A - Common abbreviation for ampere (see AMPERE).
A/D (analog/digital) converter - A circuit device that converts analog signals to digital signals.
AAAC - All-aluminum alloy conductor. A special high-strength aluminum alloy.
AAR - American Association of Railroads.
AB switch - A cable switch capable of switching one cable to one of two branch cables, A or B.
Abrasion resistance - Ability to resist surface wear.
Absorption - Physical phenomenon that attenuates light traveling in fibers by converting it into heat, thereby raising the fiber’s temperature. Absorption results from impurities and defects in the glass structure.
AC - 1. Alternating current. 2. A UL cable type (armored cable) with flexible metal tape armor.
ACAR - Aluminum conductor, aluminum-reinforced cable. Used in overhead transmission and distribution.
Accelerated aging - A test that duplicates long time environmental conditions in a relatively short time.
Accelerated life test - A test in which a cable is subjected to extreme conditions to determine the life of a cable.
Acceptance test - Made to demonstrate the degree of compliance with specified requirements.
Access group - In LAN technology, all stations have identical rights to make use of computer, network or data PABX resources.
Access line - The connection between a subscriber’s facility and a public network-either a PDN, public switched network or public telephone network. Also, see LOCAL LINE.
Access method - 1. In IBM environments, a host program that manages the movement of data between the main storage and an input/output device of a computer system; BUAM, TCAM, VTAM are common data communications access methods. 2. In LAN technology, a means to allow stations to gain access to - to make use of - the network’s transmission medium; classified as shared access, which is further divided into explicit access or contended access on discrete access method.
Access unit - In the IBM token-ring network, a wiring concentrator.
ACCR - Aluminum conductor, composite reinforced aerial cable. Contains a ceramic strength member to reduce sag at high temperatures (up to 210°C).
ACR (attenuation to crosstalk ratio) - The relationship between a signal’s attenuation and near-end crosstalk (NEXT) levels expressed in decibels. ACR=usable bandwidth.
ACRF - Attenuation to crosstalk ratio far-end. Communications cable specification. See ELFEXT.
ACSR - Aluminum conductor, steel reinforced. A bare composite of aluminum and steel wires, usually aluminum around steel.
ACSR/AW - Aluminum conductor, steel reinforced using aluminum clad steel wire.
ACSR/AZ - Aluminum conductor, steel reinforced using aluminum coated steel wire.
ACSR/GA - Aluminum conductor, steel reinforced using Class A zinc-coated steel wire.
ACSR/GB - Aluminum conductor, steel reinforced using Class B zinc-coated steel wire.
ACSR/GC - Aluminum conductor, steel reinforced, using Class C zinc-coated steel wire.
ACSS - Aluminum conductor steel supported. This transmission line has fully annealed aluminum for better sag and high-temperature performance than ACSR.
Active converter - A device that converts one communication signaling standard to another (e.g., 10BASE-T to RS-232). Active converters require separate AC power sources.
Active device - Any electronic device that is supplied activating power, normally from an external source. An amplifier is a typical active device.
Adapter - A device that enables different sizes or types of plugs to mate with one another, provides for the rearrangement of leads, allows large cables with numerous wires to fan out into smaller groups of wires, or makes interconnections between cables. In fiber optics, it joins two connectors of the same (or different) types.
Adaptive equalizer - An equalizer that adjusts to meet varying line conditions; most operate automatically.
Address - The digital location of a terminal, a peripheral device, a node, or any other unit or component in a network, or process control system.
Adhesive-bonded - Cables bonded by adding an adhesive coating to the surface of the cable components, then joining and curing the adhesive to form a cable. See BONDED CABLE.
Administration subsystem - The part of a premises distribution system that includes the distribution hardware and components for adding or rearranging circuits. These components include cross-connects, interconnects and their associated patch cords and plugs.
Admittance - A measure of how easily alternating current flows in a circuit. Admittance is the reciprocal of impedance. It is expressed in mhos.
ADP - Automatic data processing.
ADPCM (adaptive differential pulse code modulation) - An encoding technique standardized by the CCITT that allows an analog voice conversation to be carried within a 32 kbps digital channel. Three or four bits are used to describe each sample, which represents the difference between two adjacent samples. Sampling is done 8,000 times per second.
ADU - Asynchronous data unit.
AEIC - Association of Edison Illuminating Companies. Electric energy industry association.
AERIAL CABLE - A cable suspended in the air on poles or other overhead structure.
AES (advanced encryption standard) - A type of cryptographic algorithm used to protect sensitive (unclassified) information. Usually seen in conjunction with wireless applications.
AF - Audio frequency.
AFCI - Arc fault circuit interrupter. A protective device that detects arcing and breaks the circuit to protect the load when arcing is detected.
AGC - Automatic gain control. A feedback circuit that automatically adjusts the system gain.
Aging - The irreversible change of material properties after exposure to an environment for an interval of time.
AIA - Aluminum interlocked armor. A type of cable sheath consisting of interlocked pieces of aluminum armor.
Air core cable - A cable in which the interstices in the cable core are not filled with a moisture barrier.
Air spaced coax - A coaxial cable in which air is basically the dielectric material. The conductor may be centered by means of a spirally wound synthetic filament, beads or braided filaments. This construction is also referred to as an air dielectric.
Aircraft wire - An electrical wire primarily designed for the extreme conditions (temperature, altitude, solvents, fuels, etc.) of airborne equipment.
AIT (advanced intelligent tape) - A type (format) of recording tape.
AL - Aluminum.
Alarming - The ability of CCTV equipment to respond to an input signal, normally a simple contact closure. The response varies depending on equipment type.
Alloy - A substance having metallic properties and being composed of an elemental metal and one or more chemical elements.
ALPETH - Telecommunications cable employing a corrugated aluminum shield and an outer polyethylene jacket.
ALS - Aluminum sheathed. A type of cable consisting of insulated conductors enclosed in a continuous, closely fitting aluminum tube. Listed type in the Canadian Electric Code.
Alternating current - Electric current that periodically reverses direction. Alternating current is generally abbreviated AC.
AM (amplitude modulation) - A method of adding information to an electronic signal where the height (amplitude) of the wave is changed to convey the added information.
Ambient temperature - The temperature of a cable group when there is no load on any cable of the group or on the duct bank containing the group.
Ambient - Conditions existing at a test operation location prior to energizing of equipment (e.g., ambient temperature).
AMI (alternate mark inversion) - A T-1 line code.
Ampacity - The current a device can carry within specified temperature limitations in a specified environment dependent upon a) temperature rating; b) power loss; and c) heat dissipation.
Ampere - A standard unit of current. Designated as the amount of current that occurs when one volt of EMF is applied across one ohm of resistance. An ampere of current is produced by one coulomb of charge passing a point in one second.
Ampere-turn - The product of amperes times the number of turns in a coil.
Amplifier - A device used to boost the strength of an electronic signal.
Amplitude distortion - An unwanted change in signal amplitude, usually caused by nonlinear elements in the communications path.
Amplitude modulation (AM) - A method of adding information to an electronic signal where the amplitude of the wave is changed to convey the added information.
Amplitude - The maximum value of a varying wave form.
Analog loopback - Technique for testing transmission equipment and devices. It isolates faults to the analog signal receiving or transmitting circuitry, where a device, such as a modem, echoes back a received (test) signal that is then compared with the original signal.
Analog - Not digital. A continuously varying waveform.
Angle of view - The angular range that can be focused within the image size. Small focal lengths give a wide angle of view, and large focal lengths give a narrow field of view.
ANI (automatic number identification) - Provides the telephone number of an incoming call for various purposes.
Anneal - To soften and relieve strains in any solid material, such as metal or glass, by heating to just below its melting point and then slowly cooling it. This also generally lowers the tensile strength of the material while improving its flex life.
Annealed wire - See SOFT WIRE.
Annular ring - An 8 mm (5/16 in.) wide black band printed at 2.5 m (8.2 ft.) intervals on standard Ethernet coaxial cable to identify locations at which transceivers may be connected.
Annular conductor - A number of wires stranded in reversed concentric layers around a core.
Annunciator wire - Usually single solid copper, sometimes twisted pair or triplexed for open wiring of bell circuits and other low-voltage systems.
ANSI (American National Standards Institute) - A not-for-profit organization that publishes nationally recognized standards.
Antenna lead-in wire - Not coaxial; parallel twin lead construction, plastic jacketed with fixed 300-ohm impedance for connecting a remote antenna to a receiver.
Antenna rotor cable - Multiconductor flat or round cable used to supply power to a motorized antenna and control wires for changing direction of rotation.
Antioxidant - Retards or prevents degradation of materials exposed to oxygen (air).
Aperture - The opening of a lens that controls the amount of light reaching the surface of the pickup device. The size of the aperture is controlled by the iris adjustment. By increasing the f-stop number (f1.4, f1.8, f2.8, etc.) less light is permitted to pass to the pickup device.
API (application programming interface) - Defines the methods by which other software applications can access and/or control a given system.
Apparent power - The product of the voltage and amperage (VA) in a system. Wiring must be sized to handle the apparent power, and utilities charge extra for loads that require large amounts of reactive power. For this reason, large industrial loads are often power factor corrected using large capacitors to prevent drawing the reactive power needed from the utility distribution system, instead drawing from the capacitors and presenting a less reactive load to the grid.
APPN (advanced peer-to-peer networking) - A System/46 feature that provides distributed processing through a set of services based on Node Type 2.1 network node and Logical Unit 6.2. These services include connectivity, directory, route selection, session activation and data transport and provide for distributed, dynamic node resource updates and intermediate, pass-through node capabilities.
Approved - 1. Acceptable to the authority having legal enforcement. 2. Per OSHA: a product that has been tested to standards and found suitable for general application, subject to limitations outlined in the nationally recognized testing lab’s listing.
Aramid yarn - Strength elements that provide tensile strength, support and additional protection for fiber bundles. Kevlar is a brand name of aramid fiber.
Arc resistance - The ability of a material to resist the action of a high-voltage electrical arc, usually stated in terms of the time required to render the material electrically conductive.
Architecture - The manner in which a system (such as a network or a computer) or program is structured. See also CLOSED ARCHITECTURE, DISTRIBUTED ARCHITECTURE and OPEN ARCHITECTURE.
Arcnet (Attached Resource Computer Network) - The Datapoint 2.5 Mbps local area network that was one of the first local area networks.
Armature - 1. Rotating machinery: the member in which alternating voltage is generated. 2. Electromagnet: the member which is moved by magnetic force.
Armor - Mechanical protector for cables; usually a helical winding of metal tape, formed so that each convolution locks mechanically upon the previous one (interlocked armor); may be a formed metal tube or a helical wrap of wires.
Armor-X - Southwire’s trademark for CCW aluminum armor.
Array connector - A connector that aligns and protects the 12 fibers from a ribbon fiber cable. A fanout array design can be used to connect ribbon fiber cables to non-ribbon cables.
Arrhenius plot - A statistical method used to predict time-to-failure, based on a device’s performance at different temperatures. One method for generating this plot is given in IEEE Standard 101.
AS/400 - Application Systems, IBM’s midrange computer system that was originally designed to operate on twinax cable, may now also be implemented on unshielded twisted pair with the use of twinax baluns.
ASCII (American National Standard Code for Information Interchange) - A seven bit plus parity code established by the American National Standards Institute to achieve compatibility among data services and consisting of 96 displayed upper and lower case characters and 32 nondisplayed control codes.
ASCII Terminal - A terminal that uses ASCII; usually synonymous with asynchronous terminal and with dumb terminal.
ASIC - An IC designed for specific applications, typically a gate array or a full custom chip.
ASIS (American Society of Industrial Security) - A professional organization for the security industry.
Askarel - Synthetic insulating oil that is nonflammable but very toxic. It has been replaced by silicone oils.
ASME - The American Society of Mechanical Engineering, a not-for-profit professional organization.
ASP - Telecommunications cable employing a corrugated aluminum shield (A), corrugated steel shield (S) and an outer polyethylene (P) jacket. Considered rodent-resistant and used primarily in underground applications.
Aspect ratio - The ratio of the picture frame width to the picture frame height in standard TV systems. It is four units horizontal and over three units vertical.
Aspherical lens - A lens designed with a nonspherical shape that refracts the light passing through it to either lower the lens aperture, so it passes more light or decrease barrel distortion on wide angle lenses.
ASTM (American Society for Testing and Materials) - A group writing standards for testing materials and specifications for materials.
ASTM - American Society for Testing and Materials. An organization that sets standards on various material tests for industry.
ASU (automatic switch unit) - Provides automatic switching from one coaxial cable or network component to a redundant cable or network component in response to loss of signal on the primary cable or component.
ASYNC - Asynchronous.
Asynchronous terminal - A terminal that uses asynchronous transmission, usually synonymous with ASCII terminal and with dumb terminal.
Asynchronous - Transmission in which each information character is individually synchronized, usually by means of start and stop elements. Also called start-stop transmission.
ATA (analog terminal adapter) - A device that converts an analog terminal, like a phone,to one that works on an ISDN line or Ethernet. (Analog to IP phone device is one example.)
ATDM (asynchronous time-division multiplexing) - A TDM that multiplexes asynchronous signalsby over-sampling; also infrequently used to mean a concentrator.
ATM (asynchronous transfer mode) - A connection-type transmission mode carrying information organized into blocks (header plus information field); it is asynchronous in the sense that recurrence of blocks depends on the required or instantaneous bit rate. Statistical and deterministic values have been proposed that correspond respectively to the packet and circuit values defined for information transfer mode.
Attenuation constant - A rating for a cable or other transmitting medium, which is the relative rate of amplitude decrease of voltage or current in the direction of travel. It is measured in decibels per unit length of cable.
Attenuation - The decrease in magnitude of a wave as it travels through any transmitting medium, such as a cable or circuitry. Attenuation is measured as a ratio or as the logarithm of a ratio (decibel).
Audio frequency - That range of frequencies lying within the range of human hearing: approximately 20 to 20,000 Hz.
Audio - A term used to describe sounds within the range of human hearing. Also used to describe devices that are designed to operate within this range.
AUI (Attachment Unit Interface) - The interface between the Ethernet/IEEE 802.3 controller and the baseband transceiver or broadband modem.
Auto white balance - A feature on color camera that constantly monitors the light and adjusts its color to maintain white areas.
Automatic frequency control (AFC) - An electronic circuit used whereby the frequency of an oscillator is automatically maintained within specified limits.
Automatic gain control (AGC) - An electronic circuit where the gain of a signal is automatically adjusted as a function of its input or other specified parameter.
Automatic iris lens - A lens in which the aperture automatically opens or closes to maintain proper light levels on the faceplate of the camera pickup device.
Automatic level control (ALC) - A feature on auto iris lenses (also known as the peak/average control). Adjusting this control allows the auto iris circuitry to either take bright spots more into consideration (peak), bringing out detail in bright areas, or less into consideration (average) bringing out detail in shadows.
Auto-terminating - A feature where the equipment (e.g., monitor) automatically selects the correct termination depending on whether the video output BNC is connected.
AVD (alternate voice data) - Telephone lines that have been electronically treated to handle both voice and data signals. Typically used on leased overseas circuits to save money.
AWG (American Wire Gauge) - A standard measurement in the determination of the physical size (diameter) of a conductor determined by its circular mil area. The gauge varies inversely with the actual wire diameter. The larger the gauge number, the smaller the wire.
AWM - Appliance Wiring Material. A UL 758 designation for a type of wire.