broadcast channel by avoiding contention via carrier sense and deference and managing collisions via collision detection and packet retransmission. See CSMA and COLLISION DETECTION.


CSO (composite second order) - A type of signal distortion in CATV transmission.


CSPE - A jacketing compound based on DuPont's Chlorosulfonated polyethylene (Hypalon). Sometimes abbreviated CSP.


CSU (channel service unit) - A digital DCE unit for DDS lines; interfaces with DSU on customer's premises.


CT (cable tray) - NEC Article 318. A cable marking indicating a single conductor cable

suitable for use in a cable tray.


CTB (composite triple beat) - A type of signal distortion in CATV transmission.


CTI - Computer telephony integration. Usually provides a screen-pop and other interaction.


Cure - To change the properties of a polymeric system into a more stable, usable condition by the use of heat, radiation or reaction with chemical additives.


Curing cycle - The time, temperature and pressure required for curing.


Curl- The degree to which a wire tends to form a circle after removal from a spool.


Current - The rate of transfer of electricity. The unit of current is the ampere, a rate of one coulomb a second.


Current alternating (AC) - An electric current that periodically reverses direction of electron flow. The number of cycles in a given unit of time (generally a second) is called the frequency of the current.


Current carrying capacity - The maximum current an insulated conductor can safely carry without exceeding its insulation and jacket temperature limitations. Same as ampacity.


Current charging - The current needed to bring the cable up to voltage; determined by the capacitance of the cable. The charging current will be 90° out of phase with the voltage.


Current density - The current per cross sectional area in units of amperes/meters2.


Current direct (DC) - Electrical current whose electrons flow in one direction only. It may be constant or pulsating as long as their movement is in the same direction.


Customer premises - Building(s) with grounds and appurtenances (belongings).


Cut-through resistance - The ability of a material to withstand mechanical pressure without damage.


CV - Continuous vulcanization. Insulation and jacketing curing process.


CWDM - Course wavelength division multiplexing.


CXR - Carrier. A continuous light wave or radio frequency that is transmitted over a cable and is modulated with a signal. The receiving terminal interprets any change in signal as information. Changes to the signal made by outside influences (noise) can cause the receiving terminal to misinterpret the information transmitted.


Cycle - The complete sequence, including reversal of the flow, of an alternating electric current.

D

D/A - Digital to analog.


DAC (digital to analog converter) - A device that converts a digital input to an analog output signal carrying equivalent information.


DACS - Digital access and cross-connect system.


Daisy chaining - The connection of multiple devices in a serial fashion. An advantage of daisy chaining is a savings in transmission facilities. A disadvantage is that if a device malfunctions all of the devices Daisy chained behind it are disabled.


DASD - Direct attached storage device.


DATA - Digitally represented information including voice, text, images and video.


Database - A large, ordered collection of information.


Data center - A building or a portion of a building whose primary function is to house a computer room and its support areas.


Data compression - Packing data into a reduced format. Compressed data are in "short-hand" form and must be decompressed before it can be used by the receiving computer.


Datagram - A packet that includes a complete destination address specification (provided by the user, not the network) along with whatever data it carries.


Data integrity - A measure of data communications performance, indicating a scarcity (or, ideally, the absence of) undetected errors.


Data rate - A measure of the signaling rate of a data link.


dB - Decibel. The standard unit used to express the relative strength of two signals. When referring to a single signal measured at two places in a transmission system, it expresses either a gain or loss in power between the input and output devices. The reference level must always be indicated, such as one mill watt for power ratio.


DBC - A measure of spurious signal level. The level is measured relative to the nominal un-modulated carrier level.


DBM - Absolute measure of signal power where 0 DBM is equal to one mill watt. Contrast with dB.


dBmV (decibel mill volt) - The level at any point in a system expressed in dBs above or below a one mill volt/75 ohm standard is said to be the level in decibel- mill volts or dBmV. Zero dBmV is equal to one mill volt across 75 ohms.


DB-9 (RS-449) - A 9-conductor EIA cable assembly used for interfacing VF lines to printers, PCs and all data compatible operations.


DB-15 (RS-422/RS-423) - A 15-conductor EIA cable assembly used as drop cable for Ethernet local area networks and for interfacing all freestanding a sync peripheral equipment, such as PCs, controllers, etc.


DB-25 (RS-232) - A 25-conductor round or flat EIA cable assembly used to interface most
IBM DEC, local area networks and all a sync compatible systems, such as connects mainframes, controllers, PCs, modems, etc.


DB-37 (RS-449) - A 37-conductor EIA cable assembly that connects data terminal equipment (DTE) and data circuit terminating equipment (DCE) employing binary serial data interchange.


DB-50 (RS-422/RS-423) - A 50-conductor EIA cable assembly meets interface needs of all high-volume circuit systems. Same standards as RS-232 connect controllers, PCs, modems, etc.


DC - Direct current. (See CURRENT, DIRECT.)


DC resistance - See RESISTANCE.


DC type lens - An auto iris lens with internal circuit that receives voltage and a video signal from the camera to adjust the iris.


DCE (data communications equipment) - In common usage, synonymous with modem; the equipment that provides the functions required to establish, maintain, and terminate a connection as well as the signal conversion required for communications between the DTE and the telephone line or data circuit.


DCL - Data carrier level.


DCS - Distributed control system. A type of industrial automation system in which the processors are distributed in various locations though out the facility.


DDA (direct digital access) - A 56 kbps digital data access through a 4 ESS switch.


DDNS (dynamic DNS) - A service that allows you to automatically (dynamically) upload your current IP info that has been assigned via DHCP.


DDS (digital data system) - A network that transmits data signals point-to-point.


DecaBDE - Decabromodiphenyl ether. A type of brominated flame retardant sometimes used in wire and cable and other products. A type of polybrominated biphenyl ether (PBDE).


Decibel (dB) - One-tenth of a bell. It is equal to 10 times the logarithm of the power ratio, 20 times the log of the voltage ratio or 20 times the log of the current ratio. One decibel is the amount by which the pressure of a pure sine wave of sound must be varied in order for the change to be detected by the average human ear. The decibel can express an actual level only when comparing with some definite reference level that is assumed to be zero dB.


Delay skew - The difference in propagation delay between the fastest and slowest pair within the same cable sheath. Usually expressed in nanoseconds.


Demand – (1) The measure of the maximum load of a utility's customer over a short period of time. (2) The load integrated over a specified time interval.


Demarcation point - A point where the operational control or ownership changes.


Demarcation strip - The terminal strip or block (typically a 66-block) that is the physical interface between the phone company's lines and the lines going directly to your own phone system.


Demodulation - The process of separating a data (digital) signal from an analog carrier signal. Opposite of MODULATION.


Demultiplexing - The process of breaking a composite signal into its component channels; the reverse of multiplexing.


DEMUX - Demultiplexer.


Depth of field - The front to back zone in a field of view that is in focus in the televised scene.
With a greater depth of field, more of the scene, near too far, is in focus. Increasing the f-stop number increases the depth of field of the lens. Therefore, the lens aperture should be set at the highest f-stop number usable with the available lighting. The better the lighting the greater the depth of field possible. In other words, the depth of field is the area in front of the camera that remains in focus. The larger the f-number the greater is the depth of field.


Derating factor - A factor used to reduce the current carrying capacity of a wire when used in environments other than that for which the value was established.


DES (data encryption standard) - An encryption method originally developed by IBM in the 1970s.


Destination - Receiver of data; data sink.


Detector - A fiber optic device that picks up light from the fiber and converts the information into an electrical signal.


Device, as related to a workstation - An item such as a telephone, personal computer, or graphic or video terminal.


Device, as related to protection - A protector, a protector mount, a protector unit or a protector module.


Dew point-The temperature at which vapor starts to condense (liquefy) from a gas-vapor mixture at constant pressure.


DHCP (Dynamic Host Configuration Protocol) - A protocol that automatically assigns an IP address to a device requesting an IP address. A DHCP server automatically issues network devices with IP addresses when they connect to the network.


Diagnostics - Programs or procedures used to test a piece of equipment, a communications link or network, or any similar system.


Dial-up line - Your average everyday home or business phone line. See also LEASED LINE.


Dielectric - An insulating (non-conducting) medium.


Dielectric breakdown - Any change in the properties of a dielectric that causes it to become conductive. Normally the failure of insulation is because of excessive voltage.


Dielectric constant - The property of an insulation that determines the electrostatic energy stored per unit volume for unit potential gradient. It is expressed as a ratio. K for air is 1.0, while that for polyethylene is 2.2. Therefore, the capacitance of polyethylene is 2.2 times that of air. It is also referred to as specific inductive capacity or permittivity.


Dielectric dispersion - The change in relative capacitance due to a change in frequency.


Dielectric heating - The heating of insulating material when placed in a radio-frequency field, which is caused by internal losses 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 an alternating electric field is applied.


Dielectric strength - The maximum voltage that insulation can withstand without breaking down; usually expressed as a gradient in V/mil (volts per mil). Polyethylene for example has a dielectric strength of about 800 V/mil.


Dielectric strength testing - A common test performed on electrical products that is often called hi-pot testing. A voltage higher than normal operating voltage is applied across the insulation. This test can increase product reliability by detecting faulty workmanship.


Differential amplifier - One that has two input signal connections in addition to the zero signal reference lead. The output is the algebraic sum of the instantaneous voltages appearing between the two input signal connections.


Digital - Discretely variable as opposed to continuously variable. Data characters are coded in discrete, separate pulses or signal levels. Contrast with ANALOG.


Digital line - The facility that carries the digital bit stream from one location to another.


Digital loopback - A diagnostic test that forms the loop at the modem's DTE interface.
See LOOPBACK.


Digital PBX - A PBX that switches voice and data traffic as digital signals.


Digital signal - An electrical signal consisting of two discrete voltage levels, encoding information as a series of ones and zeros.


Digroup - A group of 24 customer channels.


DIN (Deutsches Institut fur Normung) - The German standard for many products.


DIN connected cable assembly 5 and 8 conductors - Used for interfacing the IBM keyboards and other compatible systems.


DIP (dual in-line pins) - Term used to describe the pin arrangement on an integrated circuit (IC) or a multiple (electric) switch.


DIP coating - An insulating coating applied to the conductor by passing the conductor through an applicator containing liquid insulating medium.


Diplex filter - A passive filter that combines and separates the inbound and outbound pass bands in a broadband system.


Direct burial cable - A cable installed directly in the earth.


Direct capacitance - The capacitance measured directly from conductor to conductor through a single insulating layer.


Direct connection - A connection between a terminal and a host computer that does not use terminal servers and Ethernet. Direct connections use the RS-232 or DEC423 interface.


Direction of lay - The lateral direction, designated as left-hand or right-hand, in which the wires of a conductor run over the top of the conductor as they recede from an observer looking along the axis of the conductor.


Directional coupler - A passive device used in a cable system to divide or combine unidirectional RF power sources.


Discrete access - In LAN technology, an access method used in star LANs; each station has a separate (discrete) connection through which it makes use of the LAN's switching capability. Contrast with SHARED ACCESS.


Dispersion - The variation of the refractive index of an optical fiber with wavelength, causing light of different wavelengths to travel at different velocities in the fiber.


Display station, display terminal - A device consisting of a keyboard and video or CRT display.
In the IBM 3270 Information Display System, a 3278 is an example of a display station; in an
ASCII CRT terminal, it is an example of a display terminal.


Dissipation factor - Energy lost when voltage is applied across insulation. The cotangent of the phase angle between voltage and current in a reactive component. Dissipation factor is quite sensitive to contamination and deterioration of insulation. Also known as power factor (of dielectrics).


Distortion factor - An undesired change in waveform as the signal passes through a device.


Distortion level - (1) The ratio, measured in dB, of unwanted distortion to desired carrier. (2) Any unwanted electromagnetic component present on the desired RF modulated carrier. (3) The unwanted changes in signal or signal shape that occur during transmission between two points.


Distributed architecture - In LAN technology, a LAN that uses a shared communications medium; used on bus or ring LANs; uses shared access methods.


Distributed computing - The name of the trend to move computing resources such as minicomputers, microcomputers or personal computers closer to individual workstations. See also DISTRIBUTED PROCESSING.


Distributed processing - An arrangement that allows separate computers to share work in the same application program. Often erroneously used to mean distributed computing.


Distribution amplifier - A device that accepts a (video) signal and sends it out to a number of independent outputs.


Distribution cable - In a CATV system, the transmission cable from the distribution amplifier to the drop cable. In an electric power system, provides low-voltage service to the customer.


Distribution frame - A structure with terminations for connecting the permanent wiring of a facility in such a manner that interconnection by cross-connections may be readily made.


Distribution panel - A wiring board that provides a patch panel function and mounts in a rack.


Disturbed conductor - A conductor that receives energy generated by the field of another conductor or an external source such as a transformer.


Disturbing conductor - A conductor carrying energy whose field(s) creates spurious energy in another conductor.


DIW (D-Inside Wire) - Also called unshielded twisted pair (UTP). The standard wire originally designated for voice communications. Typically, DIW consists of four pairs of copper wire in the same sheath. Each pair is twisted around one another.


DLC - Digital loop carrier.


DNIS - Dialed number identification service.


DNS (Domain Name System [or Server/Service]) - A service that assigns and translates registered friendly names (registered domain names) into IP addresses. In large networks a domain name server is literally a "name" server. It associates and remembers given names to corresponding IP addresses. (i.e., a more easily remembered name such as "MDF camera" rather than by using a long IP address number like 192.36.253.80).


DOCSIS (Data Over Cable Service Interface Specification) - A standard for cable modem products drafted in 1996. It was developed to ensure that cable modem equipment built by a variety of manufacturers is compatible, as dial-up modems are.


DOD (Department of Defense) - Part of the U.S. government executive branch that handles military matters, including data communications; responsible for some LAN associated protocols and standards such as TCP/IP.


Dose, integrated (nuclear power) - Cumulative radiation dosage over a given period of time.


Download - The process of loading software into the nodes of a network from one node or device over the network media.


Downstream - (1) On a ring network, the direction of data flow. (2) The direction on the cable from the head end to the modems.


Drain wire - An un-insulated wire in contact with a shield throughout its length, used for terminating the shield.


Drawing, wiring diagram - In wire manufacturing, pulling the metal through a die or series of dies to reduce diameter to a specified size. Shows how the devices are interconnected.


Drop- (1) The physical location of the end of an Ethernet transceiver cable. (2) A cable that leads from a faceplate to the distribution panel in a wiring closet. When the IBM Cable System is used with the IBM token-ring network, a drop may form part of a lobe. See LOBE. (3) Individual connections (sometimes called nodes) on a multipoint (also called multi-drop) circuit. (4) The coaxial cables which connect the taps to the devices on the plant floor.


Drop cable – (1) In a CATV system, the transmission cable from the distribution cable to a dwelling. (2) The smaller diameter flexible coaxial cable used for drops (RG-59, RG-6, RG-11).


DSF - Dispersion shifted fiber.


DSLAM (digital subscriber line access multiplexer) - On a DSL service it separates voice and data traffic at the central office.


DSR - Data Set Ready. One of the control signals on a standard RS-232-C connector. It indicates whether the data communications equipment is connected and ready to start handshaking control signals so that transmission can start.


DSS/BLF - Direct station selector/busy lamp field.


DSU (data service unit) - Device designed to transmit digital data on transmission facilities. Typically a device that interfaces DTE (data terminal equipment) to a line contacting a data port channel to allow digital communications without a modem. It is used with a CSU when the DTE lacks complete digital line interface capability or alone (i.e., without a CSU) when the DTE includes digital line interface capability.


DS-0 (Digital Service, level 0) - It is 64,000 bps, the worldwide standard speed for digitizing one voice conversation.


DS-1 (Digital Service, level 1) - It is 1.544 Mbps in North America and 2.048 Mbps elsewhere.
1.544 Mbps is the old Bell System standard and 2.048 is the CCTIT standard.


DS-1C (Digital Service, level 1C) - It is 3.152 Mbps in North America.


DS-2 (Digital Service, level 2) - It is 6.312 Mbps in North America.


DS-3 (Digital Service, level 3) - Term referring to the signaling rate of a T3 network: 44.736 Mbps.


DTE (data terminal equipment) - User equipment. The end-user machine (terminal, computer, controller, etc.) that plugs into a unit which is the termination point of the communications circuit (DCE).


DTR - Data terminal ready. An RS-232 modem interface control signal (sent from the DTE to the modem on pin 20) that indicates that the DTE is ready for data transmission and which requests that the modem be connected to the telephone circuit.


Dual cable - A two-cable system in broadband LANs in which the coaxial cable provides two physical paths for transmission, one for transmit and one for receive, instead of dividing the capacity of a single cable.


Duct - A pipe, tube or conduit through which cables or wires can be passed. Duct space is always at a premium. If you ever install a duct, make sure it is twice the diameter you ever think you need. If you're lucky, it will last a couple of years. The cost of putting in thicker or extra ducts is peanuts compared to the cost of having to install additional ones later.


Dumb terminal - The dumb terminal is an asynchronous terminal that may operate at speeds as high as 9,600 bps or higher. The dumb terminal is an ASCII terminal that, although it may be "intelligent" in many of the functions it provides, it uses no communications protocol.


Duofoil - Belden trademark for a shield in which metallic foil is applied to both sides of a supporting plastic film.


Duplex - Two-way data transmission on a four-wire transmission cable.


Duplex (multiplexer) - A multiplexer that allows the user to look at multi screen images while performing time multiplex recording.


Duplex cable - A cable composed of two insulated single conductor cables twisted together


DUT - Device under test.


DVI (digital visual interface or digital video interface) - Video standard and connector for digital and analog monitor connections. DVI-A: analog monitor only; DVI-D: digital video only. Works up to 16.5 feet (5 m).


DWDM - Dense wavelength division multiplexing.


Dwell time - The length of time a switcher holds on a camera before moving on to the next in sequence.


DVR (digital video recorder) - A device that records video in a digital format on an internal (or external) hard disk drive. This is in contrast to a traditional VCR (videocassette recorder) that records video in an analog format on tape media. Some DVRs are combined with a multiplexer in the same unit, which allows multiple cameras to be simultaneously recorded, played back or viewed. Some common features of DVRs are fast picture retrieval, date and time search, maintenance free, no tapes to change or heads to clean, time lapse and event alarm recording, adjustable recording rates per video input, programmable timer, audio recording, alarm event logs and water-marking of images to prevent tampering. (Not all DVRs have the same features.)


DX (duplex signaling) - Signaling system that occupies that same cable pair as the voice path, yet does not require filters.

E

E - (1) Symbol for voltage. Usually used to represent direct voltage or the effective (root-mean-square) value of an alternating voltage. (2) A UL cable type. Elevator lighting and control cable.


EAC – Electronic Access Control.


EAP - Extensible Authentication Protocol.


Earth - British terminology for zero-reference ground.


Earthing conductor - A conductor that goes from a known earth ground to a device to be grounded.


Eccentricity - Like concentricity, a measure of the center of a conductor's location with respect to the circular cross section of the insulation. Expressed as a percentage of displacement of one circle within the other.


Echo – (1) A faint return of the transmitted signal to the originating modem when a signal is related by a communications satellite. (2.) The interference caused when a modem receives its own signal, experienced when two 9,600-bps modems communicate, each using most of the available bandwidth.


Echo canceller - A device that digitally compensates for echo signals that appear on telecommunications circuits.


Echo suppressor - A device used by telcos or PTTs that blocks the receive side of the line during the time that the transmit side is in use.


Echoplex - A method of checking data integrity by returning characters to the sending station for verification of data integrity.


Ecma International (European association for standardizing information and communications systems) - Before 1994, Ecma was known as the European Computer Manufacturers Association (ECMA). After 1994, Ecma was implemented as a trademark to represent the historical aspect of the organization. Ecma is an industry association dedicated to the standardization of information and communications technology and consumer electronics.


ECTFE - (Halar) An Ausimont Co. trademark for ethylene chlorotrifluoro ethylene. Used as an insulation or jacketing material.


ED (ending delimiter) - In the FDDI frame and token-format blocks, this contains non-data symbols to indicate the end of the frame. The delimiter is eight bits long for a token (two consecutive T symbols) and four bits long (a single T symbol) for all other frames.


Eddy current - An electric current induced in a conductor by a varying magnetic field.


EDFA - Erbium doped fiber amplifier (fiber amplifier).


EFM (Ethernet in the First Mile) - There is a standard IEEE 802.3ah.


EEPROM (electrically erasable programmable read only memory) - An EPROM that can be cleared with electrical signals rather than the traditional ultraviolet light.


EFS (end of frame sequence) - In the FDDI frame and token-format blocks, this consists of ED (encoding delimiter) and FS 9 (frame status) fields, which ensure a clear function occurs close to each frame.


EI - The European standard for high-speed data transmission at 2.048 Mbps. Thirty-two 64 kbps channels are provided.


EI (electronic iris) - Automatically changes a CCD camera's shutter to mimic auto iris control, allowing fixed or manual iris lenses to be used in a range of areas that used to require an auto iris lens.


EIA crossover cable - A seven-wire cable used to change a DCE to DTE. It is terminated on both ends with a male connector and serves both the AIM8 and AIM4 circuits.


EIA RS-232-C - A standard, defined by the Electronics Industries Association, describing the electrical, mechanical and functional characteristics of the connections between devices exchanging data in serial binary form.


EIA RS-232-C port - A 25-pin male or female connector compatible with RS-232-C signals and cable.


EIA signal - A digital signal having a number of characteristics (in time duration, voltage and current) defined by the Electronics Industries Association as standards for data communication.


Elastomer - Any material that will return to its original dimensions after being stretched or distorted.


Electro-osmosis - The movement of fluids through dielectrics because of electric current.


Electro-tinned - Electrolytic process of tinning wire using pure tin.


Electromagnet - A device consisting of a ferromagnetic core and a coil that produces appreciable magnetic effects only when an electric current exists in the coil.


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. inductive coupling.


Electromechanical cables - Dual purpose composite cables made up of support strands capable of supporting predetermined loads together with communication, coaxial or power as integral members of a finished cable.


Electromotive Force (EMF) - Pressure or voltage. The force that causes current to flow in a circuit.


Electron - An elementary particle containing the smallest negative electric charge; Mass=9.1 x 1,031; Charge=0.16 attocoulom; Diameter=1 femtometer.


Electron volt - A measure of the energy gained by an electron passing through an n electric field produced by one volt.


Electronic wire and cable- Wire or cable used in electronic applications.


Electrostatic - Pertaining to static electricity or electricity at rest. For example, an electric charge.


Electrostatic coupling - The transfer of energy by means of a varying electrostatic field. Capacitive coupling.


Electronic shuttering - Electronic shuttering is the ability of the camera to compensate for moderate light changes in indoor applications without the use of auto iris lenses.


Electronic wire and cable - Wire or cable used in electronic applications.


Electrostatic - Pertaining to static electricity, or electricity at rest. For example, a static electric charge.


Electrostatic coupling - The transfer of energy by means of a varying electrostatic field; capacitive coupling.


Electrostatic discharge (ESD) - An instantaneous flow of an electrical charge on a nonconductor through a conductor to ground.


Elexar - Shell trademark for a thermoplastic Elastomer (TPE).


Elfext (equal level far-end crosstalk) - A measure of the unwanted signal coupling from a transmitter at the near-end into a neighboring pair measured at the far-end relative to the received signal measured on that same pair. ELFEXT is FEXT-adjusted to discount attenuation.


Elongation - The fractional increase in the length of a material stressed in tension.


EMA (electrical moisture absorption) - A water tank test during which the sample cables are subjected to voltage while the water is maintained at rated temperature; the immersion time is long, with the object being to accelerate failure due to moisture in the insulation; simulates buried cable.


EMB - Effective modal bandwidth.


Embossing - Identification by means of thermal indentation that leaves raised lettering on the sheath material of cable.


Emergency overload - A situation in which larger than normal currents are carried through a cable or wire for a limited period of time.


EMF (electromotive force) - See VOLTAGE.


EMI (electromagnetic interference) - External signals that disrupt the data being transmitted on the local area network or electronic device being operated. Typically, these external signals emanate from universal motors with brushes, fluorescent lights, personal computers, printers or other devices including copy machines, etc. The Federal Communications Commission (FCC) regulates this emission area.


EMI/RFI filter - Circuit or device containing series inductive (load-bearing) and parallel capacitive (non-load-bearing) components that provide a low-impedance path around the protected circuit for high-frequency noise. Filters and surge suppressors when used together act synergistically.


Endosmosis - The penetration of water into a cable by osmosis; aggravated and accelerated by DC voltage on the cable.


Ends - In braiding, the number of essentially parallel wires or threads on a carrier.


Energize - To apply voltage to a circuit or device in order to activate it.


Entrance facility, telecommunications - An entrance to a building for both public and private
network service cables (including antennae) including the entrance point at the building wall and continuing to the entrance room or space.


Environment – (1) The universe within which a system must operate (2) All the elements over which the designer has no control and that affect a system or its puts and outputs.


EO - A UL cable type. Elevator lighting and control cable with thermoset insulation.


EOT (end of transmission character) - A transmission control character used to indicate the end of transmission, which may include one or more texts and any associated message headings.


EP, EPR, EPM, and EPFM - Designations for synthetic rubber based upon ethylene-propylene hydrocarbon.


EPA (Environmental Protection Agency) - The federal regulatory agency responsible for keeping and improving the quality of our living environment – mainly air and water.


EPDM (ethylene propylene diene monomer) - A rubber thermoset material with good insulating properties.


EPON - Ethernet passive optical network.


EPR - Ethylene propylene rubber.


EPROM (erasable programmable read-only memory) - A nonvolatile semiconductor PROM that can have three current contents cleared (usually through exposure ultraviolet light) and then accept new contents for storage.


Equalization - Equalization is achieved by circuitry that compensates for the differences in attenuation at different frequencies.


Equalizer - A device used by modems to compensate for distortions caused by telephone line conditions.


Equilay conductor - See CONCENTRIC-LAY CONDUCTOR.


Equipment grounding conductor - A conductor used to connect noncurrent-carrying metal enclosures of electrical equipment to the system ground.


Equipment room - The room in which voice and data common equipment are housed, protected and maintained, and where circuit administration is performed using the trunk and distribution cross-connects.


Equipment wiring subsystem - The part of a premises distribution system that includes the cable and distribution in an equipment room and that interconnects system-common equipment, other associated equipment and cross-connects.


ER rated - Exposed Run. An optional UL rating on UL Listed cable Types TC, ITC and
PLTC that meet the same crush and impact requirements as metal clad (Type MC) cables. Formerly called Open Wiring rated. Permits exposed runs between cable tray and utilization equipment.


Error detection - A hardware or software protocol determining when a group of incoming data has an error. If one is detected, the receiving modem orders the transmitting modem to resend the data group that contains the error.


Error rate - A measure of data integrity, given as the fraction of bits which are flawed. Often expressed as a negative power of 10, as in 10-6 (a rate of one error in every one million bits).


ESF - Extended super frame format.


ESCON - IBM Enterprise Systems Connection. A highly flexible channel interconnection environment with extended distance range, it combines technology and architecture including optical fiber cabling, dynamic connectivity, interconnectivity with other networks and input/output (I/O) architecture that exploits optical fiber.


ET - A UL cable type. Elevator lighting and control cable with thermoplastic insulation, three braids, flame-retardant and moisture-retardant finish. May have steel supporting strand in the center, 300 V.


Etched wire - A process applied to Teflon wire in which the wire is passed through a sodium bath to create a rough surface to allow epoxy resin to bond to the Teflon.


ETFE - (Tefzel) DuPont trademark for ethylene tetrafluoroethylene.


Ethernet - Ethernet is a network standard of communication using either coaxial or twisted-pair cable. The most widely used in LAN communications, Ethernet typically runs at 10 megabytes per second, though newer systems use 100 Mbps or 10 Gbps.


ETL - Electrical testing laboratory.


ETPC - Abbreviation for electrolytic tough pitch copper. It has a minimum conductivity of 99.9 percent.


ETPR (expanded thermal plastic rubber) - ETPR is often used as a filling compound in OSP cable.


EVA - Ethylene vinyl acetate. A polymer often used for the jacket in low smoke, zero halogen, flame retardant cables. Often referred to as a polyolefin.


Exchange - A unit established by a common carrier for the administration of communications services in a specified geographical area such as a city. It consists of one or more central offices together with the equipment used in providing the communications services. Frequently used as a synonym for central office.


Exit angle - The angle between the output radiation vectors and the axis of the fiber or fiber bundle.


Excitation losses - Losses in a transformer or electrical device because of voltage.


Expanded diameter - Diameter of shrink tubing as supplied. When heated the tubing will shrink to its extruded diameter.


Explicit access - In LAN technology, a shared access method that allows stations to use the transmission medium individually for a specific time period; every station is guaranteed a turn, but every station must also wait for its turn. Contrast with CONTENDED ACCESS.


Extension tube - Kit consisting of various size spacers that are used between the lens and the camera to reduce the lens MOD. Generally used for very close-up applications. Not recommended for zoom lenses due to loss of tracking.


External timing - Use of a timing source that is external to the transmission system. This timing source synchronizes the transit and receives circuits with a given facility.


External wiring - Electronic wiring that interconnects subsystems within the system.


Extruded cable - Cable that is insulated by applying insulation material in a continuous extrusion process.


Extrusion - A method of applying insulation to a conductor or jacketing to a cable. The process is continuous and uses rubber, neoprene or a variety of plastic compounds.

F

F connector - A standard 75-ohm connector used on coaxial cable.


F-number - The f-number indicates the brightness of the image formed by the lens, controlled by the iris. A smaller f-number means a brighter image.


F-stop - A term used to indicate the speed of a lens. The smaller the f-number, the greater is the amount of light passing through the lens.


F/UTP - Foil applied over unshielded twisted pairs.


Facility – (1) In general, a feature or capability offered by a system, item of hardware or software. (2) In Telco environments, line and equipment used to furnish ac completed circuit. See NETWORK FACILITIES.


Facility equipment room - A room or wiring closet used to store extended networking components that link one building with another building. These products include remote bridges and remote repeaters as well as X.25 gateways and Decent wide-area network routers.


Facsimile - The remote reproduction of graphic material: an exact copy.


Farad - A unit of capacitance when a difference of potential of one volt produces a displacement of one coulomb in a capacitor. The farad is a very large unit and a much smaller unit, the microfarad (μf), is more commonly used.


FAT (file allocation table) - A record, generated by DOS, that keeps track of where each file is on a disk, which sectors of the disk are in use and which sectors are available for new data to be written to them.


Fatigue resistance - Resistance to metal crystallization, which leads to conductors or wires breaking during flexing.


Fault - An unintentional, low-resistance connection between two or more conductors, or an open or broken conductor.


Fault ground - A fault to ground.


FCC (Federal Communications Commission) - Has the authority to regulate all interstate communications originating in the United States. It is run by seven board members appointed by the President. It sets prices for interstate phone, data and video service; determines who can or cannot get into the business of providing telecommunications service or equipment in the U.S.; and determines the electrical and physical standards for telecommunications equipment.


FDDI (fiber distributed data interface) - An ANSI defined token-passing ring using optical fiber media to attain a 100 Mbps transmission rate.


FDM (frequency division multiplexing) - Method by which the available transmission frequency range is divided into narrower bands, each used for a separate channel. As used by broadband technology, the frequency spectrum is divided up among discrete channels to allow one user or a set of users access to single channels.


FDMA - Frequency division multiple access.


FEXT (far-end crosstalk) - Unwanted signal coupling from a transmitter at the near end into a neighboring pair measured at the far end.


FDX (full-duplex) - Transmission in two directions simultaneously or, more technically, bi directional, simultaneous two-way communications.


Feeder cable - An intermediate cable distribution line in a broadband coaxial network that branches off a main trunk cable.


Femto - A prefix meaning 0.000000000000001 (10-15).


FEP - (Teflon) DuPont trademark for Fluorinated Ethylene Propylene. Front-end processor.


FEPB - A UL cable type. Fluorinated ethylene propylene insulated wire with glass braid. 14 AWG to 2 AWG, 90°C dry/damp or 200°C dry maximum operating temperature.


FDDI - Fiber distributed data interface.


FDM - Frequency division multiplexing.


FDX - Full duplex.


FEXT - Far-end crosstalk.


FFH-2 - A UL type of heat-resistant rubber-covered fixture wire with flexible stranding. 600 V rating, 18 AWG–16 AWG, 75°C maximum operating temperature.


Fiber dispersion - Pulse spreading in an optical fiber caused by differing transit times of various modes (a mode is one ray of light).


Fiber backbone - See BACKBONE.


Fiber optic cable - See OPTICAL FIBER.


Fiber optics - Transmission of energy by light through glass fibers. A technology that uses light as an information carrier. Optical fiber cables (light guides) are a direct replacement for conventional coaxial cable and wire pairs. The glass-based transmission cable occupies far less physical volume for an equivalent transmission capacity; the fibers are immune to electrical interference.


Fiber tubing - A loose, crush-resistant cylinder applied over individual fibers to provide mechanical protection. Also called a buffer tube.


Field - One half of a frame, consisting of either the odd or the even numbered lines, 60 fields are transmitted every second.


Field coil - A suitable insulated winding mounted on a field pole to magnetize it.


Field molded splice - A joint in which the solid dielectric joint insulation is fused and cured thermally at the job site.


Field tests - Tests that may be made on a cable system after installation as an acceptance or proof test. Various standards with test recommendations exist, like IEEE 400.


Figure 8 cable - An aerial cable configuration in which the conductors and the steel strands that supports the cable are integrally jacketed. A cross section of the finished cable approximates the figure "eight."


File - A collection of related data records.


File server - A station dedicated to providing file and mass data storage to the other stations on the local network.


Filled cable - A cable construction in which the cable core is filled with a material that will prevent moisture from entering or passing through the cable.


Filler - Fillers are used in multi-conductor cables that occupy the interstices formed by the assembled conductors. This is done so that the finished cable will be round.


Filling compound - A dielectric material poured or otherwise injected into a splice housing to prevent the entry of water. Filling compounds may require heating or mixing prior to filling. Some filling compounds may also serve as the insulation.


Filter - An arrangement of electronic components designed to pass signals in one or several frequency bands and to attenuate signals in other frequency bands.


Fine stranded wire - Stranded wire with component strands of 36 AWG or smaller.


Flame resistance - The ability of a material to not propagate flame once the heat source is removed.


Flammability - The measure of a material's ability to support combustion.


Flange black - The distance from the flange of the lens (beginning of the lens mount) to the focal plane. C mount lenses have a flange back distance of 17.526 mmv s. 12.5 mm for CS mount.


Flashover - A disruptive discharge around or over the surface of a solid or liquid insulator.


Flat braid - A woven braid of tinned copper strands rolled flat at the time of manufacture to a specified width.


Flat cable - A cable with two essentially flat surfaces.


Flat conductor - A wire having a rectangular cross section as opposed to a round or square conductor.


Flat loss - Equal signal loss across the system's entire bandwidth.


Flex-life - The measurement of the ability of a conductor or cable to withstand repeated bending usually specified as expected total number of cycles before failure.


Flexibility - The ease with which a cable may be bent. In general, finer stranding gives greater flexibility. Various types of cables are available depending on the type of flexing required.


Flexible - That quality of a cable or cable component that allows for bending under the influence of an outside force, as opposed to limpness that is bending due to the cable's own weight.


Floating - Refers to a circuit that has no electrical connection to ground.


Flooded cable - A special coaxial cable that contains a corrosion resistant gel between the outer aluminum sheath and the outer jacket. The gel flows into imperfections in the jacket to prevent corrosion in high-moisture areas.


Flow control - The capability of network nodes to manage buffering schemes in order to allow devices of differing data transmission speeds to communicate with each other.


Fluoropolymer - A class of polymers used as insulating and jacketing materials. Common ones include Teflon, Tefzel, Kynar and Halar.


Flux - (1) The lines of force which make up an electrostatic field. (2) The rate of flow of energy across or through a surface. (3) A substance used to promote or facilitate fusion, commonly used in soldering.


FM (frequency modulation) - A modulation technique in which the carrier frequency is shifted by an amount proportional to the value of the modulating signal. The amplitude of the carrier signals remains constant. The deviation of the carrier frequencies determines the signal content of the message.


Foamed insulation - Insulations having a cellular structure.


Focal length - The distance from the center of the lens to a plane at which point a sharp image of an object viewed at an infinite distance from the camera is produced. The focal length determines the size of the image and the angle of the field of view seen by the camera through the lens. That is the distance from the center of the lens to the pickup device.


Focis - Fiber Optic Connector Intermateability Standard.


Foil - A thin, continuous sheet of metal. Often used as a shield material in cables.


FOIRL (Fiber Optic Inter-Repeater Link) - An optical fiber signaling methodology based in the proposed IEEE 802.3 standard governing optical fiber and the FDDI standard.


Foot-candle – It is the light intensity (illumination) of a surface one foot distant from a source of one candela. It is equal to one lumen per square foot. (1FC = 1 lmf t.2). The foot-candle is the unit used to measure incident light.


Forward direction - The direction on the cable from the head end to the modems.


Four-wire circuit, four-wire line - A circuit using two pairs of conductors, one pair for the transmit channel and the other pair for the receive channel. All long distance circuits are four-wire. Almost all local phone lines are two wires. All analog phones are two wires. Four-wire circuits offer much higher quality.


Frame - 1. The total area of the picture that is scanned while the picture signal is not blanked. 2. Same as transmission block. 3. The sequence of bits and bytes in a transmission block. 4. The overhead bits and bytes that surround the information bits in a transmission block. 5. The unit of transmission in some local area networks, including the IBM token-ring network. It includes delimiters, control characters, information and checking characters. A frame is created from a token when the token has data appended to it.


Framing - Process of inserting control bits to identify channels; used in TDM signals.


Frequency - The number of cycles per second, at which an analog signal occurs, expressed in hertz (Hz). One hertz is one cycle per second.


Frequency analyzer - An instrument to measure the intensity of various component frequencies from a transmitting source.


Frequency counter - An electronic measuring instrument that precisely counts the number of cycles of a periodic electrical signal during a given time interval.


Frequency deviation - A swing away from the nominal frequency.


Frequency division multiplexing - The splitting of a communications line into separate frequency bands, each capable of carrying information signals. This allows several messages to be sent at the same time over the same transmission medium.


Frequency Modulation (FM) - Method of encoding a carrier wave by varying the frequency of the transmitted signal.


Frequency plan - Specification of how the various frequencies available in a communications system are allocated for use. In the U.S. the FCC defines uses for various frequency bands.


Frequency range - The frequency spectrum allocated for use by any frequency selective device or component.


Frequency response - The variation of gain or attenuation with frequency.


Front porch - The portion of the composite video signal that lies between the leading edge of the horizontal blanking pulse and the leading edge of the corresponding synchronizing pulse.


FSMA (fiber subminiature assembly) - It is a threaded connector for multimode optical fiber cables.


FSO (free space optics) - Refers to the transmission of modulated visible or infrared (RI) beams through the atmosphere to obtain optical communications. Like fiber, free space optics (FSO) uses lasers to transmit data, but instead of enclosing the data stream in a glass fiber, it is transmitted through the air.


FTTD® - Anixter registered trademark meaning fiber to the desk.


FTTH - Fiber to the home.


FTTP - Fiber to the premises.


Full duplex - Two-way communications in which each modem simultaneously sends and receives data at the same rate.


Fuse wire - Wire made from an alloy that melts at a relatively low temperature to open a circuit when over-current conditions occur.


Fused coating - A metallic coating that has been melted and solidified, forming a metallurgical bond to the base material.


Fused conductors - Individual strands of heavily tinned copper wire stranded together and then bonded together by induction heating.


Fused spiral tape - A PTFE insulation often used on hook-up wire. The spiral wrapped tape is passed through a sintering oven where the overlaps are fused together.

G

G - A UL portable power cable type with thermoset insulation and thermoset fiber reinforced oil-resistant jacket. Two to five #8 AWG or larger conductors with ground wires. Rated 2,000 V, 60°C maximum operating temperature when exposed to oil, 90°C maximum dry.


G-GC - A UL cable type. A portable power cable similar to Type G, but also having a ground check (GC) conductor to monitor the continuity of the grounding circuit.


Gain - The increase in signaling power caused by an amplifier and measured in decibels (dB).


Galvanized steel wire - Steel wire coated with zinc.


Gang strip - Stripping all or several conductors simultaneously.


Gas discharge tube - 1. A calibrated spark gap in a gas-filled chamber. These devices are relatively slow, activating in microseconds, but can handle very large surges. They work by shunting the surge or spike impulse around the protected circuit. 2. A method of protecting phone lines and phone equipment from high voltage caused by lightning strikes.


Gas filled cable - A self-contained pressurized cable in which the pressure medium is an inert gas having access to the insulation.


Gateway - Provides a convenient way to create a local network. It works as a combined router, switch and a NAT (network address translator) and is available from various manufacturers.


Gauge - A term used to denote the physical size of a wire. See AWG.


Gauss - A unit of magnetic induction (flux density) equal to 1 Maxwell lper cm2 or 10-4 weber per meter2.


General purpose instrumentation bus (GPIB) - A protocol standard defined by the IEEE. Often used on automated test and measurement equipment in manufacturing environments.


Gen-lock - A method used to synchronize one or more cameras by external means such as composite video, composite sync, horizontal or vertical sync.


GFCI - Ground fault circuit interrupter. A protective device that detects abnormal current flowing to ground and then interrupts the circuit. Required by the NEC for some installations.


GFI (ground fault interrupter) - A protective device that detects abnormal current flowing to ground and then interrupts the circuit.


Ghost - A shadowy or weak image in the received picture, offset either to the right or to the left of the primary image. It is the result of transmission conditions where secondary signals are created and received earlier or later than the primary signal.


GHz (gigahertz) - 1,000,000,000 cycles per second.


GIGA - A numerical prefix denoting one billion (109).


GLAND - A device used to terminate, seal and/or ground the metallic armor of a cable as it enters a metal enclosure. Sometimes called a fitting or a connector.


GND - Common abbreviation for ground.


GPRS (general packet radio service) - Wireless (cellular) telephony.


Graded index fiber - An optical fiber with a refractive index that gets progressively lower away from the axis. This causes the light rays to be continually refused by refraction in the core. It 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.


Green goop - A viscous liquid that occasionally oozes from the end of installed PVC cables after many years in service. Generally found to be plasticizer (a component of PVC) contaminated with a copper compound that is green in color.


Ground - A voltage reference point that is the same as earth or chassis ground.


Ground check conductor (GC) - An insulated conductor commonly used in mining cables to monitor the health of the grounding conductor(s) in the cable.


Ground conductor - A conductor in a transmission cable or line that is grounded.


Ground fault - See FAULT GROUND.


Ground loop - Caused by different earth potentials in a system. Affects video pictures in the form of a black shadow bar across the screen or as a tearing in the top corner of a picture.


Ground plane - Expanded copper mesh that is laminated into some flat cable constructions as a shield.


Ground potential - Zero potential with respect to the ground or earth.


Grounded neutral - The neutral wire that is metallically connected to ground.


GTO - Gas tube sign cable, UL Listed as single conductor Type GTO-5 (5,000 V), GTO-10 (10,000 V) or GTO-15 (15,000 V), in sizes 18-10 AWG copper. This cable is intended for use with gas tube systems for signs, outline lighting, and interior lighting.


Guard band - 1. The unused bandwidth separating channels to prevent crosswalk in an FDM system. 2. In a broadband system, the frequency spectrum between the inbound and outbound pass bands.


GSM (global system for mobile communications) - A type of wireless (cellular) telephony.


GUI (graphical user interface) - Computer "human interface" that is based on icons rather than text. Pioneered by Xerox, implemented first by Apple, then by Microsoft Windows, Hewlett Packard and Unix-X-Windows.


Guy - A tension wire connected to a tall structure and another fixed object to add strength to the structure.

H

Halar (ECTFE)  - Ausimont Co. trademark for Ethylene ChloroTriFluoro Ethylene.


Half-duplex - Two-way communications in which data are sent in only one direction at a time.



Halogenated  - Containing halogen atoms such as chlorine, fluorine, bromine or iodine.



Halogens  - Chemical elements such as chlorine and bromine that when present in a cable are released when burned. These materials can cause damage to human respiratory systems and to electrical equipment.



Hard-drawn wire - As applied to aluminum and copper, wire that has been cold drawn to final size so as to approach the maximum strength attainable.



Hardware handshaking  - The ability of a modem to signal when to start or stop transmitting data. Handshaking is accomplished by sending a control signal over the modem cable rather than by issuing a software command.



Harmonic distortion  - A form of interference involving the generation of unwanted signals.



Harmonic  - Sinusoidal component of an AC voltage that is multiple of the fundamental waveform frequency.



Harness  - An arrangement of wires and cables, usually with many breakouts, which have been tied together or pulled into a rubber or plastic sheath, used to interconnect an electric circuit.



Harsh mark stripe  - A non-continuous helical stripe applied to a conductor for identification.



Hazardous location  - Ignitable vapors, dust, or fibers that may cause fire or explosion as defined by the NEC.



HC  - Horizontal cross-connect.



HDCP (high-definition content protection) - A type of digital encryption that protects content from being copied. A subsystem of HDMI.



HDMI (high-definition multimedia interface) - The newest digital video connection on the market. HDMI supports the same high-quality video as DVI; however, it also incorporates digital audio support at many rates including surround sound, copyright protection and consumer control, all packaged into a cable with a connector about half the physical size of the original DVI connector. Utilizes a 19 pin plug for single link DVI or a 29 pin plug for dual link DVI. Works up to 75 ft. (23 m).



HDPE  - High-density polyethylene.



HDTV  - High-definition television.



HDX (half-duplex transmission) - Transmission in either direction but not in both directions simultaneously. Compare with FULL DUPLEX.



Headend unit  - In LAN technology, an item of hardware on a single or dual cable broadband network using split frequency bands to provide multiple services.



Headend (Head-end) - A central point in broadband networks that receives signals on one set of frequency bands and retransmits them on another set of frequencies.



Heat distortion  - Distortion or flow of a material or configuration due to the application of heat.



Heat seal  - Method of sealing a tape wrap jacket by means of thermal fusion.



Heat shock  - A test to determine stability of material by sudden exposure to a high temperature for a short period of time.



Heat sink  - A device that absorbs heat.



Heater cord  - A group of cable types defined in Article 400 of the NEC such as types HPD, HPN, HS, HSJ, HSJO and HSO.



Helical stripe  - A continuous, colored, spiral stripe applied to a conductor for circuit identification.



Helix  - Spiral winding.



Henry  - A unit of inductance equal to the inductance of a current changing at the rate of one ampere per second inducing a counter electromotive force of one volt.



Hertz (Hz)  - Cycles per second. A cycle that occurs once every second has a frequency of 1 hertz.



HF  - High frequency.



HID  - High-intensity discharge, mercury metal halide and sodium lamps.



High bond insulation  - Insulation exhibiting great bond strength to the conductors.



High-split - A broadband cable system in which the bandwidth used to send toward the head-end (reverse direction) is approximately 6 MHz to 180 MHz and the bandwidth used to send from the head-end (forward direction) is approximately 220 MHz to 400 MHz The guard band between the forward and reverse directions (180 MHz to 220 MHz) provides isolation from interference.



High-temperature water and cable - Electrical wire and cables that have maximum operating temperatures of 150°C and higher.



High-tension cables - Generally unshielded high-voltage ignition wires for combustion engines, gas and oil igniters, neon signs, etc. Usually Type GTO.



High-voltage cable termination - A device used for terminating alternating current power cables having laminated or extruded insulation rated 2.5 kV and above.



High-voltage power (system voltage ratings) - A class of system voltages equal to or greater than approximately 69,000 volts or less than 230,000 volts.



Hinge cable  - A cable connected between a hinged or swinging device and a stationary object.



HIPAA (Health Insurance Portability and Accountability Act [1996])  - HIPAA provides rights and protections for participants and beneficiaries in group health plans. This can include protections for electronic transmission of health information.



Hipot  - A DC high-potential test used on medium- and high-voltage cables. See DIELECTRIC STRENGTH TESTING.



HI-Z (un-terminated) - Video input of a piece of CCTV equipment, wired so as to allow the video signal to be fed to further equipment. Does not necessarily include extra sockets for the extra coaxial cables.



HL  - Hazardous location. An optional rating for UL Listed Type MC cables. Article 501 of the NEC permits Type MC-HL Listed cables to be used in Class I, Division 1 Hazardous Locations.



HMWPE  - High-molecular weight polyethylene.



Holding strength  - Ability of a connector to remain assembled to a cable when under tension.



Hook up wire  - Small wires used to hook up instruments or electrical parts, usually 12 AWG and smaller.



Horizontal (HUM) bars  - Horizontal bars, alternately black and white, which extend over the entire picture. They are known as venetian-blinds. They may be stationary or move up or down. They are often caused by approximately 60 hertz interfering frequency or its harmonic frequencies.



Horizontal blanking  - The blanking signal that is produced at the end of each scanning line.



Horizontal cross-connect - A cross-connect of horizontal cabling to other cabling, e.g., horizontal, backbone, equipment.



Horizontal resolution  - The maximum number of individual picture elements that can be distinguished in a single scanning line.



Horizontal subsystem  - The part of a premises distribution system installed on one floor that includes the cables and distribution components connecting the riser subsystem and equipment wiring subsystem to the information outlet via cross-connects.



Hot modulus  - Stress at 100 percent elongation after 5 minutes of conditioning at a given temperature (normally 130°C).



Hot stamping  - Method of alphanumeric coding. Identification markings are made by pressing heated tape and marking foil into softened insulation surfaces.



Hot stick - A long insulated stick having a hook at one end that is used to open energized switchgear, high-voltage equipment, etc. Allows safe separation of user and high-voltage source.



Hot tin dip  - A process of passing bare wire through a bath of molten tin to provide a coating.



Housing  - A metallic or other enclosure for an insulated splice.



HPD  - A UL portable heater cord type. 300 V rating with two, three or four 18-12 AWG conductors with thermoset insulation and a cotton or rayon outer covering. For use in dry, no hard use locations, minimum maximum operating temperature of 90°C.



HPN  - A UL portable heater cord type with parallel construction. 300 V rating with two or three 18-12 AWG conductors. Oil-resistant thermoset insulation and jacket. For use in no hard usage and damp locations, minimum maximum operating temperature of 90°C.



HRC (harmonically related carrier)  - In CATV, an offset band of channel frequencies.



HSJO  - A UL thermoset jacketed heater cord type. 300 V rating with two, three, or four 18-12 AWG conductors. Oil-resistant thermoset insulation and jacket. For use in non-hard usage and damp locations, minimum maximum operating temperature of 90°C.



HSPD (Homeland Security Presidential Directive)  - Various directives related to security.



HSPD-12 - Requires a common ID credential for all federal employees and contractors to be used for both physical access to facilities and logical access to information systems. The PIV (personal identity verification) standard requires contact and contactless smart card technologies and biometrics.



HSRP  - Hot standby router protocol.



HTCP  - Home theater personal computer, separates the computer and its keyboard.



HTML (Hypertext Markup Language)  - HTML is the major language of the Internet's World Wide Web. Web sites and Web pages are written in HTML. With HTML and the World Wide Web, you have the ability to bring together text, pictures, sounds and links. HTML files are plain text files, so they can be composed and edited on any type of computer.



HTTP (Hypertext Transfer Protocol)  - It's the network protocol used to deliver virtually all files and other data (collectively called resources) on the World Wide Web, whether they're HTML files, image files, query results or anything else. Usually, HTTP takes place through TCP/IP sockets. A browser is an HTTP client because it sends requests to an HTTP server (Web server), which then sends responses back to the client. The standard (and default) port for HTTP servers to listen on is 80, though they can use any port.



Hub  - In LAN technology, it is 1. The center of a star topology network or cabling system; and 2. Same as a head end for bi-directional networks except that it is more centrally located within the network.



HV  - High voltage.



HVAC  - Heating, ventilation and air conditioning.



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



Hybrid network  - A LAN with a mixture of topologies and access methods. For example, a network that includes both a token ring and a CSMA/CD bus.



Hybrid topology  - A network interconnection scheme consisting of a mixture of elements of daisy chain, fully connected, hierarchical, ring and star topologies.



Hydroscopic  - Readily absorbing and retaining moisture.



Hypalon  - (CSP) DuPont trademark for chlorosulphonated polyethylene.



HYPOT  - Registered trade name of Associated Research, Inc. for its high-voltage tester. See HIPOT.



Hysteresis  - The time lag between transitions in state exhibited by a body while reacting to changes in applied forces.



Hz (hertz)  - A measure of frequency or bandwidth equal to one cycle per second. Named after experimenter Heinrich Hertz.

I

I  - Symbol used to designate current. From the French word for current intensity (intensite du courant).


I/O (input/output)  - The process of transmitting data to and from the processor and its peripherals.



I2R  - Formula for power in watts, where l=current in amperes, R=resistance in ohms.



I2R  - Formula for power in watts, where l = current in amperes, R = resistance in ohms. See WATT.



IACS  - International Annealed Copper Standard for copper used in electrical conductors. 100 percent conductivity at 20°C is 0.017241 ohm-mm2/m.



IAD  - Integrated access device.



IC  - Intermediate cross connect.



ICEA (Insulated Cable Engineers Association)  - The association of cable manufacturing engineers who make nationally recognized specifications and tests for cables. Formerly IPCEA.



IDC  - Insulation displacement connector.



IDE  - Integrated drive electronics also known as ATA (advanced technology attachment).



IDF  - Intermediate distribution frame.



IDMS (identity management system)  - A system that manages the identities and privileges of computer systems and people. Can be used in conjunction with both physical and IT access control.



IDS (intrusion detection system)  - A system that monitors network traffic and responds with an alarm when it detects port scanning, an unauthorized access attempt, a denial-of-service attack or other forms of attack on the network.



IEC  - International Electrotechnical Commission.



IEEE (Institute of Electrical and Electronic Engineers)  - An international professional society that issues its own standards and is a member of ANSI and ISQ.



IEEE 10BASE2 network  - A network conforming to the IEEE 802.3 local area network standard. The network is capable of carrying information at rates up to 10 Mbps over distances up to 185 meters; also called thin net.



IEEE 10BASE5  - A network conforming to the 8023 local area network standard. The network is capable of carrying 10 Mbps of data over coax cable for distances up to 500 meters.



IEEE 10BROAD36  - 10 million bits per second over broadband coaxial cable with node-to-node coverage of 3,600 meters. The IEEE 802.3 specification for running Ethernet on broadband.



IEEE 488 (Institute of Electrical And Electronic Engineers - 488) - An IEEE standard parallel interface bus consisting of eight bi-directional data lines, eight control lines and eight signal grounds, which provide connections to an IEEE-488 device.



IEEE 488 241C gen. interface bus cable assembly  - Meets the requirements of IEEE 488 standard for cable interface of up to 15 programmable instruments in a BUS-connected system. Dual-sided connector can terminate into a star or daisy chain.



IEEE 802  - Standards for the interconnection of local networking computers equipment. The IEEE-802 standard deals with the physical link layers of the ISO Reference Model for OSI.



IEEE 802.1  - The standard that defines the network layer of the OSI Model for LANs. IEEE 802.1d defines the spanning tree protocol (STP) used by bridges to detect and break any loops found in an Ethernet network.



IEEE 802.11  - Wireless LAN standard.



IEEE 802.15  - Wireless PAN. (Bluetooth)



IEEE 802.2  - A subcommittee responsible for defining the upper half of the data link layer, known as the LLC or logical link control.



IEEE 802.3  - An IEEE standard describing the physical and data link layers of a local area network based on bus topology and CSMA/CD. (Ethernet)



IEEE 802.3af  - Data terminal equipment (DTE) power delivery standard. Commonly referred to as Power over Ethernet (PoE).



IEEE 802.4  - A physical layer standard specifying a LAN with a token-passing access method on a bus topology. Used with manufacturing automation protocol LANs.



IEEE 802.5  - A physical layer standard specifying a LAN with a token-passing access method on a ring topology. Used by IBM's token ring hardware.



IEEE 802.6  - The IEEE project 802 LAN Standards for Empty Slot Ring. A ring LAN in which a free packet circulates past, or more precisely, through every station; a bit in the packet's header indicates whether it contains any messages (if it contains messages, it also contains source and destination addresses).



IEEE 802.7  - A proposed physical layer standard specifying a LAN using both 802.3 and 802.4 standards.



IEEE 802.8  - The IEEE Project 802 committee responsible for defining standards for optical fiber LANs.



IEEE 802.g  - A committee looking into aspects of ISDN type voice and data integration across IEEE 802.3 and 802.4 LANs. As yet, the IEEE 802.9 committee has made "proposals," but has not published any "standards."



IEEE-488 - An IEEE standard for a parallel interface bus consisting of eight bidirectional data lines, eight control lines and eight signal grounds, which provides for connection to an IEEE-488 device.



IETF  - Internet Engineering Task Force.



IF  - Intermediate frequency.



IGMP (Internet Gateway Multicast Protocol)  - A standard IP protocol. When used in MAPs it is the signaling mechanism used with multicasting of video. The set-top box uses IGMP to insert or remove a subscriber from a video stream (IGMP multicast filtering).



Image size  - Reference to the size of an image formed by the lens onto the camera pickup device. The current standards are 1 in., 2/3 in., 1/2 in. and 1/3 in. measured diagonally.



IMAP  - Internet Message Access Protocol.



Impact tests  - Tests designed to reveal the behavior of material of a finished part if it were subjected to impact or shock loading.



Impairment  - The generic term for a flaw in phone line quality, usually caused by echo, noise or a reduction in signal strength.



Impedance match  - A condition whereby the impedance of a particular cable or component is the same as the impedance of the circuit, cable, or device to which it is connected.



Impedance matching stub  - A section of transmission line or a pair of conductors cut to match the impedance of a load. Also called matching stub.



Impedance matching transformer  - A transformer designed to match the impedance of one circuit to that of another.



Impedance  - The total opposition a circuit, cable or component offers to alternating current. It includes both resistance and reactance and is generally expressed 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. When connected across the cable's output terminals; the impedance that makes a transmission cable seems infinitely long. For a waveguide, when the waveguide is match-terminated, it is the ratio of rms voltage to total rms longitudinal current at certain points on a diameter.



Impulse  - See PULSE.



IMSA  - International Municipal Signal Association.



In-band signaling - The transmission of signaling information at some frequency or frequencies that lie within a carrier channel normally used for information transmission.



Incident light  - The light that is falling directly over an object.



Incoherent source  - A fiber optic light source that emits wide, diffuse beams of light of many wavelengths.



Index edge  - Edge of a flat (ribbon) cable from which measurements are made, normally indicated by the location of the printing which is near the index edge. Sometimes indicated by a thread or other identification stripe.



Indoor termination  - A cable termination intended for use where it is protected from direct exposure to both solar radiation and precipitation.



Inductance  - A property of a conductor or circuit that resists a change in current. It causes current changes to lag behind voltage changes and is measured in henrys.



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 I2R losses account for the resultant heat.



Induction  - The phenomenon of a voltage, magnetic field or electrostatic charge being produced in an object by lines of force from the source of such fields.



Inductive coupling  - Crosstalk resulting from the action of the electromagnetic field of one conductor on the other.



Industrial Ethernet cables  - Cables specially designed to withstand the mechanical, chemical and electrical rigors of an industrial environment. Widely used in industrial process control networks.



Infrastructure telecommunications  - A collection of those telecommunications components, excluding equipment, that together provide the basic support for the distribution of all information within a building or campus.



Input  - A signal (or power) that is applied to a piece of electric apparatus, or the terminals on the apparatus to which a signal or power is applied.



Insertion loss  - The signal strength loss that occurs when a piece of equipment is inserted into a line.



Insertion tool  - A small, hand-held tool used to insert contacts into a connector.



Inside plant  - Everything inside a telephone company central office. See INSIDE WIRING.



Inside wiring  - The telephone wiring located inside your premises or building. Inside wiring starts at the telephone company's demarcation point and extends to the individual phone extensions. Traditionally, inside wiring was installed and owned by the telephone company. Now you can install your own wiring. Most companies installing new phone systems are installing their own new wiring because of potential problems with reusing old telephone company cable.



Insulated radiant heating wire  - Similar to blanket wire but heavier construction for applications such as in ceiling panels, buried in ground or driveway and concrete walks.



Insulated splice  - A splice with a dielectric medium applied over the connected conductors and adjacent cable insulation.



Insulating (isolating) joint  - A cable joint that mechanically couples and electrically separates the sheath, shield and armor on contiguous lengths of cable.



Insulation level  - A thickness rating for power cable insulation. Circuits having fault detectors that interrupt fault currents within one minute are rated 100 percent level, within one hour are rated 133 percent level and over one hour are rated 173 percent level.



Insulation stress  - The potential difference across an insulator. The stress on insulation is expressed in volts per mill (V/m) or kilovolts per meter (kV/m).



Insulation temperature rating  - A maximum temperature assigned to insulations based on laboratory tests.



Insulation thickness  - The wall thickness of wire insulation.



Insulation voltage radiant  - The nominal phase-to-phase operating voltage of a three-phase cable system.



Insulation  - A material having good dielectric properties that is used to separate close electrical components, such as cable conductors and circuit components.



Insulation resistance  - The electrical resistance of an insulating material at a specific time and condition as measured between two conductors.



Intel  - A semiconductor (chip) manufacturer; one of the sponsors of Ethernet.



Intelligence, intelligent  - A term for equipment (or a system or network) that has a built in processing power (often furnished by a microprocessor) that allows it to perform sophisticated tasks in accordance with its firmware.



Interaxial spacing  - Center-to-center conductor spacing in paired wire or center-to-center spacing between conductors in a flat cable.



Intercalated tapes  - Two or more tapes helically wound and overlapped on a cable.



Interconnect  - A connection scheme that provides for the direct connection of individual cables to another cable or to an equipment cable.



Interconnecting cable  - The wiring between modules, units or the larger portions of a system.



Interconnection  - The joining of devices mechanically to complete an electrical circuit.



Interface device  - A device which meets a standard electrical interface on one side and meets some other nonstandard interface on the other. The purpose of the device is to allow a device with a nonstandard interface to connect to a device with a standard interface.



Interface  - 1. A shared boundary defined by common physical interconnection characteristics, signal characteristics and meanings of interchanged signals. 2. The equipment that provides this shared boundary.



Interference  - Disturbances of an electrical or electromagnetic nature that introduce undesirable responses into other electronic equipment.



Interlace  - A scanning process where every other horizontal line is scanned in one field while the alternate lines are scanned in the next field to produce a complete picture frame.



Interleaving  - A method used in alarms or activity detection that allows extra frames of video from alarmed cameras to be added to a time multiplexed sequence whilst a state of alarm exists.



Intermediate cross-connect - A cross-connect between first level and second level backbone cabling.



Intermediate frequency  - A frequency to which a signal is connected 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.



Intermediate temper  - As applied to aluminum, any temper between soft and hard drawn.



Internal wiring  - Electronic wiring that interconnects components, usually within a sealed subsystem.



Internetwork router  - In LAN technology, a device used for communications between sub networks; only messages for the corrected sub network are transmitted by this device.



Internetwork  - Between two distinct networks.



Interstice  - The space or void between assembled conductors and within the overall circumference of the assembly.



Intranet  - Within one network.



Intrinsically safe  - Incapable of releasing sufficient electrical or thermal energy under normal or abnormal conditions to cause ignition of a specific hazardous atmospheric mixture in its most ignitable concentration.



Ionization factor  - This is the difference between percent dissipation factors at two specified values of electrical stress; the lower of the two stresses is usually so selected that the effect of the ionization on dissipation factor at this stress is negligible.



Ionization voltage  - The potential at which a material ionizes. The potential at which an atom gives up an electron.



Ionization  - 1. The creation of ions when polar compounds are dissolved in a solvent. 2. When a liquid, gas or solid is caused to lose or gain electrons due to the passage of an electric current.



IP (Internet Protocol)  - A procedure used to forward Internet traffic to neighbor gateway nodes. IP is also used in ADS gateway nodes to forward traffic between networks. IP's primary function is Internet routing and packet fragmentation and assembly.



ipAssuredSM  - An infrastructure assurance program that matches the cabling infrastructure to the security equipment based on the technical, application and life-cycle requirements of the user.



IP-Class 1+SM - An Anixter ipAssured infrastructure cabling assurance that will meet life-cycle requirements of 1 to 5 years.



IP-Class 10+SM - An Anixter ipAssured infrastructure cabling assurance that will meet life-cycle requirements of 10 or more.



IP-Class 5+SM - An Anixter ipAssured infrastructure cabling assurance that will meet life-cycle requirements of 5 to 10 years.



Ips  - In video, it stands for images per second. It is also sometimes called pictures per second (pps).



IR drop - A method of designating a voltage drop in terms of both current and resistance.



IR drop  - A method of designating a voltage drop in terms of both current and resistance.



IRC (incrementally related carrier)  - In CATV, an offset band of channel frequencies.



IRE  - Institute of Radio Engineers.



Irradiation  - In insulations, the exposure of the material to high-energy emissions for the purpose of favorably altering the molecular structure.



ISDN (Integrated Services Digital Network)  - A CCITT standard that covers a wide range of data communication issues but primarily the total integration of voice and data. Digital phone lines that allow transmission of video signals via fast scan at speeds of 128 kbps; used with terminal adapters.



ISI (inter symbol interference)  - In multimode fiber it is caused by DMD (differential mode delay).



ISM (industrial, scientific and medical)  - Usually used to define the unlicensed RF bands used for wireless transceivers as defined by FCC regulations (47CFR parts 15 and 18). These are 5.8 GHz, 2.4 GHz and 900 MHz.



ISO (International Organization for Standardization)  - Reference model for open systems interconnection; a standard approach to network design that introduces modularity by dividing the complex set of communications protocols into more manageable, functional slices.



ISO 9000  - A set of quality standards widely used around the world.



ISO Reference Model for OSI (International Organization for Standardization Reference Model for Open Systems Interconnection)  - A standard approach to network design which introduces modularity by dividing the complex set of functions into more manageable, self-contained, functional slices. These layers, from the innermost layers, are as follows: 1. Physical Layer: Concerned with the mechanical and electrical means by which devices are physically connected and data are transmitted. 2. Link Layer: Concerned with how to move data reliably across the physical data link. 3. Network Layer: Provides the means to establish, maintain, and terminate connections between systems; concerned with switching and routing of information. 4. Transport Layer: Concerned with end-to-end data integrity and quality of service. 5. Session Layer: Standardizes the talk of setting up a session and terminating it; coordination of interaction between end-application processes. 6. Presentation Layer: Relates to the character set and data code which is used, and to the way data is displayed on a screen or printer. 7. Application Layer: Concerned with the higher level functions which provide support to the application of system activities.



Isochronous  - A form of data transmission in which individual characters are only separated by a whole number of bit-length intervals. Contrast with ASYNCHRONOUS in which the characters may be separated by random-length intervals. A form that will not tolerate delay. (e.g., Real-time V.V.)



Isolation loss  - The amount of signal attenuation of a passive device from output port to tap outlet port.



Isolation  - The ability of a circuit or component to reject interference, usually expressed in dB.



ITU  - International Telecommunications Union.



IW  - Inside wire.



IWCA  - Inside wiring cable.

J

Jabber (watchdog timer) - Built into controller units and transceiver units.


Jabber, jabbering - In LAN technology, continuously sending random data (garbage); normally used to describe the action of a station (whose circuitry or logic has failed) that locks up the network with its incessant transmission.


Jack - A plug-in type terminal widely used in electronic apparatus for temporary connections.


Jacket - Pertaining to wire and cable, the outer sheath that protects against the environment and may also provide additional insulation.


Jam - A short encoded sequence emitted by a node to ensure that all other nodes have detected a collision.


Jan specification - Joint Army-Navy specification (replaced by current military specifications).


JBOD (just a bunch of disks) - Used to refer to hard disks that aren't configured according to RAID; a subsystem of disk drives that improves performance and fault tolerance.


Jet starter cable - Single conductor 600 V cable used for external aircraft power.


Jitter - The slight movement of a transmission signal in time or phase that can introduce errors and loss of synchronization in high speed synchronous communications.


Joint - That portion of the conductor where the ends of two wires, rods or groups of wires are joined by brazing, soldering, welding or by mechanical means.


Joule - A unit of energy defined as the work done when the point of application of one Newton is displaced one meter in the direction of the force.


Joule's law - When electricity flows through a material the rate of heating in watts will equal the resistance of the material in ohms times the square of the current in amperes. W = I2R.


Jumper - 1. A wire used to connect equipment and cable on a distributing frame. 2. When errors are found on printed circuit boards, a jumper cable is sometimes soldered in to correct the problem.


Jumper cable - Extra flexible cables with high-voltage insulation for use as temporary connections. Usually has a red jacket.


Jumper wire - A short length of wire to route a circuit by linking two cross-connect termination points.


Junction box - Metal box inside which cables are connected together.

K

Kapton - DuPont trademark for polyimide.


kB (kilobyte) - 1,024 bytes. Usually describes bits or bytes, as in transmission speeds measured in kBsec or kilobits per second.


KBps - Kilobits per second.


Kcmil - One thousand circular mils, replaced "MCM" in the 1990 NEC. Sometimes shortened to "kcm."


Kevlar - A high-strength DuPont polymer used as a cable messenger or strength member.


Keying - The mechanical feature of a connector system that guarantees correct orientation of a connection or prevents the connection to a jack or to an optical fiber adapter of the same type intended for another purpose.


K-fiber - A polyaramid-based material used for jacketing high-temperature cables.


Khz - Kilohertz (1,000 hertz).


Kilo - Prefix meaning thousand.


KPSI - A unit of tensile strength expressed in thousands of pounds per square inch.


KS - Connecting a CATV trunks hard line.


kV (kilovolt) - 1,000 volts.


kVA - Kilovolt ampere.


kW (kilowatt) - 1,000 watts.


Kynar - Arkema Inc. trademark for polyvinylidene fluoride (PVDF).

L

L - Symbol for inductance.


Lacing and harnessing - A method of grouping wires by securing them in bundles of designated patterns.


Lacquer - A liquid resin or compound applied to textile braid to prevent fraying, moisture absorption, etc.


Lag - The image retention of an object after the object has been scanned. Sometimes, it causes smearing effect.


Lambda - Individual wavelengths as a result of DWDM.


Laminated tape - A tape consisting of two or more layers of different materials bonded together.


LAN (local area network) - A user-owned, user-operated, high-volume data transmission facility connecting a number of communicating devices within a single building or campus of buildings.


Laser (light amplification by stimulated emission of radiation) - A device that produces coherent light with a narrow range of wavelengths


Laser diode - A semiconductor diode that emits coherent light.


Laser-optimized multimode fiber (LOMMF) - Laser-optimized 50-micron multimode fiber. Uses an enhanced bandwidth capable of supporting 10 Gigabit Ethernet at 850 nm using VCSEL technology. This is also a restricted mode launch, so it avoids the pulse spreading due to DMD. Also referred to as OM3-grade fiber.


LATA (local access and transport area) - One of 161 USA geographical subdivisions used to define local as opposed to long distance telephone service.


Launch angle - The angle between the radiation vector and the axis of an optical fiber.


Lay - Pertaining to wire and cable, the axial distance required for one cabled conductor or conductor strand to complete one revolution about the axis around which it is cabled.


Lay direction - The twist in the cable as indicated by the top strands while looking along the axis of the cable away from the observer. Described as right hand or left hand.


Layer - Consecutive turns of a coil lying in a single plane.


L Band - The band of frequencies between 390 and 1,550 megahertz.


Lbf - Pound force.


LCL (longitudinal conversion loss) - A measurement of balance in a cable. Measured by applying a common-mode signal to the cable and measuring the differential at the near end.


LCTL (longitudinal conversion transfer loss) - Measured by applying a common-mode signal to a cable and measuring it at the far end of the cable. (Same as LCL but measures at far end.)


LDAP (Lightweight Directory Access Protocol) - An Internet protocol that e-mail programs use to look up contact information from a server.


Leaching and non-leaching - In a leaching wire the plasticizer will migrate when exposed to heat. A non-leaching wire will retain its plasticizer under extreme temperature conditions and remain flexible after baking.


Lead - A wire, with or without terminals, that connects two points in a circuit.


Lead cured - A cable that is cured or vulcanized in a metallic lead mold.


Lead-in - The conductor that provides the path for RF energy between the antenna and the radio and television receiver.


Leakage current - An undesirable flow of current through or over the surface of an insulating material.


Leakage distance - The shortest distance along an insulation surface between conductors.


Leap - Cisco proprietary wireless security protocol.


Leased line - A line intended for data communications that is leased from a telephone company. Leased lines are conditioned to a variety of specifications to keep impairments at a minimum. See also DIAL-UP.


LED (light-emitting diode) - Semiconductor device, much more reliable than an incandescent lamp, used for status display purposes in electronics equipment.


Length of lay - The axial length of one turn of the helix of a wire or member.


Level - A measure of the difference between a quantity or value and an established reference.


Level control - Main iris control. Used to set the auto iris circuit to a video level desired by the user. After setup, the circuit will adjust the iris to maintain this video level in changing lighting conditions. Turning the control toward high will open the iris, toward low will close the iris.


LF (low frequency) - A band of frequencies extending from 30 to 300 kHz in the radio spectrum, designated by the Federal Communications Commission.


Life cycle testing - A test to determine the length of time before failure in a controlled, usually accelerated environment.


Lightning ground cable - A specially stranded single conductor cable connecting lightning rods (air terminals) protecting buildings to adequate ground, such as grounding rods.


Light source - An object capable of emitting light. In fiber optics, the light source is normally a LED or a laser.


Light wave - The term used to describe the signal providing communication over optical fiber.


Limits of error - The maximum deviation (in degrees or percent) of the indicated temperature of a thermocouple from the actual temperature.


Limpness - The ability of a cable to lay flat or conform to a surface as with portable or microphone cables.


Line balance - The degree to which the conductors of a cable are alike in their electrical characteristics with respect to each other, to other conductors and to ground.


Line driver - A signal converter which conditions the digital signal transmitted by an RS-232 interface to ensure reliable transmission beyond the 50 ft. RS-232 limit and often up to several miles; it is a baseband transmission device.


Line drop - A voltage loss occurring between any two points in a power transmission line. Such loss, or drop, is due to the resistance, or leakage of the line.


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 fault - A fault such as an open circuit, short circuit or ground in an electrical line or circuit.


Line hit - An electrical surge, dip or transient that causes spurious signals in a circuit.


Line level - The level of a signal at a certain point on a transmission line. Usually expressed in decibels.


Line lock - To synchronize the field sync pulses, of an AC powered camera, to the frequency of the voltage input (line voltage).


Line loss - A total of the various energy losses occurring in a transmission line.


Line noise - Sustained high-frequency voltage excursions due to static electricity or RF interference from various sources.


Line turnaround - The reversal of transmission on a half-duplex circuit.


Line unbalance - Unequal loads on the phase lines of a multi-phase feeder.


Linevoltage - The value of the potential existing on a supply or power line.


Linearity - The property of a transmission medium or of an item of equipment that allows it to carry signals without introducing distortion.


Line voltage - The value of the potential existing on a supply or power line.


Link - Communications circuit or transmission path connecting two points.


Litz wire - Very fine, e.g. #44 AWG bare copper, each strand is enamel insulated. Used for low inductance coil windings.


LLC (logical link control) - Defined by IEEE 802.2, it is the upper half of the second layer of the OSI model. It interfaces with the MAC and the network layer.


LLDPE (linear low-density polyethylene) - Usually used as cable jacketing.


Load - A device that consumes or converts the power delivered by another device.


Load cell cable - Small multi-conductor shielded cables for connecting load cells with instruments in electronic strain gauges. It's also used for weighing and force measurement applications.


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 to a transmission line.


Loading - See LOADED LINE.


Lobe - In the multi-use communication loop, one of two separately driven sections of a loop. In the local area network, the section of cable that attaches a device to a wiring concentrator (access unit).


Loc-trac - Alpha's registered trademark for a zipper tubing closure track that does not require any sealants to keep it closed, even during extreme flexing.


Local area network (LAN) - A network that is located in a localized geographical area (e.g., an office, building, complex of buildings or campus) and whose communications technology provides a high-bandwidth, low-cost medium to which many nodes can be connected.


Local exchange, local central office - The exchange or central office in which the subscriber's lines terminate.


Local line, local loop - A channel connecting the subscriber's equipment to the line terminating equipment in the central office; usually a metallic circuit (either 2-wire or 4-wire).


LOMMF (laser-optimized multimode fiber) - Laser-optimized 50-micron multimode fiber, sometimes referred to as next-generation fiber, has enhanced bandwidth capable of supporting 10 Gigabit Ethernet at 850 nm using VCSEL technology. This is also a restricted mode launch so it avoids the pulse spreading due to DMD. Also called OM3.


Long-haul network - A network most frequently used to transfer data over distances from several thousand feet to several thousand miles. These networks can use the international telephone network to transmit messages over most or part of these distances.


Logging cable - Usually FEP/Tefzel self-supporting instrumentation cable. Generally dropped through borings in subsurface mining or well applications.


LCL (longitudinal conversion loss) - A measurement of balance in a cable. Measured by applying a common- mode signal to the cable and measuring the differential at the near end.


LCTL (longitudinal conversion transfer loss) - Measured by applying a common-mode signal to a cable and measuring it at the far end of the cable. (Same as LCL but measures at far end.)


Longitudinal shield - A tape shield, flat or corrugated, applied longitudinally with the axis of the cable.


Longitudinal shrinkage - A term generally applied to shrink products denoting the axial length lost through heating in order to obtain the recovered diameter.


Longitudinal wrap - Tape applied longitudinally with the axis of the core being covered.


Long wall machine - A mining machine used to undercut coal.


Loop - A closed circuit unidirectional signal path connecting input-output devices to the system.


Loop resistance - The total resistance of two conductors measured round trip from one end. Commonly used term in the thermocouple industry.


Loop test - A long line test where a good line is connected to a faulty line to form a loop in which measurements will locate the fault.


Looping - A term indicating that a high-impedance device has been permanently connected in a parallel to a video source.


Loopback, loopback test - Type of diagnostic test in which the transmitted signal is returned to the sending device, after passing through all of or a portion of ad at a communications link or network; this allows a technician (or built-in diagnostic circuit) to compare the returned signal with the transmitted signal. This comparison provides the basis for evaluating the operational status of the equipment and the transmission paths through which the signal traveled.


Loss – (1) The portion of energy applied to a system that is dissipated and performs no useful work. (2) Reduction in signal strength, expressed in decibels; also attenuation; opposite of GAIN.


Loss factor - The power factor times the dielectric constant.


Low bond insulation - An insulation that exhibits small bond strength to the conductors.


Low frequency - A band of frequencies extending from 30 to 300 kHz in the radio spectrum, designated by the Federal Communications Commission.


Low-loss dielectric - An insulating material that has a relatively low dielectric loss, such as polyethylene or Teflon. Dielectrics with tan δ below 0.01 (approximately) are considered low-loss materials.


Low-noise cable - A cable specially constructed to eliminate spurious electrical disturbances caused by capacitance changes or self-generated noise induced by either physical movement or adjacent circuitry.


Low tension - Low voltage, as applied to ignition cable.


Low voltage – (1) In the National Electrical Code, an electromotive force rated nominal 24 volts, nominal or less, supplied from a transformer, converter or battery. (2) In power system voltage ratings, a class of nominal system voltages 1,000 or less.


LPF - Low pass filter. A filter that greatly attenuates signals of higher than a specified frequency, but passes with minimal attenuation all signals lower in frequency.


LS (LOW SMOKE) - An optional rating for UL Listed cable types that also pass low smoke requirements contained in UL Standards. A cable that meets the requirements can be marked "LS."


LSZH - Abbreviation for low smoke, zero halogen. Sometimes also written LS0H (0=zero).


Lumen - A unit of measurement for light output.


Lux - A unit of measuring the intensity of light (1 FC = 10 lux).


LV - Low voltage.


LWAPP - Light Weight Access Point Protocol.

M

M-50 50/C high-speed modem cable - The 50/C cable assembly has the same function as the V.35 but allows for more circuit capability.


mA (milliampere)  - One-thousandth of an ampere.



MAC (media access control)  - The method by which network stations gain access to the network media and transmit information as part of the second layer of the OSI model.



Magnet wire  - Insulated wire used in the windings of motors, transformers and other electromagnetic devices.



Magnetic field  - The field created when current flows through a conductor; especially a coiled conductor.



Main cross-connect - A cross-connect for first level backbone cables, entrance cables and equipment cables.



Main distribution Ethernet  - See STANDARD ETHERNET.



Main ring path  - The party of the ring made up of access units and the cables connecting them.



Main trunk  - The major link(s) from the headend or hub to downstream branches.



MAN (metropolitan area network)  - A data network linking together terminals, memories and other resources at many sites within a city area. Each site may have its own local area network (LAN). Links between sites are usually on digital circuits rented from the local telephone company using a bit-rate appropriate to traffic requirements.



Manchester code  - A means of coding a single bit of data with two signaling pulses in the same time slot (0, 11, 1, 00), so there is a signal event for every bit of data, whether a 1 or a 0. This simplifies the clocking needed to interpret the bit stream at the receiving end.



Manual iris lens  - A lens with a manual adjustment to set the iris opening (f-stop) in a fixed position. Generally used for fixed lighting applications.



MAP (Manufacturing Automation Protocol)  - The OSI profile championed by General Motors Corporation to provide interconnectivity between plant hosts, area managers and cell controllers over a broadband token-passing bus network.



MAP (multiservice access platform)  - Like a DSLAM they can provide service over copper wire using DSL technology but MAPs carry additional capabilities by also supporting FTTH and other types on interfaces out of the same platform. It has Quos capabilities also.



MAP/TOP (Manufacturing Automation Protocol/Technical Office Protocol)  - MAP originally developed by General Motors, defines OSI protocols and application utilities for use in the manufacturing environment. TOP, originally developed by Boeing, performs the same function for the office.



Mark  - 1. In single-current telegraph communications, represents the closed, current-flowing condition. 2. In data communications, represents a binary 1; the steady state, no-traffic state for asynchronous transmission. 3. The idle condition.



Marker tape  - A tape laid parallel to the conductors under the sheath in a cable, imprinted with the manufacturer's name and the specification to which the cable is made.



Marker thread  - A colored thread laid parallel and adjacent to the strand in an insulated conductor that identifies the manufacturer and sometimes the specification to which the wire is made.



Mastic - A meltable coating used on the inside of some shrink products that when heated flows to help create a waterproof seal.



MAT  - Metropolitan area trunks.



Matrix switcher  - A switcher able to route any of its (camera) inputs to any of its (monitor) outputs, they often include telemetry control.



MATV (master antenna television system)  - A small, less expensive cable system usually restricted to one or two buildings such as hospitals, apartments, libraries, hotels, office buildings, etc.



MAU (media access unit)  - Circuitry used in LANs to enable data terminal equipment to access the transmission medium.



Maximum cable diameter  - The largest cable diameter that a high-voltage cable termination is designed to accommodate.



Maximum design voltage  - The maximum voltage at which a high-voltage cable termination is designed to operate continuously under normal conditions.



Mbps (megabits per second)  - A unit of data transmission speed.



MC  - Main cross connect.



MDF  - Main distribution frame.



MDPE (medium-density polyethylene) - Usually used as cable jacketing.



MDU (multiple dwelling units)  - Apartment buildings and condominiums.



Mechanical focus (back-focus) - The mechanical aligning of the imaging device with the focal point of the lens; it is most important on zoom lenses to be sure the image stays in focus throughout the zoom range.



Mechanical water absorption  - A check of how much water will be absorbed by material in warm water for seven days (mg/sq. in. surface).



Medium frequency  - The band of frequencies between 300 and 3,000 kilohertz.



Medium voltage  - A class of nominal power system voltage ratings between 2.4 and 46 kV.



Medium-and hard-drawn wire - As applied to copper wire, having tensile strength less than the minimum for hard drawn wire, but greater than the maximum for soft wire.



Mega  - Prefix meaning million.



Megahertz (MHz)  - One million cycles per second.



Megger  - A special ohmmeter for measuring very high resistance. Primarily used for checking the insulation resistance of cables; however, it is also useful for leakage tests.



Melinex  - ICI trademark for polyester. See MYLAR.



Melt index  - The extrusion rate of a material through a specified orifice under specified conditions.



Member  - A group of wires stranded together that is in turn stranded into a multiple member conductor.



Messenger wire  - A metallic supporting member either solid or stranded which may also perform the function of a conductor.



MFD  - Microfarad (one-millionth of a farad). Obsolete abbreviation.



MFT  - Abbreviation for 1,000 feet. M is one thousand in the Roman numeral system.



MG  - Glass reinforced mica tape insulated cable with an overall sheath of woven glass yarn impregnated with a flame, heat and moisture resistant finish. 450°C, 600 V appliance wire.



MHO  - The unit of conductivity. The reciprocal of an ohm.



MHz (megahertz)  - One million cycles per second.



MI  - A UL cable type. One or more conductors insulated with highly compressed refractory minerals and enclosed in a liquid-tight and gas-tight metallic tube sheathing.



MIB (management information base)  - A set of descriptions of manageable features, used with SNMP devices. MIBS are unique per manufacturer and assigned by the IANA (Internet Assigned Numbers Authority).



MIC - 1. Media interface connector. A FDDI fiber connector or an IBM Type 1 connector. 2. Multifiber indoor cable. A corning term.



MICA  - A transparent silicate that separates into layers and has high insulation resistance, high dielectric strength and high heat resistance.



MICE (mechanical, ingress, climatic and electromagnetic)  - A TIA rating system for the survivability of cabling components in varying degrees of environmental challenges.



Micro  - Prefix meaning one-millionth.



Micro-bending loss - A signal loss due to small geometrical irregularities along the core cladding interface of optical fibers.



Microfarad  - One-millionth of a farad (µf, µfd, mf, and mfd are common abbreviations).



Micro-microfarad - One millionth of a microfarad (µµf, µµfd, mmf, mmfd are common abbreviations). Also, a picofarad (pf or pfd).



Micron (µm)  - One-millionth of a meter.



Microphone cable  - A very flexible, usually shielded cable used for audio signals.



Microphonics  - Noise caused by mechanical movement of a system component. In a single conductor microphone cable, for example, micro phonics can be caused by the shield rubbing against the dielectric as the cable is flexed.



Microprocessor  - A computer-on-a-chip.



Microwave  - A short (usually less than 30 cm wavelength) electrical wave.



Mid-split - A broadband cable system in which the cable bandwidth is divided between transmits and receives frequencies. The bandwidth used to send toward the headend (reverse direction) is approximately 5 MHz to 100 MHz and the bandwidth used to send away from the head-end (forward direction) is approximately 160 MHz to 300 MHz.



Mil  - A unit of length equal to one thousandth of an inch.



MIL-DTL-16878 - A military specification covering various wires intended for internal wiring of electric and electronic equipment. Formerly MIL-C-16878.



MIL-DTL-17 - A military specification covering many coaxial cables. Formerly MIL-C-17.



Milli  - Prefix meaning one-thousandth.



MIL-SPEC - Military specification.



MIL-W-22759 - A military specification for fluorocarbon insulated copper and copper alloy wire. Replaced by SAE AS22759.



Minimum cable diameter - The smallest cable diameter that a high-voltage cable termination is designed to accommodate.



Minimum object distance (MOD)  - The closest distance a given lens will be able to focus upon an object. This is measured from the vertex (front) of the lens to the object. Wide angle lenses generally have a smaller MOD than large focal length lenses.



MIPS (millions of instructions per second)  - One measure of processing power.



Mj (modular jack)  - A jack used for connecting voice cables to a faceplate.



MMDS (multichannel multipoint distribution service)  - Fixed wireless/wireless broadband.



MMJ (modified modular jack)  - A jack used for connecting data cables to a faceplate.



Modem eliminator, modem emulator  - A device used to connect a local terminal and a computer port in lieu of the pair of modems that they would expect to connect to; allows DTE to-DTE data and control signal connections otherwise not easily achieved by standard cables or connectors. Modified cables (crossover cables) or connectors (adapters) can also perform this function.



Modem  - A contraction of modulate and demodulate; a conversion device installed in pairs at each end of an analog communications line. The modem at the transmitting end modulates digital signals received locally from a computer or terminal; the modem at the receiving end demodulates the incoming analog signal, converts it back to its original (i.e., digital) format and passes it to the destination device.



Modular plug  - A series of connecting devices adopted by the FCC as the standard interface for telephone and data equipment to the public network. The most common is the RJ11, used to connect a single line phone and RJ45 for data.



Modular  - Equipment is said to be modular when it is made of plug-in-units that can be added together to make the system larger and improve its capabilities or expand its size. There are very few phone systems that are truly modular.



Modulate  - To change or vary some parameter such as varying the amplitude of a signal for the amplitude modulation or the frequency of a signal for frequency modulation. The circuit that modulates the signal is called a modulator.



Modulation  - 1. The act of modifying the amplitude, phase or frequency of a carrier to allow the transmission of information. 2. The process by which a carrier is varied to represent an information carrying signal. See AM, FM and PHASE MODULATION.



Module  - 1. In hardware, short for card module. 2. In software, a program unit or subdivision that performs one or more functions.



Modulus of elasticity  - The ratio of stress (force) to strain (deformation) in a material that is elastically deformed.



MOF  - Metal-clad optical fiber.



Moisture absorption  - The amount of moisture, in percentage, that a material will absorb under specified conditions.



Moisture resistance  - The ability of a material to resist absorbing moisture from the air or when immersed in water.



Molded plug  - A connector molded on either end of a cord or cable.



Mono filament  - A single-strand filament as opposed to a braided or twisted filament.



Monochrome signal  - In monochrome television, a signal for controlling the brightness values in the picture. In color television; the signal that controls the brightness of the picture, whether the picture is displayed in color or in monochrome.



Monochrome  - Having only one color. In television it is black and white.



Monomer  - The basic chemical unit used in building a polymer.



Motor lead wire  - Wire that connects to the fragile magnet wire found in coils, transformers and stator or field windings.



MPEG  - Motion Picture Experts Group.



MPF  - Mine power feeder cables. Usually rated 5, 8, or 15 kV.



MPLS (Multiprotocol Label Switching)  - A connection-oriented switching, not routing, technology, used as a mechanism for assuring QOS on IP networks.



MSDS  - Material safety data sheets.



MSHA  - Mine Safety and Health Administration. The Federal enforcement agency for employee safety in mines and mills. Formerly known as MESA, Bureau of mines. MSHA regulations appear in CFR (Code of Federal Regulations) Title 30, Chapter 1.



MTU  - Multiple tenant units (office buildings).



MTW  - Machine tool wire, a UL cable type. Thermoplastic insulated, 90°C to 105°C, 600 V. UL 1063 is the governing standard.



Multicast  - The ability to broadcast messages to one node or a select group of nodes.



Multi-drop - See MULTIPOINT CIRCUIT.



Multimode  - Optical fiber that allows more than one mode of light to propagate. A step-index fiber has a core of uniform refractive index while in a graded-index fiber the refractive index of the core smoothly varies with the radius.



Multiple-conductor cable - A combination of two or more conductors cabled together and insulated from one another and from sheath or armor where used.



Multiple-conductor concentric cable - An insulated central conductor with one or more tubular stranded conductors laid over it concentrically and insulated from one another.



Multiplex  - The use of a common physical channel in order to make two or more logical channels, either by splitting of the frequency band (frequency-division multiplex) or by utilizing this common channel at different points in time (time-division multiplex).



Multiplexing/multiplexers  - 1. Equipment that permits simultaneous transmission of multiple signals over one physical circuit. 2. The division of a composite signal among several channels; concentrators, FDMs and TDMs are different kinds of multiplexers.



Multipoint circuit  - A single line connecting three or more stations.



Multipoint circuit  - A single line connecting three or more stations.



Multiport repeater  - A repeater that is used to connect more than two cable segments.



Multiport transceiver  - Multiple transceiver connection packaged in a common rack. Provides one transceiver attachment to the trunk cable and the ability to serve up to eight stations.



Multi-segment LAN - A LAN that is composed of more than one coaxial cable segment.



Multi-station access unit - In the IBM Token-Ring Network, a wiring concentrator that can connect up to eight lobes to a ring network, the 8228. Also the four-lobe unit from General Instrument that uses Type 3 Media Cable.



Murray loop test  - A method used to localize cable faults.



Mutual capacitance  - Capacitance between two conductors in a cable.



MUX (multiplex)  - To transmit two or more signals over a single channel.



Muxer  - Multiplexer. Electronic equipment which allows two or more signals to pass over one telephone line.



MV (medium voltage)  - Cables usually rated 5 to 35 kV.



mV (millivolt)  - One-thousandth of a volt.



mW (milliwatt)  - One-thousandth of a watt.



Mylar  - DuPont trademark of polyethylene terephtalate (polyester) film. See MELINEX.

N

N connector - A threaded connector used to join to coax cable; N is named after Paul Neill.


N/d (neutral density) filter - A filter that attenuates light equally over the whole visible spectrum.


N-series connector - A coaxial connector (RG-8/U) used in standard Ethernet networks.


NAM - Network access method.


NAS (network attached storage) - A data storage device that is attached directly to the main data network. (Lower cost than a SAN but shares bandwidth with the data network.)


NAT (network address translation/translator) - A device, or just software on a computer, that can separate a LAN network from the Internet. Routers are often NAT routers. It translates an internal IP address to an outside public IP address.
NBR/PVC - A blend of acrylonitrile-butadiene rubber; a material with good oil and chemical resistance and polyvinyl chloride (PVC). Used for jacketing.


NBR - Butadiene-acrylonitrile copolymer rubber, a material with good oil and chemical resistance.


NBR/PVC - A blend of acrylonitrile-butadiene rubber and polyvinyl chloride (PVC). Used for jacketing.


NBS (National Bureau of Standards) - A U.S. government agency that produces Federal Information Processing Standards (FIPS) for all U.S. government agencies and network users. Now called NIST (National Institute of Standards and Technology).


NEBS (network equipment building systems) - Standards defined test levels created by Telecordia Technologies (formerly Bellcore) in 1985 for the telecommunications industry. NEBS testing is required in the U.S. for equipment operated in the carrier networks of Regional Bell Operating Companies (RBOCs) and competitive local exchange carriers (CLECs).


NEC - National Electrical Code.


Negative sequence impedance - The electrical impedance of a three-phase power cable with the phase rotation reversed as compared to normal operation. Has the same numerical value as the positive sequence impedance. "Negative sequence" refers to the phase relationship of the currents in the conductors.


NEMA - National Electrical Manufacturers Association.


Neoprene - A synthetic rubber with good resistance to oil, chemical and flame. Also called polychloroprene.


Netview - IBM's network management product for its SNA networks. It can collect information from non-SMA environments via NetView/PC.


Netware - A popular proprietary network operating system from Novell, Inc.


Network - A series of nodes connected by communications channels.


Network channel terminating equipment - Equipment used at the customer premises to provide facility termination and signaling compatibility. Also called channel service unit (CSU).


Network facilities - In a packet-switched network, standard facilities are divided into essential facilities (found on all networks) and additional facilities (selected for a given network but which may or may not be selected for other networks).


Networking - The connection of one ISN system to other compatible local area networks or PBXs.


Network interface controller - A communications device that allows interconnection of information processing devices to a network.


Network management - Administrative services performed in managing a network, such as network topology and software configuration, downloading of software, monitoring network performance, maintaining network operations and diagnosing and troubleshooting problems.


Network protection device - A device which provides isolation between PBX circuits and CO trunks or tie lines.


Network topology - The physical and logical relationship of nodes in a network. Networks are typically of a star, ring, tree or bus topology or some hybrid combination thereof.


Newton - The derived SI unit for force; the force that will give one kilogram mass an acceleration of one meter per second: 1N=1 • (kg •m) / s-2.


Next - Near-end crosstalk. A measure of the unwanted signal coupling from a transmitter at the near-end into a neighboring (non-energized) pair measured at the near-end.


NFPA - National Fire Protection Association.


NIC (network interface card) - Also called controller card, PC expansion card, controller board, network interface controller, adapter card, adapter board, network adapter module or network interface module. Its function is to allow the workstation to be physically and electronically connected to some specific network at the physical and data link layer.


Nickel clad copper wire - A wire with a layer of nickel on a copper core where the area of the nickel is approximately 30 percent of the conductor area.


NIST - National Institute of Standards and Technology. Formerly the National Bureau of Standards.


NIU - Network interface unit.


Nm-b - A UL cable type rated 600 volts and intended for use per Article 334 of the NEC. Nonmetallic sheathed cable. For dry use, 90°C conductor rating.


Nmc-b - A UL cable type rated 600 volts and intended for use per Article 334 of the NEC. Nonmetallic sheathed cable. Wet or dry use, 90°C conductor rating.


Node - A station.


Noise - In a cable or circuit, any extraneous sounds or signal which ends to interfere with the sound or signal normally present in or passing through the system.


Nomex - DuPont trademark for a temperature-resistant, flame-retardant nylon.


Nominal - Name or identifying value of a measurable property by which a conductor or component or property of a conductor is identified and to which tolerances are applied.


Nominal voltage (national electrical code) - A nominal value assigned to a circuit or system for the purpose of conveniently designating its voltage class (as 120/240, 480Y/277, 600 volts, etc.). The actual voltage at which a circuit operates can vary from the nominal within a range that permits satisfactory operation of equipment.


Nomograph - A chart or diagram with which equations can be solved graphically by placing a straight edge on two known values and reading the answer where the straight edge crosses the scale of the unknown value.


Noncontaminating - A type of PVC jacket material whose plasticizer will not migrate into the dielectric of a coaxial cable and thus avoid contaminating and destroying the dielectric.


Noncontaminating pvc - A polyvinyl chloride formulation that does not produce electrical contamination through plasticizer migration.


Nonflammable - The property of a material that is not capable of being easily ignited.


Nonmigrating pvc - Polyvinyl chloride compound formulated to inhibit plasticizer migration.


NOS (network operating system) - A generic term that applies to local area network operating system software.


NRZ (non-return to zero) - The common encoding of a binary stream into two voltage levels.


NRZI (non-return to zero inverted) - In SDLCO, a binary encoding technique in which a change in state represents a binary 0 and no change in state represents a binary 1.


NT - Network termination.


NTP (network time protocol) - A protocol designed to synchronize the clocks of computers over a network.


NTSC (National Television System Committee) - The television standard for North America and parts of South America having 525 lines/60 Hz (60 Hz refresh), two fields per frame and 30 frames per second (60 fields per second).


Null modem - Same as modem eliminator.


Null modem cable assemblies - The null modem cable assembly utilized the RS-232 cable system and replaces short distance modems.


Numerical aperture - The acceptance angle of an optical fiber which determines the angle at which light can enter the fiber; expressed as a number that is equivalent to the sine of the angle.


NVP (nominal velocity of propagation) - This is a measure of how fast a signal travels along a line.


NVR (network video recorder) - A storage device on a network for storing IP video.


Nylon - An abrasion-resistant thermoplastic with good chemical resistance.


NZDSF - Non-zero dispersion shifted fiber.