B&S - Brown and Sharpe wire gauge; same as AWG.
B8ZS (Binary Eight Zero Suppression) - A method of converting eight consecutive zero bits into a recognizable, intentionally bipolar violation. The violation is converted back into eight zero bits at the receiving end. Equipment at both ends of the span must be compatible with B8ZS for proper operation, also called Binary Eight Zero Substitution.
Back focal distance - The distance from the rear most portion of the lens to the image plane.
Back light compensation (BLC) - A feature on newer CCD cameras that electronically compensates for high-background lighting to give detail that would normally be silhouetted.
Backbone - 1. In packet switched networks, the major transmission path for a PDN. 2. The trunk media of a multimedia LAN separated into sections by bridges, gateways or routers. 3. PDS terminology for that part of the distribution system, including both wire and fiber cables, which is often called riser or house distribution. The backbone does not include the interconnection cables that connect ISN equipment, such as packet controllers and concentrators, to cross-connects or interconnects.
Backbone drop - A network drop that is connected directly to the backbone segment. Backbone network - The network whose primary function is to forward network data grams between the other networks in the extended LAN.
Backbone network - The network whose primary function is to forward network data grams between The other networks in The extended LAN.
Backbone segment - The Ethernet segment whose primary function is to forward data grams between the other segments in the Ethernet in a single Ethernet LAN, See BRANCH SEGMENT.
Backbone subsystem - The part of a premises distribution system that includes the main cable route and the facilities for supporting the cable. The riser subsystem usually extends from an equipment room (often in a building’s basement) to the upper floors in a multistory building or along the same floor in a single-story building. It is terminated on a cross-connect in a riser closet, at the network interface or on the distribution components of the campus subsystem.
Backfill - The materials placed to fill an excavation, such as sand backfill in a trench.
Balanced circuit - A circuit so arranged that the impressed voltages on each conductor of the pair are equal in magnitude but opposite in polarity with respect to ground.
Balanced line - A cable having two identical conductors with the same electromagnetic characteristics in relation to other conductors and to ground.
Ballast - A device designed to stabilize current flow.
Balun (BALanced/UNbalanced) - A device that converts the impedance of one interface to the impedance of a second interface (usually coax to UTP).
Band Marking - A continuous circumferential band applied to a conductor at regular intervals for identification.
Bandwidth - The width of a communications channel, measured as frequency (in cycles per second or hertz). A channel’s bandwidth is a major factor in determining how much information it can carry.
Bare conductor - A conductor having no insulation or jacket.
Barrel connector - A female connector for connecting two sections of coaxial cable.
Barrel-packed - Method of coiling wire into a drum for shipment.
BAS - Building automation systems.
Baseband LAN - A local area network employing baseband signaling.
Baseband modem - A modem that does not modulate the signal before transmission thereby transmits the signal in its native form. Baseband signaling is the transmission of either digital or analog signals at their original frequencies.
Baseband network - A type of network that carries a single channel of communications signals.
Baseband system - A data transmission system in which information is encoded, multiplexed and transmitted without modulation of a carrier.
Baseband transmission - Transmission method used for short distances (less than 10 miles). It uses a bandwidth whose lowest frequency is zero (DC level) for transmission of raw (carrier less) binary data. The transmission medium carries only one signal at a time.
Baseband - A signaling technique in which the signal is transmitted in its original form and not changed by modulation (e.g., CCTV video X).
Battery backup unit - An optional unit within an ISN packet controller that consists of three batteries connected in series. When AC power fails, the battery backup unit delivers 144 volts DC to the power supplies on each shelf of the packet controller.
Battery backup - A battery that provides power when the main AC power fails.
Baud - The number of signal (or state) changes in a carrier per second; also referred to as baud rate. The maximum baud rate of a modem is limited by the bandwidth of the phone line.
BCD (binary coded decimal) - Group of binary digits representing decimal numbers, with each number allocated four binary digits. This system is widely used in telecommunications computer projects.
Bedding - A layer of material applied to a cable immediately below the armoring.
Beldfoil - Belden trademark for highly effective electrostatic shield using reinforced metallic foil.
Belt - Layers of insulation on a conductor, or layers of jacket on a cable.
Belted-type cable - Multiple conductor cable having a layer of insulation over the assembled insulated conductors.
Bend loss - A form of increased attenuation caused by (a) having an optical fiber curved around a restrictive radius of curvature or (b) micro bends caused by minute distortions in the fiber imposed by externally induced perturbations.
Bend radius - 1. The radius of curvature that a fiber can bend without breaking or causing excessive loss in fiber cable. 2. In copper cable, the minimum radius that a cable can be bent without the possibility of causing structural or electrical damage to the cable.
BEP - Building entrance protection.
BER (bit error rate) - The ratio of received bits that are in error, relative to a specific amount of bits received; usually expressed as a number referenced to a power of 10.
BERT (bit error rate tester) - A network diagnostic instrument used to troubleshoot LANs.
BICSI - Building Industry Consulting Service International.
BIL - Basic impulse level. The crest value of a lightning impulse voltage of a specified wave shape that a high-voltage cable or termination is required to withstand under specified conditions.
Bimetallic wire - A wire formed of two different metals joined together (not alloyed). It can include wire with a steel core, plated or coated wire.
Binary - 1. A half-duplex, character-oriented synchronous data communications protocol originated by IBM in 1964. 2. Digital system with two states: 1 and 0.
Binary encoded - A signal consisting of two states such as on or off, high or low level, one or zero, or presence or absence of a signal.
Binder - A tape or thread used for holding assembled cable components in place.
Binding post - A device for clamping or holding electrical conductors in a rigid position.
Bipolar transmission - Method of sending binary data in which negative and positive states alternate; used in digital transmission facilities such as DDS and T1, sometimes known as polar transmission.
Bipolar violation - Two or more successive pulses having the same polarity in a bit stream.
Birdcage - The undesired unwinding of a stranded cable.
BISDN (broadband ISDN) - A form of the integrated services digital network (ISDN) that will carry digital transmission at rates equal to or greater than the T1 rate (1.544 megabits per second). BISDN standards packetize information (e.g., voice, data and video) into fixed-length cells for transmission over synchronous optical networks.
Bit stream - A digital signal or series of pulses.
Bit - Contraction of binary digit; fundamental unit of information expressed in digital form as the choice between only two states, for example, 0 or 1, or high or low, or on or off.
Bits per second (bps) - The number of bits of data transmitted by a modem through a phone line in one second. To get the bps rate of a modem, multiply the number of signal changes per second (baud rate) by the number of bits of information carried by each change.
Black level - The level of the video signal that corresponds to the maximum limits of the black areas of the picture.
Blanking - The process of cutting off the electron beam in a camera pickup device or picture tube during the retrace period. It is a signal that is composed of recurrent pulses at line and field frequencies. It is intended primarily to make the retrace on a pickup device or picture tube invisible.
Blooming - The halation and defocusing effect that occurs around the bright areas of the picture (highlight) whenever there is an increase in the brightness intensity.
BNC - Common connector for coax. BNC is said to be short for Bayonet Neill-Concelman.
Bonded cable - Cable consisting of pre-insulated conductors or multi-conductor components lay in parallel and bonded into a flat cable.
Bonded construction - An insulation construction in which the glass braid and nylon jacket are bonded together.
Bonding - The connecting together of all building and equipment electrical grounds to eliminate differences in electrical ground potential.
Booster - A device inserted into a line (or cable) to increase the voltage. Boosting generators are also used to raise the level of a DC line. Transformers are usually employed to boost AC voltages. The term booster is also applied to antenna preamplifiers.
Boot - 1. Protective coating over a cable, wire or connector in addition to the normal jacketing or insulation. 2. A form placed around the wire termination of a multi-contact connector to contain the liquid potting compound before it hardens.
Border light candle - Same as stage cable but more than two conductors. Type SO cable is often used.
Bore hole cable - Power and/or communications cable suspended down a vertically drilled hole to equipment underground.
BPS or BIS (bits per second) - The number of bits passing a point per second. A measure of the speed of transmission of digital information; used to describe the information transfer rate on a circuit.
Braid angle - The smaller of the angles formed by the shielding strand and the axis of the cable being shielded.
Braid carrier - A spool or bobbin on a braiding machine that holds one group of strands or filaments consisting of a specific number of ends. The carrier revolves during braiding operations.
Braid ends - The number of strands used to make up one carrier. The strands are wound side by side on the carrier bobbin and lie parallel in the finished braid.
Braid - Textile or metallic filaments interwoven to form a tubular structure which may be applied over one or more wires or flattened to form a strap (see shield).
Braiding machine - Machine used to apply braids to wire and cable and to produce braided sleeving and braids for tying or lacing purposes. Braiding machines are identified by the number of carriers.
Branch joint - A cable joint used for connecting one or more cables to a main cable.
Branch network - Any network that is linked by a bridge to the backbone network or to another branch network in an extended LAN. Every network except the backbone network is a branch network.
Branch segment - Any segment that is linked by a repeater to the backbone segment in a single Ethernet LAN. Branch segments carry data grams to and from stations on the branch segment to the backbone segment.
Branch - An intermediate cable distribution line in a broadband coaxial network that either deeds or is fed from a main trunk, same as a feeder.
Brazing - The joining of ends of two wires, rods, or groups of wires with nonferrous filler metal at temperatures above 800°F (427°C).
Breakdown (puncture) - A disruptive discharge through insulation.
Breakdown voltage - The voltage at which the insulation between two conductors breaks down and becomes conductive.
Breaking strength - The maximum load that a conductor attains when tested in tension to rupture.
Breakout - The point at which a conductor or group of conductors breaks out from a multi-conductor cable to complete circuits at various points along the main cable.
BRI (basic rate interface) - The ISDN term that refers to the basic ISDN interface of 2B +D. Operating at 144 kbps, BRI provides two B (bearer) channels at6 4 Kbps and a D (data) channel at 16 kbps.
Bridge - A circuit that measures by balancing four impedances through which the same current flows: Wheatstone-Resistance, Kelvin-Low resistance, Schering-Capacitance, dissipation factor, dielectric constant, Wien-Capacitance, and dissipation factor.
Bridged Tap - The multiple appearances of the same cable pair at several distribution points.
Bridging - A term indicating that a high-impedance video line is paralleled, usually through a switch, to a source of video.
British standard wire gauge - A modification of the Birmingham Wire Gauge and the legal standard of Great Britain for all wires; also known as Standard Wire Gauge (SWG), New British Standard (NBS), English Legal Standard and Imperial Wire Guide.
Broadband LAN - A LAN that uses FDM (frequency division multiplexing) to divide a single physical channel into a number of smaller independent frequency channels. The different channels created by FDM can be used to transfer different forms of information; voice, data, and video.
Broadcast - The act of sending a signal from one station on a LAN to all other stations, all of which are capable of receiving that signal.
BSC (binary synchronous communications) - A byte- or character-oriented IBM communications protocol that has become an industry standard. It uses a defined set of control characters and sequences for synchronized transmission of binary-coded data between stations in a data communications system.
BSL (basic switching impulse insulation level) - The crest value of a switching impulse voltage of a specified wave shape in which a high-voltage cable termination is required to withstand under specified conditions.
Buffer tube - A loose, crush-resistant polymer tube applied over optical fibers to provide mechanical protection.
Buffer - A protective coating in intimate contact with an optical fiber.
Building entrance area - The area inside a building where cables enter and are connected to riser cables and where electrical protection is provided. The network interface, as well as the protectors and other distribution components for the campus subsystem, may be located here.
Building wire - Commercial wires used in the building trades because they are independently tested and listed in the National Electric Code, such as types RHH, RHW, THW and THHN wire.
Buna - A synthetic rubber insulation of styrene butadiene; was known as GR-S, now known as SBR (Styrene Butadiene Rubber).
Bunch strand - A conductor arrangement in which all individual wires are twisted in the same direction without regard for geometrical arrangement.
Buncher - A machine that twists wires together in a random arrangement.
Buoyant cable - Originally military type MIL-C-2401 with built-in floatation ability. Many power and communications applications using numerous types and sizes have been developed using buoyancy.
Buried cable - A cable installed directly in the earth without use of underground conduit, also called “direct burial cable.”
Bus and tag (serpentine) cable assembly (IBM) - This assembly used as an interface from IBM 360/370/380 mainframe computers.
Bus network - A one-cable LAN, in which all workstations are connected to a single cable. On a bus network, all workstations hear all transmission on the cable. Each workstation then selects those transmissions addressed to it.
Bus - A network topology that functions like a signal line that is shared by a number of nodes.
Bus-bar wire - Un-insulated tinned copper wire used as a common lead.
Bushing - A mechanical device used as a lining for an opening to prevent abrasion to wire and cable.
Butt splice - A splice wherein two wire ends butt against each other, or against a stop, in the center of a splice.
Butt wrap - Tape wrapped around an object or conductor in an edge-to-edge condition.
Butyl rubber - Synthetic rubber formerly used for electrical insulating purposes.
BX - A common type of armored building wire rated 600 volts.
Byte - A collection of bits operated upon as a unit. Most bytes are eight bits long, and most character sets use one byte per character. The capacity of storage devices is frequently given in bytes or in K bytes (K meaning 1,024 bytes).