Term Definition
5-Mil Copper Solid Copper Shield. Provides added electrical protection.
802.14 IEEE's Cable TV MAC and PHY Protocol Working Group.
A Ampere
ABR Available Bit Rate.
Abrasion Resistance Ability of a wire, cable or material to resist surface wear.
Abrasion Stripper More accurately described as "buffing stripper", which is a motorized device for removing flat cable insulation by means of one or two buffing wheels that melt the insulation and brush it away from the conductors.
AC Alternating current. Electric current that alternates or reverses polarity in a cyclical manner (e.g. 60 Hertz AC power)
Accelerated Aging A test that simulates long time environmental conditions in a relatively short time.
Access Method The way in which a node is permitted to send data over the media. With Ethernet, the node listens to the line to determine if it is available (heartbeat) before transmitting.
ACR Attenuation Crosstalk Ratio. The difference between attenuation and crosstalk, measured in dB, at a given frequency. Important characteristic in networking transmission to assure that signal sent down a twisted pair is stronger at the receiving end of the cable than are any interference signals imposed on that same pair by crosstalk from other pairs.
Adapter A device used to join two like or different fiber optic connectors together. Adapters made to join different connectors are called hybridadapters.
Address A number uniquely identifying each node in a network (MAC address).
ADSL Asymmetric Digital Subscriber Line
AES/EBU Informal name of a digital audio standard established jointly by the AES (Audio Engineering Society) and EBU (European Broadcast Union) organizations.
AF Audio frequency.
Air Core Cables that are not gel filled.
Air-Gap Dielectric A coaxial design in which a monofilament of plastic holds the center conductor in place in a hollow plastic tube allowing the remainder of the dielectric to be air. Typical velocities of up to 84% can be achieved in this design.
Alloy A combination of two or more different polymers/metals. Usually combined to make use of different properties of each polymer/ metal.
Alpeth Coated Aluminum Polyethylene.  Basic sheath.
Alternating Current (AC) Electric current that alternates or reverses polarity in a cyclical manner (e.g. 60 Hertz AC power)
AM Amplitude modulation.
Ambient Conditions that exist in the environment of the cable. Conditions existing at a test or operating location prior to energizing equipment (e.g.: ambient temperature).
American Wire Gauge (AWG) A standard for expressing wire diameter. As the AWG number gets smaller, the wire diameter gets larger.
Ampacity Current handling capability expressed in amperes. The maximum current a conductor can carry without being heated beyond a safe limit.
Ampere A standard unit of current. Defined as the amount of current that flows when one volt of electromotive force (EMF) is applied across one ohm of resistance. One ampere of current is produced by one coulomb of charge passing a point in one second.
Amplitude The magnitude of a current or voltage. It can be the maximum, minimum, average, or RMS value of an alternating current (AC) signal. These four magnitudes are the same for a direct current (DC) signal.
Analog Representation of data by continuously variable quantities as opposed to a finite number of discrete quantities in digital.
Analog Signal An electrical signal which varies continuously, not having discrete values. Analog signals are copies or representations of other waves in nature. An analog audio signal, for instance, is a representation of the pressure waves which make up audible sound.
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. Annealing generally lowers the tensile strength of the material, while improving its flex life and flexibility.
ANSI American National Standards Institute.
APC This is a specialized polishing procedure (Angle-polish Physical Contact). There is an 8 degree angle created in the polish. It is typically used on simplex Single mode cable with SC connectors. It is used with high-end lasers or receivers where there are concerns for back reflection.
Application Layer The seventh layer in the OSI model, which is ultimately responsible for managing communication between application processes.
Aramid Yarn Strength elements that provide tensile strength, support, and additional protection for fiber bundles. Kevlar is a brand name of aramid fiber.
Armor Additional protective element beneath a cable outer jack to provide higher level protection for the inner cable components. Usually made of plastic coated steel, sometimes corrugated for flexibility.
ASCII (American Standard Code for Information Interchange) - A widely used 7-bit code-set established by ANSI to achieve compatibility between products manufactured by different companies.
ASP Aluminum Steel Polyethylene.  Provides mechanical and electrical protection.
ASTM The American Society for Testing and Materials, a standards organization which suggests test methods, definitions and practices.
Asynchronous Transfer Mode The SONET standard for a packet switching technique which uses packets of a fixed length.
ATM Asynchronous Transfer Mode.
Attenuation The decrease in magnitude of a signal as it travels through any transmitting medium, such as a cable or circuitry. Attenuation is usually expressed logarithmically as the ratio of the original and decreased signal amplitudes. It is usually expressed in decibels (dB).
Audio A term used to describe sounds within the range of human hearing (20 Hz to 20 kHz). Also used to describe devices which are designed to operate within this range.
Audio Frequency Frequencies within the range of human hearing (approximately 20 Hz to 20 kHz).
AUI (Attachment Unit Interface) - A cable interface located between a MAU and a DTE, referred to as a DB15.
AWG American Wire Gage. A wire diameter specification. The smaller the AWG number, the larger the wire diameter.
AWM Appliance Wiring Material. A UL designation for a type of wire.
Backbone The cable used to connect all systems of a multi-level distributed system to an intermediate system.
Backbone Cabling The portion of premises cabling that provides connections between primary data and telecommunications equipment and infrastructure access points.
Backshell Housing on a connector that covers the area where the cable conductors connect to the connector contacts. It can be a metal housing providing continuity of the shield through IDC connectors.
Balanced Line A cable having two identical conductors which carry voltages opposite in polarity, but equal in magnitude with respect to ground, suitable for differential signal transmission.
Balun Balanced to unbalanced (Bal-un) transformer used to connect an unbalanced transmission line (i.e. coaxial cable) to a balanced system or cable, or vice versa. It can also provide impedance transformation, as 300 ohm balanced to 75 ohm unbalanced.
Bandwidth The difference between the upper and lower limits of a given band of frequencies. It is expressed in hertz.  The range of frequencies that a transmitted communications signal occupies or that a receiving system can accept.  For example, it takes more bandwidth to download a photograph in a second than to download a page of text.  Virtual reality and three-dimensional audio/visual presentations require even more.
Baseband A transmission technique that allows only one signal at one time to travel on a cable.
Baud Rate of digital transmission equal to the reciprocal of the time of one output signaling element.
Bel A unit that represents the logarithm of the ratio of two levels. One bel equals the base 10 logarithm of the ratio of two power levels. It is also equal to the base 10 logarithm of square of the ratio of two voltage or current levels, provided the impedances are the same at the two levels. See dB.
Belden A leading manufacturer of the specialty wire, cable and fiber products needed for new applications in data, audio, video and voice signal transmission, among other things.
Beldfoil Belden trademark for highly effective electrostatic shield of reinforced metallic foil.
Beldsol Solderable Belden magnet wire combining insulating films of polyurethane for excellent dielectric characteristics and nylon for mechanical protection.
Belflex® A premium hybrid matte-finish jacket material that exhibits superior flexibility at low temperatures along with excellent abrasion resistance compared to standard PVC jacketing materials.
Bend Loss A form of increased attenuation caused by (a) having an optical fiber curved around a restrictive radius of curvature or (b) microbends caused by minute distortions in the fiber imposed by externally induced perturbations.
Bend Radius Radius of curvature that a flat, round, fiber optic or metallic cable can bend without any adverse effects.
Binder A tape or thread used for holding assembled cable components in place.
Bit One binary digit.
Bit Error Rate The number of errors occurring in a system per unit of time (e.g. bits per second)
Bits Per Second The number of binary bits that can be transmitted per second (bps) - i.e. Mbps (Mega = million), Gbps (Giga = billion).
BNC Abbreviation for "Bayonet Neil Concelman". A coaxial cable connector used extensively in video and R. F. applications and named for its inventors.
Bonded 1. Adhesive application of a metallic shielding tape to the dielectric of a coaxial cable to improved electrical performance and ease of connector installation. Also refers to adhesive application of a metallic shielding taper to the jacket of a cable. 2. Steel is bonded to polyethylene with a copolymer adhesive All STALPETH and some ASP cables are bonded.  Provides extra strength to jacket, primarily used in underground applications.
Bonded ASP Aluminum Steel Polyethylene where the steel is bonded to polyethylene for strength.  Filled cables for use in ducts.
Bonding The method used to produce good electrical contact between metallic parts of any device. Used extensively in automobiles and aircraft to prevent static buildup. Also refers to the connectors and straps used to bond equipment.
Booster An amplifier inserted into a cable to increase the signal amplitude in order to compensate for signal loss due to attenuation. This extends the transmission range of the cable. Transformers may be employed to boost ac voltages. The term booster is also applied to amplifiers used in television receiving antenna systems.
BPS Bits per second (see).
BPSK Binary Phase Sift Keying. A type of digital transmission where two phases of the signal are possible to represent binary one and zero.
Braid A group of textile or metallic filaments interwoven to form a tubular flexible structure which may be applied over one or more wires, or flattened to form a strap.
Braid Angle The angle between a strand of wire in a braid shield and the longitudinal axis (i.e.axis along the length of the center) of the cable it is wound around.
Breakdown Voltage The voltage at which the insulation between two conductors will fail and allow electricity to conduct or 'arc'.
Breakout The point at which a conductor or conductors are separated from a multi-conductor cable to complete circuits at various points along the main cable.
Breakout Cable This multiple fiber cable is used in more heavy duty applications. Each fiber in the cable (12 or 24) is individually padded and wrapped. It handles pressure, strain, impact, and repetitive motion very well.
BRI Basic Rate Interface ISDN.
Bridge A LAN interconnection device used to link two or more local or remote LANS. Bridges are used extensively in LAN systems to extend their physical dimensions or modify their performance. These have mostly been replaced by Switches and Routers.
Bridge MIB A specification that defines an experimental portion of the Management Information Base for use with network managing protocols in TCP/IP based internets. In particular, it defines objects for managing bridges based on the IEEE 802.3.
Broadband The technique used to multiplex multiple networks on a single cable without interfering with each other.  Technologies that allow you to transmit or receive higher volumes of data at higher speeds.
Brouter A network device that can perform the functions of both a bridge and a router.
Buffer A protective coating over an optical fiber.
Buffering (1) A protective material extruded directly on the fiber coating to protect it from the environment (tight-buffered); (2) extruding a tube around the coated fiber to allow isolation of the fiber from stresses in the cable (buffer tubes).
Buffing Stripper A motorized device for removing flat cable insulation by means of one or two buffing wheels that melt the insulation and brush it away from the conductors. Also called Abrasion Stripper.
Bunch Strand Conductors twisted together with the same lay and direction without regard to geometric pattern.
Buried Cables that are required to go underground.
Bus topology A structure used in LANs whereby connection between devices is accomplished by connecting all devices to a single transmission medium such as fiber or wire.
Bus-bar Wire Uninsulated tinned copper wire used as a common lead.
Butyl Rubber A synthetic rubber with good electrical insulating properties.
Byte A group of eight adjacent binary digits (8 bits).
C Capacitance (electrical). Celsius (temperature).
Cable A group of individually insulated conductors or subcomponents twisted helically.
Cable Assembly Optical fiber cable that has connectors installed on one or both ends. General use of these cable assemblies includes the interconnection of the optical fiber cable systems and optoelectronic equipment. If connectors are attached to only one end of a cable, it is commonly known as a pigtail. If connectors are attached to both ends it is commonly called a jumper or patch cord.
Cable Bend Radius Cable bend radius during installation infers that the cable is experiencing a tensile load (pulling force). Free bend infers a smaller allowable bend radius since it is at a condition of no load (after installation).
Cable Modem A device that enables you to hook up your PC to a local cable TV line and receive data at much faster rates than telephone modems and ISDN lines.  A strong competitor to DSL telephone service.
Cabling The grouping or twisting together of two or more insulated conductors or subcomponents to form a cable.
CACSP Coated Aluminum, Coated Steel, Polyethylene.  Provides additional strength and protection.
Canadian Electrical Code (CEC) Canadian version of the US National Electrical Code (NEC).
CAP Carrierless Amplitude Phase Modulation.
Capacitance The ability of a dielectric material between conductors to store energy when a difference of potential exists between the conductors. The unit of measurement is the farad. Cable capacitance is usually measured in picofarads (pF).
Capacitive Crosstalk Cable crosstalk or interference resulting from the coupling of the electrostatic field of one conductor upon one or more others.
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/(2*pi*f*C) where pi is approximately 3.1416, 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 surfaces, type of dielectric, and spacing between the conducting surfaces.
Carrier Strip Also referred to as substrate. A film that is on one side of a laminated flat cable.
CASPIC Coated Aluminum, Coated Steel.
Category Rating of a local area network (LAN) cable established by TIA/EIA to indicate the level of electrical performance.
Category Cables Belden manufactures Category 3 to 7 cables, all high performance twisted pair data cables.  The higher the category number, the greater the bandwidth.  Category 7 is currently the highest performance telecommunication wire available.  Ours is certified to applicable UL standards.
CATV Abbreviation for Community Antenna Television.  Cable TV.
CB Citizens band.
CBR Constant Bit Rate.
CCTV Closed-circuit television.
Cellular Polyethylene Expanded or "foam" polyethylene, consists of individual closed cells of inert gas suspended in a polyethylene medium. The result is a desirable reduction of the dielectric constant compared to solid polyethylene, which decreases attenuation and increases the velocity of propagation.
Center-to-Center Distance Pitch. Nominal distance from center-to-center of adjacent conductors within a cable. When conductors are flat, pitch is usually measured from the reference edge of a conductor to the reference edge of the adjacent conductor.
Channel The horizontal cable including the workstation outlet and patch panel in the telecommunications closet plus a maximum combined length of up to ten meters of patch cable at each end (maximum length of 100 meters).
Characteristic Impedance In a transmission cable of infinite length, the ratio of the applied voltage to the resultant current at the point the voltage is applied. Or the impedance which makes a transmission cable seem infinitely long, when connected across the cable's output terminals.
Chrominance Signal The portion of a video signal that contains the color information.
Circuit A system of conducting media designed to pass an electric current.
Circular Mil Area of a wire that is one-thousandth of an inch (.001 inch, one mil) in diameter. This area is pi/4 of a square mil. The circular mil area (CMA, cmil) equals the diameter in mils squared. By knowing the CMA of various conductors, they can be used to determine what conductivity and gage size various combinations will produce.
Cladding A low refractive index material that surrounds the core of an optical fiber causing the transmitted light to travel down the core and protects against surface contaminant scattering or a layer of metal applied over another. Cladding is often chosen to improve conductivity or to resist corrosion.
Client In the ISO/OSI specifications, the client is referred to as the service requester.
CMIP (Common Management Information Services) - The network management protocol defined by OSI specifications. Used to convey CMIS defined operations over an OSI network.
CO Central Office.
Coating A material put on a fiber during the drawing process to protect it from the environment and handling.
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 insulating jacket. Used by cable TV companies to distribute signals to homes and businesses. Also used by telephone companies in some applications and by cellular telephone, radio, and television installations.
Coil Effect The inductive effect exhibited by a spiral-wrapped shield, especially above audio frequencies.
Collision A condition in which two packets are being transmitted over a medium at the same time, resulting in destruction of the data. Ethernet quickly recovers and retransmissions of the data are made.
Color Code A system of different colors or stripes used to identify components of cables such as individual conductors or groups of conductors.
COLS Commercial Online Service.
Component Video The unencoded output of a camera, video tape recorder, etc., whereby each red, green, and blue video signal is transmitted down a separate cable (usually coax) to improve picture quality. Can also refer to a video system where the luminance and chrominance video components are kept separate.
Composite Cable Cable having conductors with two or more AWG sizes or more than one cable type.
Composite Video The encoded output of a camera, video tape recorder, etc., whereby the red, green, and blue video signals are combined with the synchronizing, blanking, and color burst signals and are transmitted simultaneously down one cable.
Concentrator Any communications device that allows a shared transmission medium to accommodate more date sources than there are channels currently available with the transmission medium (example, a Hub).
Concentric Stranding A group of uninsulated wires twisted together and containing a center core with subsequent layers spirally wrapped around the core with alternating lay directions to form a single conductor.
Conductivity The ability of a material to allow electrons to flow, measured by the current per unit of voltage applied. It is the reciprocal of resistivity and is measured in siemens (S) or mhos.
Conductor A substance, usually metal, used to transfer electrical energy from point to point.
Conduit A tube of metal or plastic through which wire or cable can be run. Used to protect the wire or cable and, in the case of metal conduit, to contain the fire of a burning wire or cable.
Connector A device designed to allow electrical flow from one wire or cable to a device on another cable. A connector will allow interruption of the circuit or the transfer to another circuit without any cutting of wire or cable or other preparation.
Copperweld Trademark of Copperweld Steel Co. for copper-clad steel conductor.
Cord A very flexible insulated cable.
Core The light conducting central portion of an optical fiber with a refractive index higher than that of the cladding. The center of a cable construction. Most often applies to a coaxial cable, where the core is the center conductor and the dielectric material applied to it.
Corona The ionization of gasses about a conductor that results when the potential gradient reaches a certain value.
Coupling The transfer of energy (without direct electrical contact) between two or more cables or components of a circuit.
Coverage How well a metal shield covers the underlying surface. Measured in percent.
CPE Chlorinated polyethylene can be used as either a thermoplastic or thermoset. It is a tough chemical and oil-resistant material and makes an excellent jacket for industrial control cable. As a thermoset, it can be used as an oil resistant cord jacket. Other outstanding properties include low water absorption and superior crush resistance, which are important attributes in industrial control applications.
CPS Abbreviation for cycles per second. This term has been replace by hertz is common usage.
CPU Central Processing Unit.
Crosstalk A type of interference caused by signals from one pair or cable being coupled into adjacent pairs or cables. Can occur with audio, data, or RF signals.
CRT Cathode Ray Tube.
CSA Abbreviation for Canadian Standards Association, the Canadian version of the Underwriters Laboratories.
CSMA (Carrier Sense Multiple Access) - A medium access control technique for multiple access transmission media. A station wishing to transmit first senses the medium (heartbeat) and transmits only if the medium is idle.
CSMA/D Carrier Sense Multiple Access/Collision Detection.
CSR Customer Service Representative.
CUPIC Copper.
Current Carrying Capacity The maximum current a conductor can carry without being heated beyond a safe limit. Ampacity.
Current Loop A two wire transmit/receive interface.
Current, Alternating (ac) Electric current that alternates or reverses polarity in a cyclical manner (e.g. 60 Hertz AC power).
Current, Direct (dc) Electrical current whose electrons flow in one direction only and is generally constant.
Cut-through Resistance A test to determine the ability of a material to withstand the application of blades or sharp edges without being cut.
D1 A component digital video recording format that conforms to the CCIR-601 standard. Records on 19 mm magnetic tape. (Often used incorrectly to indicate component digital video).
D2 A composite digital video recording format. Records on 19 mm magnetic tape.
D3 A composite digital video recording format. Records on 1/2 inch (12.7 mm) magnetic tape.
Daisy Chain A cable assembly with three or more termination areas.
Datalene Belden trademark for foam polyolefin.
DAVIC Digital Audio Video Council.
dB Decibel.
DBS Direct Broadcast Satellite.
DC Direct current.
DC Resistance See resistance.
Decibel (dB) A decibel is one-tenth of a bel and 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. Decibels are also used to express acoustic power, such as the apparent level of a sound. The decibel can express an actual level only when comparing with some definite reference level that is assumed to be zero dB.
Delay Line A transmission line or equivalent device designed to delay a wave or signal for a specific length of time.
DEPIC Dual Expanded Plastic Insulated Conductor (Foam Skin).  Decreases outside diameter of cable.
Derating Factor A multiplier used to reduce the current carrying capacity of conductors in more adverse environments, such as higher temperature, or where multiple conductors are together in one conduit.
DES Data Encryption Standard.
DHCP Dynamic Host Configuration Protocol.
Dielectric An insulating (non-conducting) medium. It is the insulating material between conductors carrying a signal in a cable. In coaxial cables it is between the center conductor and the outer conductor. In twisted pair cables it is the insulation between conductors plus any surrounding air or other material.
Dielectric Breakdown Any change in the properties of a dielectric that causes it to become conductive. Normally a catastrophic failure of an insulation because of excessive voltage.
Dielectric Constant Also called relative permittivity. That property of a dielectric which determines the amount of electrostatic energy that can be stored by the material when a given voltage is applied to it. Actually, the ratio of the capacitance of a capacitor using the dielectric to the capacitance of an identical capacitor using a vacuum (which has a dielectric constant of 1) as a dielectric. A number which indicates the quality of a material to resist holding an electrical charge when placed between two conductors.
Dielectric Heating The heating of an insulating material when placed in a radio-frequency field, 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 voltage an insulation can withstand before it breaks down. Usually expressed as "volts per mil".
Dielectric Withstand Voltage The voltage an insulation can withstand before it breaks down. Usually expressed as "volts per mil".
Digital Signal An electrical signal which possesses two distinct states (on/off, positive/negative).
Dispersion The cause of bandwidth limitations in an optical fiber. Dispersion causes a broadening of input pulses along the length of the fiber. Two major types are (a) mode dispersion caused by differential optical path lengths in a multimode fiber, and (b) material dispersion caused by a differential delay of various wavelengths of light in a wave guide material.
Distortion Any undesired change in a wave form or signal.
Distribution Cables In a CATV system, the transmission cable between the distribution amplifier and the drop cable.
Disturbed Conductor A conductor that receives energy generated by the field of another conductor or an external source. e.g. the quiet line.
DMT Discrete Multitone.
DOCSIS Data Over Cable Service Interface Specification (trade mark). Defines interface requirements for cable modems involved in high-speed data distribution over cable television system networks.
Drain Wire A non-insulated wire in contact with parts of a cable, usually the shield, and used in the termination to that shield and as a ground connection.
Driver A set of software routines used to control input and output from an operating system.
Drop Cable In a CATV system, the transmission cable from the distribution cable to a dwelling.
DSL Digital Subscriber Line.  A technology for bringing high-bandwidth information to homes and small businesses over ordinary copper telephone lines.  A DSL line can carry both data and voice signals, with the data part of the line remaining continuously connected.  Currently competes with the cable modem in bringing broadband services to homes and small businesses.
DTE (Data Terminal Equipment) - A generic name for user-owned devices, PCs, or stations that attach to a network.
Duobond II Belden trademark for a laminated shielding tape consisting of heat sensitive adhesive, aluminum foil, polyester or polypropylene, and aluminum foil.
Duofoil Belden trademark for a shield in which metallic foil is applied to both sides of a supporting plastic film.
DVB Digital Video Broadcasting.
E Voltage (electromotive force).
Earth British terminology for zero-reference ground.
Edge Margin Margin.
EFP Electronic Field Production. Video production for commercials, television shows and other non-news purposes done outside the studio.
EIA Electronic Industries Association (formerly RMA or RETMA).
Elastomer Any material that will return to its original dimensions after being stretched or distorted.
Electromagnetic Referring to the combined electric and magnetic fields caused by electron motion through conductors.
Electromagnetic Coupling The transfer of energy by means of a varying magnetic field. Inductive coupling.
Electron Volt A measure of the energy gained by an electron passing through an electric field produced by one volt.
Electrostatic Pertaining to static electricity, or electricity at rest. An electric charge, for example.
Electrostatic Coupling The transfer of energy by means of a varying electrostatic field. Capacitive coupling.
ELFEXT Equal Level Far End Crosstalk (dB). A subtraction of attenuation from FEXT. By subtracting the attenuation, ELFEXT negates the effects of attenuation on the interference as it propagates down the cable, thus bringing it to an "equal level".
Elongation The increase in length of a wire or cable cause by longitudinal tension.
EMF Electromotive force (voltage).
EMI Electromagnetic Interference.
Energy The capability of doing work.
Energy Dissipation Loss of energy from a system due to the conversion of work energy into an undesirable form usually heat. Dissipation of electrical energy occurs when current flows through a resistance.
ENG Electronic News Gathering.
EPDM Ethylene-propylene-diene monomer rubber. A chemically cross-linked elastomer with good electrical insulating properties and excellent flexibility at high and low temperatures. It has good insulation resistance and dielectric strength, as well as excellent abrasion resistance and mechanical properties. EPDM has better cut-through resistance than Silicone rubber, which it replaces in some applications.
EPR Ethylene-propylene copolymer rubber. A material with good electrical insulating properties.
Equilay More than one layer of helically laid wires with the length of the lay the same for each layer.
Ethernet The LAN technology that uses CSMA/CD physical access method and 10, 100 or 1000 Mbps digital transmission. The 10Gig Standard is in committee.
ETP Abbreviation for a copper refining process called Electrolytic Tough Pitch. This process produces a conductor that is 99.95% pure copper (per ASTM B115) resulting in high conductivity.
eV Electron volt.
Expanded Polyethylene Expanded or "foam" polyethylene, consists of individual closed cells of inert gas suspended in a polyethylene medium, resulting in a desirable reduction of the dielectric constant.
Extruded Cable Conductors are simultaneously insulated and the cable is formed by a continuous extrusion process.
f Frequency.
Farad A unit of capacity that will store one coulomb of electrical charge when one volt of electrical pressure is applied.
FAS Fire Alarm and Signal Cable, CSA (Canadian Standards Association) Cable Designation.
FAQ Frequently Asked Question.
FCFC Abbreviation for flat conductor flat cable.
FDDI Fiber Distributed Data Interface.
FEC Forward Error Correction.
Feedback Energy that is extracted from a high-level point in a circuit and applied to a lower level. Positive feedback reduces the stability of a device and is used to increase the sensitivity or produce oscillation in a system. Negative feedback, also called inverse feedback, increases the stability of a system as the feedback improves stability and fidelity.
Feeder Cable In a CATV system, the transmission cable from the head end (signal pickup) to the trunk amplifier. Also called a trunk cable.
FEP Fluorinated ethylene-propylene. A thermo-plastic material with good electrical insulating properties and chemical and heat resistance.
Ferrous Composed of and/or containing iron. A ferrous metal exhibits magnetic characteristics.
Ferrule A mechanical fixture, generally a rigid tube, used to protect and align a fiber in a connector. Generally associated with fiber optic connectors and made of ceramic material.
FEXT Far End Crosstalk. Crosstalk induced on the pairs, measured at the "far" end of the cable, referenced to the near end input signal. Usually expressed in decibels.
Fiber A single, separate optical transmission element characterized by core and cladding.
Fiber Optics Light transmission through optical fibers for communication and signaling.  A technology that transmits information as light pulses along a glass or plastic fiber.  Optical fiber carries much more information than conventional copper wire and is generally not subject to interference.  Most telephone company long-distance lines are optical fiber.  See RUS 1755.900.
Fiber to the home (FTTH) A technology that provides voice, data and video services from the phone company's branch office to local customers over an all-fiber optic link.  Still in its infancy, FTTH technology is substantially more expensive and labor-intensive to install and maintain than competing technologies.
Field An area through which electric and/or magnetic lines of force pass.
Filled Cables that are gel filled.
Fillers Nonconducting components cabled with the insulated conductors or optical fibers to impart roundness, flexibility, tensile strength, or a combination of all three, to the cable.
Flamarrest Belden trademark for a plenum grade chloride-based thermoplastic jacketing material with low smoke and low flame spread properties; more flexible than traditional fluorocopolymer jacket materials. Cables jacketed with Flamarrest meet the UL Standard 910, Plenum Cable Flame Test.
Flame Resistance The ability of a material not to fuel a flame once the source of heat is removed.
Flat Cable Also referred to as planar and/or ribbon cable. Any cable with two or more parallel conductors in the same plane encapsulated by insulating material.
Flat Conductor A conductor with a width-to-thickness ratio of arbitrarily 5 to 1 or greater.
Flat Conductor Cable A flat cable with a plurality of flat conductors.
Flex Life The qualification of the number of times a cable may bend before breaking.
Flexibility The ability of a cable to bend in a short radius. The ability of a cable to lay flat or conform to a surface as with microphone cables.
Floating Referring to a circuit which has no connection to ground.
Fluorocopolymer Generic term for PVDF.
FM Frequency modulation.
Foam Polyethylene Expanded or "foam" polyethylene, consists of individual closed cells of inert gas suspended in a polyethylene medium, resulting in a desirable reduction of the dielectric constant.
FOIRL (Fiber Optic Inter Repeater Link) - A fiber optic signaling method based on the IEEE 802.3 standard governing fiber optics connecting two LAN segments.
FR-TPE FR-TPE, flame retarded thermoplastic elastomer, is a rubber-like plastic that has properties similar to rubber yet is processed as a thermoplastic. It is used as the insulation and jacket in an all TPE construction which meets UL 13 and 1277 industrial cable requirements. It has good electrical properties, abrasion resistance, colorability and flame retardancy. This compound is ideal for cold weather applications.
FREP Flame retardant ethylene propylene is a special flame retardant version of EPDM rubber. It is designed for use as an industrial control insulation and has excellent electrical characteristics, deformation resistance, and also meets the flame retardant needs of industrial control cables.
Frequency The number of times a periodic action occurs in one second. Measured in Hertz.
Frequency Response The amplitude versus frequency characteristics of a device. Also may refer to the range of frequencies over which the device operates within prescribed performance
Frequency, Power Normally, the 50 or 60 hertz power used to operate most AC powered equipment. The frequency of AC power supplied by electric utilities companies.
FSK Frequency Shift Keying.
FTTC Fiber-to-the-Curb.
Fusion Splice A permanent joint produced by the application of localized heat sufficient to fuse or melt the ends of the optical fiber, forming a continuous single fiber.
Gage The physical diameter of a wire. A standard for expressing wire diameter. As the AWG number gets smaller, the wire diameter gets larger.
Gain The increase of voltage, current, or power over a standard or previous reading. Usually expressed in decibels.
Geosol A solderable, extra tough film insulation developed b Belden for use in geophysical cables and miniature cables.
Giga One billion.
Gigahertz (GHz) A unit of frequency equal to one billion hertz.
GND Ground.
Gopher Gopher Resistant Copper Alloy.  Provides shield and added protection in a single layer.
GOPIC Gopher.
Graded-Index A type of optical fiber in which the refractive index of the core is in the form of a parabolic curve, decreasing toward the cladding. This type of fiber provides high bandwidth capabilities.
Ground An electrical connection between a circuit and the earth. Also refers to a conductor connected to earth. In some instances, can refer to a central metallic point designated as having "zero" potential.
Ground Conductor A conductor in a transmission cable or line that is grounded.
Ground Loop A completed circuit between shielded pairs of a multiple pair created by random contact between shields. An undesirable circuit condition in which interference is created by ground currents when grounds are connected at more than one point.
Ground Potential The potential of the earth. A circuit, terminal, or chassis is said to be at ground potential when it is used as a reference point for other potentials in the system.
H Symbolic designation for magnetic field intensity. Abbreviation for henrys (unit of inductance).
Halar Thermoplastic fluoropolymer material with excellent chemical resistance, electrical properties, thermal characteristics, and impact resistance.
Haloarrest I Haloarrest I is a non-halogenated flame retarded thermoplastic polyolefin with excellent low smoke and flame properties. It is used as a jacket over the XLPE insulated singles (non-XHHW), and the entire construction meets the UL 13 and 1277 specifications as a non-halogenated PLTC/TC cable. Haloarrest I meets the European Specifications on acid gas evolution and % Halogen content. This jacket can also be used with XHHW conductors for wet ratings.
Harness A flat cable or group of cables, usually with many breakouts with the wire ends prepared for termination or terminated to connectors and ready to install.
HDSL High bit-rate Digital Subscriber Line.
Headroom The amount by which a cable ACR exceeds the specified requirements. The TIA/EIA 568B standard specifies a minimum of 10 dB of ACR for Category 5e certification at 100 MHz.
Henry Unit of inductance (H) that will produce a voltage drop of one volt when the current changes at the rate of one ampere per second.
Hertz (Hz) Unit of frequency equal to one cycle per second.
Heterogeneous Insulation A cable insulating system composed of two or more layers of different insulating materials.
HF High Frequency. International Telecommunication Union designation for the 3-30 MHz band of frequencies.
HFC Hybrid Fiber/Coaxial.
High Frequency International Telecommunication Union designation for the 3-30 MHz band of frequencies.
Homogeneous Insulation A complete cable insulation structure whose components cannot be identified as layers of different materials.
Hook-Up Wire Single conductor wire with various types of insulation.
Horizontal Cable Cable used between the workstation outlet and the telecommunications closet. Limited to 90 meters maximum per TIA/EIA 568B.1.
HSCDS High-Speed Cable Data Service.
HTML Hypertext Markup Language.
HTTP Hypertext Transfer Protocol.
Hub The central switch in a twisted pair network. All nodes on the network are connected via point-to-point lines to the hub (Star Topology).
Hub MIB A specification that defines an experimental portion of the Management Information Base for use with network managing protocols in TCP/IP based internets.
Hum Term used to describe noise in a audio, video, or other system that comes from 60 Hz power or its harmonic(s). So named for the low-frequency humming sound produced in audio systems. Usually hum is the result of undesired coupling from a 60 Hz source or of inadequate filtering of the DC output of an AC input power supply.
Hypalon A DuPont trade name for a synthetic rubber (chlorosulfonated polyethylene) used as insulating and jacketing material for wire and cable.
I Symbol used to designate current.
I/O Interconnection Input/Output interface to the "outside world."
I2R Formula for power in watts, where I=current in amperes, R=resistance in ohms.
ICEA Insulated Cable Engineers Association.
IDC Insulation Displacement Connector. Type of connector where contact is made to the cable conductor(s) by cutting through the individual conductor's insulation. The conductor does not need to have its insulation removed prior to connection. Flat cable often uses IDCs to simultaneous connect all conductors.
IDSL ISDN Digital Subscriber Line.
IEEE Institute of Electrical and Electronic Engineers.
IEEE 802.3 A physical layer standard that uses the CSMA/CD access method on a bus topology LAN.
IETF Internet Engineering Task Force.
IF Intermediate Frequency.
IFB Interrupted Feedback (Foldback). Interruptible Feedback (Foldback). A monitoring scheme often used in television where the feed of program audio to an on-air person can be interrupted with directions, cues, or other information. Usually integrated into the intercom system.
IGMP Internet Group Management Protocol.
Impedance The total opposition that a circuit offers to the flow of alternating current or any other varying current at a particular frequency.
Impedance Match A condition whereby the impedance of a particular circuit cable or component is the same as the impedance of the circuit, cable, or device to which it is connected.
Impedance Matching Sub A section of transmission line or pair of conductors cut to match the impedance of a load. Also called matching sub.
Impedance Matching Transformer A transformer designed to match the impedance of one circuit to that of another.
Impedance, Characteristic In a transmission cable of infinite length, the ratio of the applied voltage to the resultant current at the point the voltage is applied. Or the impedance which makes a transmission cable seem infinitely long, when connected across the cable's output terminals.
Impedance, High Generally, the area of 25,000 ohms or higher.
Impedance, Low Generally, the area of 1 through 600 ohms.
Index Edge Reference Edge.
Inductance The property of wire which stores electrical current in a magnetic field around the wire. By coiling wire, the effect can be intensified. It is measured in Henrys.
Induction The phenomenon of a voltage, magnetic field, or electrostatic charge being produced in an object from the source of such fields.
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 losses account for the resultant heat.
Inductive Crosstalk Crosstalk resulting from the coupling of the electromagnetic field of one conductor upon another.
Injection Laser Diode Sometimes called the semiconductor diode. A laser in which the lasing occurs at the junction of n-type and p-type semiconductor materials.
INMS Integrated Network Management System.
Input A signal (or power) which is applied to a piece of electric apparatus or the terminals on the apparatus to which a signal or power is applied.
Insertion Loss A measure of the attenuation of a cable and/or component(s) by determining the output of a system before and after the device is inserted into the system.
Insulation A material having good dielectric properties which is used to separate close electrical components, such as cable conductors and circuit components.
Insulation Displacement Connector (IDC) A mass termination connector for flat cable with contacts that displace the conductor insulation to complete termination.
Insulation Stress The molecule separation pressure caused by a potential difference across an insulator. The practical stress on insulation is expressed in volts per mil.
Interface The region where two systems or a major and a minor system meet and interact with each other.
Interface Layer The layer in the Internet suite of protocols responsible for transmission on a single physical network.
Interference Disturbances of an electrical or electromagnetic nature that introduce undesirable responses into other electronic equipment.
Intermediate Frequency A frequency to which a signal is converted for ease of handling. Receives its name from the fact that it is an intermediate step between the initial and final conversion or detection stages.
Internet A collection of networks that are interconnected by linking devices such as bridges, routers, and gateways to operate as a single large network.
Internetworking Communication among devices across multiple networks.
Interoperability The process whereby computers can operate interactively with each other across a network without data conversion or human intervention.
Ionization The formation of ions. Ions are produced when polar compounds are dissolved in a solvent and when a liquid, gas, or solid is caused to lose or gain electrons due to the passage of an electric current.
Ionization Voltage The potential at which a material ionizes. The potential at which an atom gives up an electron.
IP Internet Protocol.
IPCDN IP Over Cable Data Network working group of the IETF.
IPX (Internetwork Packet Exchange) - A network layer protocol developed by Novell, Inc. and used in NetWare implementations.
IR Insulation Resistance.
IR Drop The designation of a voltage drop in terms of current and resistance. See also Voltage Drop.
IRC Inter Relay Chat.
IRS Ignition radiation suppression.
ISDN Integrated Services Digital Network.  An alternative to telephone modems that allows digital transmission over ordinary telephone copper wire and other media.  Home and business users can get highly graphic Web pages more quickly through ISDN adapters than through dial-up connections.
ISO International Standards Organization.
Isolation The ability of a circuit or component to reject interference, usually expressed in dB.
ISP Internet Service Provider.
ITFS Instructional Television Fixed Service.
ITU International Telecommunications Union.
Jacket Pertaining to wire and cable, the outer protective covering that may also provide additional insulation.
Jumper A short length of conductor or flat cable used to make a connection between terminals or around a break in a circuit, or between circuit boards.
kB Kilobyte.
keV 1000 electron volts.
Kevlar See Aramid Fiber. This is the same material as used in bullet-proof vests.
Kilo One thousand.
KPSI Tensile strength in thousands of pounds per square inch.
kV Kilovolt (1000 volts).
kVA Kilo Volt-ampere. One thousand volt-amperes (VA). See also VA.
kW Kilowatt.
L Symbol for inductance.
Laminated Cable Insulated or uninsulated wires which are encapsulated by two sheets of laminate material to maintain a predetermined pitch.
LAN Local Area Network. A data network connecting any number of users, intended to serve a small area. A group of computers and associated devices that share a common communications line and typically share the resources of a single processor or server within a small geographic area.
Laser A coherent source of light with a narrow beam and a narrow spectral bandwidth (about 2nm).
Lay The length measured along the axis of a wire or cable required for a single strand (in stranded wire) or conductor (in cable) to make one complete turn about the axis of the conductor or cable. In a twisted pair cable, the lay length is the distance it takes for the two wires to completely twist around each other.
Lay Direction The direction of the progressing spiral twist in a cable while looking along the axis of the cable away from the observer. The lay direction can be either "left" or "right".
Layer A conceptual level of network processing functions defined by OSI model. Processing takes place in layers starting from the physical transmission of data up through to the commands of an end-user (the ISO Seven Layer Model).
Lead Dress The placement or routing of wiring and component leads in an electrical circuit.
Lead-in The cable that provides the path for r-f energy between the antenna and the receiver or transmitter.
Leakage The undesirable passage of current over the surface of or through an insulator.
Learning Bridge A bridge which automatically "learns" the topology of the LAN addresses of each node as it receives packets. Requires little or no setup at time of installation. These have largely been replaced by Switches and Routers.
LEC Local Exchange Carrier.
LED (Light Emitting Diode) - A solid state device that radiates light a single frequency through plastic (POF) or glass.
Level A measure of the difference between a quantity or value and an established reference.
LF Low frequency.  International Telecommunication Union designation for the 30-300 kHz band of frequencies.
Light Emitting Diode (LED Source) A semiconductor device that emits incoherent light formed by the P-N junction. Light intensity is roughly proportional to electrical current flow.
Limpness The ability of a cable to lay flat or conform to a surface as with microphone cables. The ability of a cable to bend in a short radius.
Line Drop A voltage loss occurring between any two points in a power or transmission line. Such loss, or drop, is due to the resistance, reactance, or leakage of the line. See also Voltage Drop and IR Drop.
Line Equalizer A reactance (inductance and/or capacitance) connected in series with a transmission line to alter the frequency-response characteristics of the line.
Line Level Refers to the output voltage level of a piece of electronic equipment. Usually expressed in decibels (e.g.. 0 dBV).
Line Voltage The value of the potential existing on a supply or power line.
LMDS Local Multipoint Distribution Service
Load A device that consumes power from a source and uses that power to perform a function.
Loaded Line A transmission line that has lumped elements (inductance or capacitance) added at uniformly spaced intervals. Loading is used to provide a given set of characteristics to a transmission line.
Loading 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.
Local Area Network A data network connecting any number of users, intended to serve a small area. See also LAN.
Long-wire Antenna An antenna conductor length in excess of one-half of a wavelength.
Loose Tube Cable Type of cable design whereby coated fibers are encased in buffer tubes offering excellent fiber protection and segregation.
Loss Energy or signal lost without accomplishing useful work.
Lossy Having high losses resulting in efficiency.
Low Frequency International Telecommunication Union designation for the 30-300 kHz band of frequencies.
Luminance Signal The portion of the composite video signal that represents the brightness or the black and white information.
m Prefix for milli or one-thousandth.
M Mutual inductance. The abbreviation for mega or 1 million. And also indicates 1000 (one thousand) feet in the wire industry. Lower case m is for milli or one-thousandth. See also m.
M' Notation representing 1000 feet.
mA milliampere (one-thousandth of an ampere).
MAC Media Access Control (layer of OSI Reference Model).
MAN Metropolitan Area Network. A data network intended to serve the area of a city or an area of similar size.
Manufacturing Automation Protocol A manufacturing automation protocol based on IEEE 802.4 standards.
MAP Manufacturing Automation Protocol. A manufacturing automation protocol based on IEEE 802.4 standards.
Margin Distance between reference edge of cable and nearest edge of first conductor or center of first conductor.
Mass-Termination The process of simultaneously terminating all conductors in a single operation.
Master Station A station or network node that maintains direct control over other stations or nodes.
Matte Finish PVC A special formulation of PVC which very closely looks and feels like rubber.
MATV Abbreviation for Master Antenna Television.
MAU (Medium Attachment Unit) - A device used to attach a processing node to a network at the physical level. An example is the transceiver used to attach devices to an Ethernet cable.
MB Megabyte.
Mbps Mega bits per second - the number of bits, in millions, transmitted per second.
MCNS Multimedia Cable Network System Partners Ltd.
MDS Multipoint Distribution System.
Media Converters These are active (powered devices) that change LAN traffic from one media to another such as copper cable to fiber cable. They do not induce delay in the transmission, and are "transparent" to the packet. See the BL-5270 and BL-270 series.
Medium A physical conduit for data transmission, e.g., coaxial cable or radio waves.
Mega Prefix meaning million.
Megahertz (MHz) Unit of frequency equal to one million hertz.
Metropolitan Area Network A data network intended to serve the area of a city or an area of similar size. See also MAN.
mfd Microfarad (one-millionth of a farad). Modern abbreviation is uF (lower case Green mu followed by F).
Mho The unit of conductance equal to the reciprocal of the unit of resistance (ohm).
MHz Megahertz (see also).
MIB (Management Information Base) - A collection of objects that can be accessed via a network management protocol.
Micro Prefix meaning one-millionth.
Microfarad One-millionth of a farad (uf, ufd, mf, and mfd are common abbreviations).
Micromicrofarad One-millionth of a microfarad (uuf, uufd, mmf, mmfd are common abbreviations). Modern usage is picofarad (pF).
Micron Millionth of a meter.
Microphonics Noise caused by mechanical excitation of a system component. In a single-conductor microphone cable, for example, microphonics can be caused by the shield rubbing against the dielectric as the cable is flexed.
Mil A unit of length equal to one thousandth of an inch (.001").
Milli Prefix meaning one-thousandth.
MMDS Multichannel Multipoint Distribution System.
Mode A single electromagnetic wave traveling in an optical fiber.
Modem Modulator-Demodulator. Device that converts signals in one form to another form compatible with another kind of equipment.
Modulation Altering the characteristics of a carrier wave to convey information. Modulation techniques include amplitude frequency, phase, plus many other forms of on-off digital coding.
Molded Cable Cable assemblies with molded connectors on one or both ends.
Mono Filament A single strand filament as opposed to a braided or twisted filament.
MSO Multiple System Operator. Cable TV term referring to companies that operator multiple cable TV systems in numerous cities.
MTP Simple Mail Transfer Protocol.
Multi-Conductor Cable Cable with more than one conductor.
Multifiber Cable An optical fiber cable that contains two or more fibers.
Multimode Fiber An optical waveguide in which light travels in multiple modes. Typical core/cladding size (measured in micrometers) is 50 or 62.5/125.
Multiplex A technique for putting two or more signals into a single channel.
Multiport Repeater A repeater that collects signals from one transmission channel and, after performing the standard repeater functions, retransmits the signals to more than one new transmission channel.
Mutual Capacitance Effective capacitance between two conductors when the effects of the other conductors and shield, if present, are removed.
mV Millivolt (one-thousandth of a volt).
mW Milliwatt (one-thousandth of a watt).
Mylar DuPont trademark for polyethylene terephtalate (polyester) film.
N Type of coaxial connector named after its inventor, Paul Neil of Bell Labs.
Nano One-billionth.
Nanometer (nm) One billionth of a meter.
Nanosecond One billionth of a second.
NAP Network Access Point.
National Electrical Code (NEC) A publication of the National Fire Protection Association (NFPA) which outlines requirements for electrical wiring and building construction.
NBR Butadiene-acrylonitrile copolymer rubber, a material with good oil and chemical resistance.
NEC National Electrical Code. A publication of the National Fire Protection Association (NFPA) which outlines requirements for electrical wiring and building construction.
NEMA National Electrical Manufacturers Association.
Neoprene A synthetic rubber with good resistance to oil, chemical, and flame. Also called polychloroprene.
NetWare A network operating system implementation and control approach developed by Novell, Inc. that defines the network architecture and the software modules needed for network operation. Also the name of the network software.
Network A network is a method of data communications between computers.
Network Layer The layer in the OSI model that is responsible for ensuring that data passed to it from the transport layer is routed and delivered through the network.
Network Redundancy The state of having more connecting links than the minimum required to provide a connecting path between all nodes.
Network Topology The physical and logical relationship of nodes in a network typically of either a star, ring, tree, or bus topology, or some hybrid combination thereof.
NEXT Near-end Crosstalk. Crosstalk induced on the pairs, measured at the end "near" the transmitter. Usually expressed in decibels.
NFPA National Fire Protection Association.
Nibble One half byte (4 bits).
NOC Network Operations Center.
Node A point where one or more functional units interconnect transmission lines.
Noise In a cable or circuit, any extraneous signal which tends to interfere with the signal normally present in or passing through the system.
Nomex DuPont trademark for a temperature-resistant, flame-retardant nylon.
Non-Paired Cable Cable with two or more cabled conductors that are not in a paired configuration.
Non-Plenum A description for a cable that does not meet the requirements of UL 910 CMP flame test. Such a cable cannot be installed in an area that is used for air return (plenum).
Notch The removal of the web section between conductors of a flat cable to aid in stripping, slitting, and termination.
NTSC National Television System Committee.  Organization that formulated standards for the current U.S. color television system. This system is used in most countries of the Americas and in other parts of the world. It was designed to be compatible with the existing monochrome TV sets, so that they would not become obsolete. Color televisions would also be able to receive monochrome transmissions. NTSC uses a 3.579545 MHz subcarrier whose phase varies with the instantaneous hue of the televised color and whose amplitude varies with the instantaneous saturation of the color. NTSC employs 525 lines per frame, 29.97 frames per second and 59.94 fields per second.
Numerical Aperture (NA) A measure of the angular acceptance for a fiber. It is approximately the sine of the half-angle of the acceptance cone.
Nylon An abrasion-resistant thermoplastic with good chemical resistance.
OFDM Orthogonal Frequency Division Multiplexing.
OFHC Abbreviation for oxygen-free, high conductivity copper. It has 99.95% minimum copper content and an average annealed conductivity of 101% compared to standard copper.
Ohm The unit of electrical resistance. The value of resistance through which a potential difference of one volt will maintain a current of one ampere.
Ohm's Law Stated E=IR, I=E/R or R=E/I. The current I in a circuit is directly proportional to the voltage E, and inversely proportional to the resistance R.
Optical Waveguide Fiber A transparent filament of high refractive index core and low refractive index cladding that transmits light.
OSI Open System Interconnect (Model for networking protocols).
OSS Operations Support Systems.
Output The useful power or signal delivered by a circuit or device.
Ozone Extremely reactive form of oxygen, normally occurring around electrical discharges and present in the atmosphere in small but active quantities. In sufficient concentrations is can break down certain rubber insulations under tension (such as a bent cable).
Packet The basic unit of data transfer in LANs.
Packet Switching A method of transmitting massages through a communications network in which long messages are subdivided into short packets.
Paired Cable Cable with conductors cabled in groups of two.
PAL Phase Alternation Line. PAL is a European color TV system featuring 625 lines per frame, 25 frames and 50 fields per second. Used mainly in Europe, China, Malaysia, Australia, New Zealand, the Middle East, and parts of Africa. PAL-M is a Brazilian color TV system with 525 lines per frame, 30 frames and 60 fields per second.
Parallel Circuit A circuit in which the identical voltage is presented to all components, with current dividing among the components according to the resistances or the impedances of the components.
Parallel Digital Digital information that is transmitted in parallel form. The digits are sent on separate conductors rather than sequentially on one transmission line (serial). Often used informally to refer to parallel digital television signals.
PASP Polyethylene Aluminum Steel Polyethylene.  provides additional lightning and gopher protection.
Patchcord A flexible piece of cable terminated at both ends with plugs. Used for interconnecting circuits on a patchboard, in a wiring closet, or at the work area.
PC Personal Computer.
PE Polyethylene.
Peak The maximum instantaneous value of a varying current or voltage.
Peel Strength The force necessary to separate two adjacent conductors of a bonded or laminated flat cable.
Periodicity The uniformly spaced cable impedance variations that result in addition of the reflections of a signal. The distance between them is the half wavelength most affected. Multiples of that frequency are also affected. Even very slight variations, which appear over and over in a construction or installation, can have major effects on signal integrity because of periodicity.
Permanent Link The horizontal cable including the workstation outlet and patch panel in the telecommunications closet plus two meters of cable at each end for testing. Limited to a maximum of 90 meters in TIA/EIA 568B.1.
Phase An angular relationship between waves.
Phase Shift A change in the phase relationship between two alternating quantities.
Photodetector (Receiver) Converts light energy to electrical energy. The silicon photo diode is most commonly used for relatively fast speeds and good sensitivity in the 0.75 micron to 0.95 micron wavelength region. Avalanche photodiodes (APD) combine the detection of optical signals with internal amplification of photo-current. Internal gain is realized through avalanche multiplication of carriers in the junction region. The advantage in using an APD is its higher signal-to-noise ratio, especially at high bit rates.
PHY Physical (layer of OSI Reference Model). See also Physical Layer.
Physical Layer The actual portion of a network that is used to physically connect computers of a network and over which the data is transmitted - the cable.
PIC Plastic Insulated Conductor.  Provides strong insulation.
Pickup Any device which is capable of transforming a measurable quantity of intelligence (such as sound) into relative electrical signals (e.g., a microphone).
Pico One-trillionth.
Picofarad One trillionth of a farad. A micromicrofarad. Abbreviated pF in modern usage or mmF in earlier usage.
Pin-diode A photodetector used to convert optical signals to electrical signals in a receiver. See also Photodetector.
Pitch Nominal distance from center-to-center of adjacent conductors within a cable. When conductors are flat, pitch is usually measured from the reference edge of a conductor to the reference edge of the adjacent conductor. Spacing.
Planar Cable Also referred to as flat and/or ribbon cable. Any cable with two or more parallel conductors in the same plane encapsulated by insulating material.
Plastic High polymeric substances, including both natural and synthetic products that are capable of flowing under heat and pressure, called thermoplastics. Unlike rubber and other thermoset compounds, plastics can be remelted and reused.
Plasticizer A chemical added to plastics to make them softer and more flexible.
Plenum A compartment or chamber to which one or more air ducts are connected and that forms part of the air distribution system. A description for a cable that passes the UL 910 CMP flame test requirements.
Plug A male housing with male or female contacts.
PoE Power over Ethernet.
Point-to-Point Wiring Wiring that consists of continuous conductors terminated at each end to circuit destination.
Polarization The orientation of a flat cable or a rectangular connector. e.g., for gray flat cable, the colored edge indicating the number one conductor.
Polybutadiene A type of synthetic rubber often blended with other synthetic rubbers to improve their properties.
Polyethylene A thermoplastic material having excellent electrical properties. Low dielectric constant, a stable dielectric constant over all frequencies, very high insulation resistance. In terms of flexibility, polyethylene can be rated stiff to very hard, depending on molecular weight and density - low density being the most flexible and the high-density, high-molecular weight formulation being very hard. Moisture resistance is rated excellent.
Polymer A substance made of many repeating chemical units or molecules. The term polymer is often used in place of plastic, rubber, or elastomer.
Polyolefin Any of the polymers and copolymers of the ethylene family of hydrocarbons, such as polyethylene and polypropylene.
Polypropylene A thermoplastic similar to polyethylene but stiffer and having a higher softening point (temperature). This material is primarily used as an insulation material. Typically, it is harder than polyethylene. This makes it suitable for thin wall insulations. The dielectric constant is 2.25 for solid and 1.55 for cellular designs.
Polyurethane (PUR) Broad class of polymers noted for good abrasion and solvent resistance. Can be in solid or cellular form. This thermoplastic material is used primarily as a cable jacket material. It has excellent oxidation, oil, and ozone resistance. Some formulations also have good flame resistance. It is a hard material with excellent abrasion resistance. It has outstanding "memory" properties, making it an ideal jacket material for retractile cords.
Polyvinyl chloride A general purpose thermoplastic used for wire and cable insulation and jackets.
Portable Cordage Cable with two or more twisted conductors for flexible applications.  Also called flexible cord.
POTS Plain Old Telephone Service. Sometimes used in discussions of new telephone technologies in which the question of whether and how existing voice transmission for ordinary telephone communication can be accommodated.  For example, DSL and ISDN provide part of their channels for POTS, while using most of their bandwidth for digital data transmission.
Potting Sealing by filling with a substance to exclude moisture.
Power The amount of work per unit of time. Usually expressed in watts. Power equals the product of voltage and current (P=V*I).
Power Loss The difference between the total power delivered to a circuit, cable, or device and the power delivered by that device to a load.
Power Ratio The ratio of power appearing at the load to the input power.
PP Polypropylene.
PPP Point-to-Point Protocol.
Precision Video Video coaxial cables having very tight electrical tolerances in impedance, velocity of propagation, attenuation and structural return loss. Used in high quality applications such as live broadcast in network studios and pre- or post-production facilities.
Premise Cabling Refers to the entire cabling system used for voice, data, video and power on a user's premise.  For Local Area Networks, the cabling of choice includes unshielded twisted pairs (UTP), fiber optic and coaxial cables.  Of these, the UTP market is the largest, with greatest demand for cables with four pairs that meet certain standards of performance, such as Category 5 and Category 5e.
PRI Primary Rate Interface ISDN.
Propagation Delay Time required for a signal to pass from the input to the output of a device.
Pseudo Random NRZ A wave form of binary signals that may be used in a computer system. It is called NRZ, Non-Return to Zero, because the voltage does not return to zero after each bit.
PSTN Public Switched Telephone Network.
Pulse A current or voltage which changes abruptly from one value to another and back to the original value in a finite length of time. Used to describe one particular variation in a series of wave motions.
Putup Packaging of finished wire or cable.
PVC Polyvinyl chloride (see also).
PVDF Polyvinylidene Fluoride.
QAM Quandrature Amplitude Modulation.
QOS Quality of Service.
QPSK Quaternary Phase Shift Keying or Quadrature PSK.
Quad A four conductor cable. Also called "star quad".
R Symbol for resistance.
R-F Radio-frequency.
Radio Frequency (RF) Radio Frequency. Includes frequencies from a few kilohertz to several hundred gigahertz. Used to transmit information from point to point over the airwaves or down coaxial cable.
RAM Random Access Memory.
Rated Temperature The maximum temperature at which an electric component can operate for extended periods without loss of its basic properties.
Rated Voltage The maximum voltage at which an electric component can operate for extended periods without undue degradation or safety hazard.
RDC Regional Data Center.
Reactance A measure of the combined effects of capacitance and inductance on an alternating current. The amount of such opposition varies with the frequency of the current. The reactance of a capacitor decreases with an increase in frequency; the opposite occurs with an inductance.
Receiver An electronic package that converts light energy to electrical energy in a fiber optic system. Also refers to a unit that converts an RF signal to another type of signal (e.g. radio, television). See also Photodetector.
Receptacle A female housing with male or female contacts.
Reference Edge Edge of cable or conductor from which measurements are made, such as in flat cable. Sometimes indicated by a thread, identification stripe, or printing. Conductors are usually identified by their sequential position from the reference edge, with number one conductor closest to this edge.
Reflectance Reflectance is the ratio of power reflected to the incident power at a connector junction or other component or device, usually measured in decibels or dB. Reflectance is stated as a negative value, e.g. -30 dB. A connector that has a better reflectance performance would be a -40 dB connector or a value less than -30 dB.
Reflection The change in direction (or return) of waves striking a surface. For example, electromagnetic energy reflections can occur at an impedance mismatch in a transmission line, causing standing waves.
Reflection Loss The part of a signal which is lost due to reflection of power at a line discontinuity.
Refractive Index The ratio of light velocity in a vacuum to its velocity in the transmitting medium.
Registration Alignment of one object with relation to another. In flat cables it involves aligning conductors with contacts or solder pads. Also called register.
Repeater A receiver and transmitter combination used to regenerate an attenuated signal.
Resistance In dc circuits, the opposition a material offers to current flow, measured in ohms. In ac circuits, resistance is the real component of impedance, and may be higher than the value measured at dc.
Resonance An ac circuit condition in which inductive and capacitive reactances interact to cause a minimum or maximum circuit impedance.
Retractile Cord A cord having specially treated insulation or jacket so that it will retract like a spring. Retractibility may be added to all or part of a cord's length.
Return Loss Measure of signal reflections from a cable or device with a fixed, standard reference impedance on the measuring equipment. Expressed in decibels.
RF Radio Frequency.
RFI Radio Frequency Interference.
RFP Request for Proposals.
RG/U RG is the abbreviation for radio guide, a military designation for a coaxial cable, and U stands for universal.
RGB Abbreviation for the three parts of color video signal: red, green and blue. Also refers to multi-coaxial cables carrying these signals.
Ribbon Cable A flat cable made with parallel round conductors in the same plane. Also referred to as planar and/or flat cable. Any cable with two or more parallel conductors in the same plane encapsulated by insulating material.
Ringing Out The process of locating or identifying specific conductor paths by means of passing a current through selected conductors.
RJ-45 Modular telecommunications connector.
RL Return Loss.
RMS Root-mean-square.
Rope Strand A conductor composed of groups of twisted strands.
Round Conductor Flat Cable (RCFC) A cable made with parallel round conductors in the same plane.
Routing The path followed by a cable or conductor.
RSVP Resource Reservation Protocol.
RTP Real-Time Transport Protocol.
Rubber (Wire Insulation) A general term used to describe wire insulations made of thermosetting elastomers, such as natural or synthetic rubbers, neoprene, Hypalon, butyl rubber, and others.
RUS 1755.900 (aka PE90) A specification for fiber optic cables currently in high demand by the telecommunications industry.  Only a handful of U.S. manufacturers can produce fiber optic cables to this specification.  Belden is one of them.
S-CDMA Synchronous Code Division Multiple Access.
S-HDSL Single-pair High bit-rate Digital Subscriber Line.
SAE Society of Automotive Engineers.
SBR A copolymer of styrene and butadiene. Also GR-S or Buna-S. Most commonly used type of synthetic rubber.
ScTP Screened Twisted Pair. Premise network cable with an overall foil shield.
SDI Serial Digital Interface.
SDSL Symmetric Digital Subscriber Line.
SEALPIC Aluminum Shield.  Sealed Aluminum.
Self-extinguishing The characteristic of a material that extinguishes its own flame after the igniting flame is removed.
Self-Support Undulated core with aluminum, polyethylene and a support strand.  For aerial use.
Semi-Solid Dielectric A coaxial design in which a monofilament of plastic holds the center conductor in place in a hollow plastic tube allowing the remainder of the dielectric to be air. Typical velocities of up to 84% can be achieved in this design.
Semiconductor In wire industry terminology, a material possessing electrical conductivity that falls somewhere between that of conductors and insulators. Usually made by adding carbon particles to an insulator. Not the same as semiconductor materials such as silicon, germanium, etc. Used for making transistors and diodes.
Separator Pertaining to wire and cable, a layer of insulating material such as textile, paper, Mylar, etc., which is placed between a conductor and its dielectric, between a cable jacket and the components it covers, or between various components of a multiple-conductor cable. It can be utilized to improve stripping qualities, flexibility, or can offer additional mechanical or electrical protection to the components it separates.
Serial Digital Digital information that is transmitted in serial form. SDI informally refers to serial digital television signals that conform to the SMPTE 259M standard. See also Serial Digital Interface.
Serial Digital Interface Informally refers to serial digital television signals that conform to the SMPTE 259M standard.
Series Circuit A circuit in which the components are arranged end to end to form a single path for current.
Serve Shield A metallic shield consisting of several strands of wire, helically wound and laid parallel around a cable core in only one direction, as opposed to the two directions with interleaving of a braid shield.
Sheath Pertaining to wire and cable, the outer protective covering, also called jacket, that may also provide additional insulation.
Shield A tape, serve or braid (usually copper, aluminum, or other conductive material) placed around or between electric circuits or cables or their components, to prevent signal leakage or interference.
Shield Coverage The optical percentage of a cable actually covered by shielding material.
Shield Effectiveness The relative ability of a shield to screen out undesirable interference or prevent signal leakage out of the cable. Frequently confused with the term shield coverage.
Shield Percentage The percentage of physical area of a circuit or cable actually covered by shielding material.
Shielded Armored Types of Shield: Aluminum, Aluminum/Steel, Gopher, and Copper.  Cables that require some sort of shield.
Signal Any visible or audible indication which can convey information. Also, the information conveyed through a communication system.
Signal Conductor A conductor in a transmission cable or line that carries electrical signals.
Signal to Noise Ratio Ratio of desired signal to undesired signal (noise) that is often expressed in decibels. Commonly used interchangeably with Attenuation Crosstalk Ratio (ACR) - the difference between attenuation and crosstalk, measured in decibels, at a given frequency. Important characteristic in networking transmission to assure that signal sent down a twisted pair is stronger at the receiving end of the cable than are any interference signals imposed on that same pair by crosstalk from other pairs.
Silicone General Electric trademark for a material made from silicon and oxygen. Can be in thermosetting elastomer or liquid form. The thermosetting elastomer form is noted for high heat resistance. This is a very soft thermoset insulation. It has excellent electrical properties plus ozone resistance, low moisture absorption, weather resistance, and radiation resistance. It typically has low mechanical strength and poor scuff resistance.
Single Mode Fiber A fiber wave guide in which only one mode will propagate. The fiber has a very small core diameter of approximately 8 micro meters. It permits signal transmission at extremely high bandwidths and is generally used with laser diodes.
Single-ended Unbalanced, such as grounding one side of a circuit or transmission line.
Sinusoidal Varying in proportion to the sine of an angle or time function. Ordinary alternating current is sinusoidal.
Skew Rays A ray that does not intersect the fiber axis. Generally, a light ray that enters the fiber core at a very high angle.
Skin Effect The tendency of alternating current to travel only on the surface of a conductor as its frequency increases.
SMA Subminiature A connector commonly used in VHF, UHF, and microwave RF applications.
SMB Subminiature B connector snap-mount connector.
SMC Subminiature C connector.
Snake Cable A name given to individually shielded or individually shielded and jacketed, multi-pair audio cables. Used in the connection of multi-channel line level audio equipment.
SNMP Simple Network Management Protocol.
SNR Signal to Noise Ratio (see also).
SONET Synchronous Optical Network.
Source The device (usually LED or laser) used to convert an electrical information-carrying signal into a corresponding optical signal for transmission by an optical wave guide.
Spacing The distance between the centers of two adjacent conductors. Pitch.
Span The distance between the center of the first conductor and the center of the last conductor in a flat cable.
Spectral Bandwidth The difference between wavelengths at which the radiant intensity of illumination is half its peak intensity.
Spectrum Frequencies that exist in a continuous range and have a common characteristic. A spectrum may be inclusive of many spectrums (e.g., the electromagnetic radiation spectrum includes the light spectrum, radio spectrum, infrared spectrum, etc.).
Speed of Light ( c ) Approximately 2.998 x 10^8 meters per second.
Splicing The permanent joining of bare fiber ends to another fiber. See Fusion Splice and Mechanical Splicing.
Splitter A device that send the signal from one source to two or more receiving devices by allocating a portion of the signal to each receiver (e.g. cable TV splitter). A device that divides a high bandwidth signal into two or more lower bandwidth signals, each carrying a selected frequency range.  Users connected to a DSL line, for example, may have a splitter installed at their home or business to divide the incoming signal into low frequencies to send to their phone and high frequencies for data to the computer.
SRL Structural Return Loss.
Stalpeth (DUCTPIC) Aluminum steel bonded to the polyethylene jacket.  Helps minimize jacket damage.
Standing Wave The stationary pattern of waves produced by two waves of the same frequency traveling in opposite directions on the same transmission line. The existence of voltage and current maxima and minima along a transmission line is a result of reflected energy from an impedance mismatch.
Standing Wave Ratio (SWR) A ratio of the maximum amplitude to the minimum amplitude of a standing wave stated in current or voltage amplitudes. See also Standing Wave.
Star Quad Term given to 4-conductor microphone cables where the conductors are spiraled together, which, when connected in an "x" configuration, greatly increases common mode noise rejection.
Static Charge An electrical charge that is bound to an object. An unmoving electrical charge.
Stay Cord A component of a cable, usually of high tensile strength, used to anchor the cable ends at their points of termination and keep any pull on the cable from being transferred to the electrical conductors.
Step Insulated Process of applying insulation in two layers. Typically used in shielded networking cables such that the outer layer of insulation can be removed and remaining conductor and insulation can be terminated in a RJ-45 type connector.
Step-index Fiber An optical fiber in which the core is of a uniform refractive index with a sharp decrease in the index of refraction at the core/cladding interface.
STP Shielded Twisted Pair(s).
Strain Gauge A device for determining the amount of strain (change in dimensions) when a stress is applied.
Strand A single uninsulated wire.
Stranded Conductor A conductor composed of groups of uninsulated wires.
Strip To remove insulation from a cable or wire.
Stripping Groove The controlled thinning of the lamination between two conductors in a flat cable to allow easy hand separation. Tear feature.
Structural Return Loss Magnitude of the internal cable reflections, measured in decibels, relative to the actual cable impedance, not the system impedance. Measure of signal reflections caused by the structure of the cable without the additional reflections from any impedance mismatch between the cable and the measuring equipment. Measure of internal cable reflections using a reference impedance in the measuring equipment that is adjusted to the nominal or average impedance of the cable. See also Return Loss
Surge A temporary and relatively large increase in the voltage or current in an electric circuit or cable. Also called transient.
S-VHS Abbreviation for Super VHS. A video format in which the two parts of the video signal, the chrominance and luminance, are recorded and played back separately providing for better picture quality.  (Not to be confused with S-Video which is a transmission method).
S-Video Transmission method for video in which the two parts of the signal, the chrominance and luminance, are sent on separate transmission lines to provide better picture quality. (Not to be confused with S-VHS which is a videotape recording method).
Sweep Test Testing a characteristic of a cable or device across a range of frequencies. In cable, it usually implies return loss or structural return loss (see also).
Switch In LAN terms, this is a star topology solution for connecting various devices on the LAN. It differs from a hub in that it creates (learns) pathways from one device to another so all traffic is not seen by all devices. It can also run full duplex (simultaneous transmit and receive), buffer high speed traffic to connect to lower speed (100Mb/s to 10Mb/s), and auto sense the different speeds. See the BL-9000 series.
TCP/IP Transmission Control Protocol/Internet Protocol.
TDMA Time Division Multiple Access.
Tear Feature The controlled thinning of the lamination between two conductors in a flat cable to allow easy hand separation.
Teflon (R) DuPont Company trademark for fluorocarbon resins. (FEP - Fluorinated ethylene-propylene. A thermo-plastic material with good electrical insulating properties and chemical and heat resistance.). (TFE - Tetrafluoroethylene. A thermoplastic material with good electrical insulating properties and chemical and heat resistance.). It is not suitable where subjected to nuclear radiation and does not have good high voltage characteristics. FEP Teflon is extrudable in a manner similar to PVC and polyethylene. This means that long wire and cable lengths are available. TFE Teflon is extrudable in a hydraulic ram type process. Lengths are limited due to amount of material in the ram, thickness of the insulation, and preform size. TFE must be extruded over a silver- or nickel-coated wire. The cost of Teflon is approximately 8 to 10 times more per pound than PVC compounds.
Tefzel Fluorocopolymer thermoplastic material has excellent electrical properties, heat resistance, chemical resistance, toughness, radiation resistance, and flame resistance.
Temperature Rating The maximum temperature at which the insulating material or cable may be used in continuous operation without change of its basic properties.
Tensile Strength The pull stress required to break a bare wire.
TFE Tetrafluoroethylene. A thermoplastic material with good electrical insulating properties and chemical and heat resistance.
Thermal Rating The temperature range in which a material will perform its function without undue degradation.
Thermoplastic A material which will soften, flow, or distort appreciably when subjected to sufficient heat and pressure. Examples are polyvinyl chloride and polyethylene.
Thermosetting A material which will not soften, flow, or distort appreciably when subjected to heat and pressure. Vulcanizable. Examples are rubber and neoprene.
TIA Telecommunications Industry Association. Body which authored the TIA/EIA 568A "Commercial Building Telecommunications Wiring Standard" in conjunction with EIA.
TIA-EIA 568B "Commercial Building Telecommunications Wiring Standard" defines a generic telecommunications wiring system for commercial buildings that will support a multi-product, multi-vendor environment. It also provides direction for the design of telecommunications products for commercial enterprises.
Tight-Buffered Cable Type of cable construction whereby each glass fiber is tightly buffered by protective thermoplastic coating to diameter of 900 micrometers. Increased buffering provides ease of handling and connectorization.
Tinsel A type of electrical conductor comprised of a number of tiny threads, each thread having a fine, flat ribbon of copper or other metal closely spiraled about it. Used for small size cables requiring limpness and extra-long flex life.
Topcoated Wire Conductor produced by applying a layer of tin over a stranded bare copper conductor holding the strands together allowing easier soldering and preventing the fraying of strands.
TP-PMD Twisted Pair-Physical Medium Dependent.
Transceivers These devices are powered from a host. Legacy 10Mb/s LAN transceivers have a AUI on one side, and BNC, RJ45, or fiber connection on the other. They provide a way to listen to the network for an opportunity to transmit and not collide with other packets. See BL-50.
Transducer A device for converting one form of energy to another, such as mechanical energy to electrical energy.
Transfer Impedance For a specified cable length, transfer impedance relates to a current on one surface of a shield to the voltage drop generated by this current on the opposite surface of the shield. Transfer impedance is used to determine shield effectiveness against both ingress and egress of interfering signals. Cable shields are normally designed to reduce the transfer of interference - hence, shields with lower transfer impedance are more effective than shields with higher transfer impedance.
Transmission Line An arrangement of two or more conductors, a coaxial cable, or a waveguide used to transfer signal energy from one location to another.
Transmission Line Cable Two or more conductors placed within a dielectric material in such a way as to control the electrical characteristics.
Transmitter The electronic package that converts electrical energy to light energy in a fiber optic system. Also refers to equipment that generates RF or electrical signals for transmission through the air or space or over a transmissions line.
Triad Cable Cable with three twisted conductors.
Triaxial Cable A cable construction having a conductor, and two isolated braid shields, all insulated from each other. A coaxial cable with a second braid applied over an inner jacket and an outer jacket applied over the outer braid. Commonly used in television camera systems.
Triboelectric Noise Noise generated in a shielded cable due to variations in capacitance between the shield and conductors as the cable is flexed.
Trunk Cable In a CATV system, the transmission cable from the head end (signal pickup) to the trunk amplifier. Also called a feeder cable.
Turn-key A contractual arrangement in which one party designs and installs a system and "turns over the keys" to another party who will operate the system.
TVRO TV Receive Only.
Twin-lead A transmission line having two parallel conductors separated by insulating material. Line impedance is determined by the diameter and spacing of the conductors and the insulating material and is usually 300 ohms for television receiving antennas.
Twinax Cable Cable with two twisted conductors with established electrical properties (one pair=twinax).
Twisted Pair Two lengths of insulated conductors twisted together.  The traditional method for connecting home and many business computers to the telephone company.  Gets its name because two insulated copper wires are twisted together, both of which are needed for each connection.  In commercial environments, performance of data transmission can be improved by adding a composite tape to the wire.  This is known as shielded twisted pair.
Two pair premise wiring Refers to the two pairs of voice grade (low bandwidth) twisted pair wire installed in most homes since the 1950s.  The extra pair makes it possible for you to add another line when you need it.
UHF Ultra High Frequency. International Telecommunication Union designation for the 300-3000 MHz band of frequencies.
UL Underwriters Laboratories. A nonprofit organization which tests and verifies construction and performance of electronic parts and equipment, including wire and cable.
UM Unsoldered Mechanical Protection - Additional steel and polyethylene over inner polyethylene jacket.  Provides additional mechanical protection.
Unbalanced Line A transmission line in which voltages on the two conductors are unequal with respect to ground. A coaxial cable is a common type of unbalanced line.
Unilay A conductor with more than one layer of helically laid wires with the direction of lay and length of lay the same for all layers.
UPC (Ultra-polish Physical Contact) - It is typically used on simplex Single mode cable with SC connectors. It is used with high-end lasers or receivers where there are concerns for back reflection. A convex surface is created in the polishing to minimize reflection.
UTP Unshielded Twisted Pair(s).
V Volt (see also).
VA Volt-ampere. Measure of apparent power in a reactive circuit found by multiplying the voltage by the current.
VC/MTM Variable Constellation/Multi-Tone Modulation.
VDSL Very high bit rate Digital Subscriber Line.
Velocity of Propagation (VP) The transmission speed of electrical energy in a length of cable compared to speed of light in free space. Usually expressed as a percentage.
VHF Very High Frequency. International Telecommunication Union designation for the 30-300 MHz band of frequencies.
VHS Abbreviation for Video Home System. VHS is a trademark of Panasonic, Inc.
Video Pertaining to picture information in a television system.
VLF Very Low Frequency. International Telecommunications Union designation for the 3-30 kHz band of frequencies.
VoIP Voice over IP is a method of transmitting voice (digitally) in packets over LANs and WANs. See the BL-9000 series switches.
Volt A unit of electromotive force.
Voltage Electrical potential of electromotive force expressed in volts.
Voltage Drop The voltage developed across a component or conductor by the current flow through the resistance or impedance of the component or conductor.
Voltage Rating The highest voltage that may be continuously applied to a cable construction in conformance with standards or specifications.
Voltage Standing Wave Ratio Ratio of maximum voltage of the standing wave to the minimum voltage of the standing wave. See also Standing Wave Ratio.
VSWR Voltage Standing Wave Ratio.
VW-1 A flammability rating established by Underwriters Laboratories for wires and cables that pass a specially designed vertical flame test, formerly designed FR-1.
W Symbol for watt or wattage.
Wall Thickness The thickness of an insulation or jacket.
WAN Wide Area Network.
Watt A unit of electrical power.
Wave Form A graphical representation of a varying quantity. Usually, time is represented on the horizontal axis, and the current or voltage value is represented on the vertical axis.
Wavelength The distance between positive peaks of a signal. As the frequency increases, and waves get closer together, the wavelength decreases.
Wavelength Converters These are active devices (powered) on a LAN to change Fiber optic wavelengths generally from Multimode Fiber (62.5 micron) to Single mode Fiber (9 micron) at various speeds such as 100Mb/s or 1000Mb/s. These are generally used to gain distance using Single mode Fiber, up to 10Km or longer. See the BL-7270 series converters.
WCS Wireless Communications Service.
Wire A conductor, either bare or insulated.
Wireless Really a misnomer.  Belden makes a variety of cables needed to build the transmitting infrastructure required to support "wireless" devices.  Wireless is a technology that allows a device (phone, pager or satellite dish) to be unconnected from the transmission point of a voice, video or data signal.  The transmission infrastructure required to support such wireless devices is a wired platform of transmission towers and stations that communicate point to point and to telephone central offices.
X Symbol for reactance.
XLPE Crosslinked polyethylene is a thermoset and is crosslinked by radiation, thermally, or by moisture. XLPE offers a wide range of operating temperatures, excellent deformation, abrasion, and flame resistance. XLPE can be formulated with halogenated or non-halogenated flame retardant packages. Some grades are also rated XHHW-2 which offers excellent wet electrical properties.
XLR A multi-pin audio connector (typically 3 pins) used in microphone, line level and snake cable audio connections.
XPE-PVC Expanded Polyethylene-Polyvinyl Chloride.  Fire retardant.
Z Symbol for impedance