(We wish to thank Unicom for their contributions.)
Cable – An insulated conductor or group of individually insulated conductors in twisted or parallel configuration.
Cable Assembly – A completed cable and its associated hardware ready to install.
Cabling* – A combination of cables, wire, cords and connecting hardware used in the telecommunications infrastructure.
Cabling Factor – Used in the formula for calculating the diameter of an unshielded, unjacketed cable. D=Kd where D is the cable diameter, K is the factor and d is the diameter of one insulated conductor.
Campus Backbone* – Cabling between buildings that share telecommunications facilities.
Capacitance – The ratio of the electrostatic charge on a conductor to the potential difference between the conductors required to maintain that charge.
Carrier Sense Multiple Access with Collision Detection (CSMA/CD)* – The LAN access method used in Ethernet. When a device wants to gain access to the network, it checks to see if the network is quiet (senses the carrier). If it is not, it waits a random amount of time before retrying. If the network is quiet and two devices access the line at exactly the same time, their signals collide. When the collision is detected, they both back off and each wait a random amount of time before retrying.
Channel* – The end-to-end transmission path connecting any two points at which application specific equipment is connected.
Characteristic Impedance – The impedance that, when connected to the output terminals of a transmission line of any length, makes the line appear infinitely long. The ration of voltage to current at every point along the transmission line on which there are no standing waves.
Cladding* – In fiber-optic cabling, a layer of glass that surrounds the inner core and reflects light back into the core.
Class I Repeater* – Class I Repeaters operate by translating line signal on the incoming port to a digital signal. This allows the translation between different types of Fast Ethernet like 100Base-TX and 100Base-FX. Class I repeaters introduce delays when performing this conversion so that only one repeater can be put in a single Fast Ethernet LAN segment.
Class II Repeater* – Class II Repeaters immediately repeat the signal on the incoming port to all the ports on the repeater. This quick movement of the data introduces Very little delay across the repeater, thus two class II repeaters are allowed per Fast Ethernet segment.
Coaxial Cable (Coax)* – Formerly common in Ethernet networks, coax comes in various types with different transmission characteristics. It is copper-based, with an inner conductor surrounded by an outer conductor, with insulation between the two, insulation around the outer conductor, and a jacket. Coax is less flexible than twisted pair cable, but more resistant to EMI and physical breakage.
Collision* – Concurrent Ethernet transmissions from two or more devices on the same segment. A collision is sensed by the transmitting station as an over-voltage condition causing the station to retransmit after waiting a random amount of time.
Collision Domain* – Single CSMA/CD LAN segment.
Color Code – A system for circuit identification through use of solid colors and contrasting tracers.
Concentric Stranding – A central wire surrounded by one or more layer of helically wound strands in a fixed geometric arrangement.
Concentricity – In a wire or cable, the measurement of the location of the center of the conductor with respect to the geometric center of the surrounding insulation.
Conductivity – The capability of a material to carry electrical current – usually expressed as a percentage of copper conductivity (copper being 100%).
Conductor – An uninsulated wire suitable for carrying electric current.
Conduit – A tube or trough in which insulated wires and cables are run.
Connector – A device used to physically and electrically connect two or more conductors.
Continuity Check – A test to determine whether electrical current flows continuously throughout the length of a single wire or individual wires in a cable.
Copolymer – A compound resulting from the polymerization of two different monomers.
Copperweld – The trade name of Flexo Wire Division (Copperweld Steel Corp.) for their copper-clad steel conductors.
Core – In cables, a component or assembly of components over which additional components (shield, sheath, etc.) are applied.
Coverage – The percent of completeness with which a metal braid covers the underlying surface .
Cross-connect* – A facility enabling the termination of cables as well as their interconnection or cross-connection with other cabling or equipment.
Crosstalk* – The unwanted introduction of signals from one channel or pair to another.
C.S.A. – Abbreviation for Canadian Standards Association, a non-profit, independent organization which operates a listing service for electrical and electronic materials and equipment. The Canadian counterpart of the Underwriters Laboratories.
Cut-Through Resistance – The ability of a material to withstand mechanical pressure, usually a sharp edge or small radius, without separation
Data Communications Equipment (DCE)* – Traditional data communications terminology for the equipment that enables a DTE to communicate over a telephone line or data circuit. The DCE establishes, maintains, and terminates a connection as well as performing the conversions necessary for communications.
Data Terminal Equipment (DTE)* – Traditional data communications terminology for a device receiving and/or originating data on a network. Typically, a computer or patch panel.
DCE (Data Circuit-terminating equipment)* – The designation given to equipment such as modems and multiplexers by the Electronic Industry of America (EIA). Differs from DTE (Data Terminal Equipment) in that it transmits data on pin 3 and receives data on pin 2.
Decibel (dB)* – A logarithmic comparison of power levels defined as ten times the base ten log of the ratio of input power to output power. One tenth of a bel.
Demarcation Point* – The point inside your building (or on the campus premises) at which the phone company (or other service provider) is no longer responsible for network cabling or service.
Dielectric – Any insulating material between two conductors which permits electrostatic attraction and repulsion to take place across it.
Dielectric Constant (E) – The radio of the capacitance of a condenser with dielectric between the electrodes to the capacitance when air is between the electrodes. Also called Permittivity and Specific Inductive Capacity.
Dielectric Strength – The voltage which an insulation can withstand before breakdown occurs. Usually expressed as a voltage gradient (such as volts per mil).
Digital Line* – A data or voice network interconnectivity medium that supports digital signaling.
Direct Current Resistance (B.C.R.) – The resistance offered by any circuit to the flow of direct current
Dissipation Factor – The tangent of a loss angle of the insulating material. (Also referred to as loss tangent, tan §, and approximate power factor.)
Drain Wire – In a cable, the uninsulated wire laid over the component or components and used as a ground connection.
DSL (Digital Subscriber Line)* – A method for moving data over regular phone lines. A DSL circuit is much faster than a regular phone connection and uses the same copper premises wires used for regular phone service. A DSL circuit must be configured to connect two specific locations, similar to a leased line. DSL is now a popular alternative to ISDN and leased lines, being faster than ISDN and less costly than traditional leased lines.
D-Sub connector* – AUI cable use 15-pin D-sub connectors. “D” refers to the shape of the connector shell. Also called miniature D, DB-15, or DIX connectors.
DTE (Data Terminal Equipment)* – The RS232-C Standard referring to equipment that transmits and/or receives data on a network. This standard typically applies to terminals, PCs, and printers.
D-Type* – The standard connector used for RS232-C, RS423 and RS422 communication. It is most commonly used in 9, 15, and 25-pin configurations.
Duplex* – A technique allowing bi-directional, simultaneous transmission along a channel. Generally referred to as full duplex.
Eccentricity – Like concentricity, a measure of the center of a conductor’s location with respect to the circular cross section of the insulation. Expressed as a percentage of displacement of one circle within the other.
EIA* – Electronic Industries Association
EIA 568* – A commercial building wiring standard for voice and data communications developed in 1989 by EIA.
ELFEXT (Equal Level Far-end Crosstalk)* – Crosstalk measured at the opposite end from which the disturbing signal is transmitted, normalized by the attenuation contribution of the cable or cabling.
Elongation – The fractional increase in length of a material stressed in tension.
EMI (Electromagnetic Interference)* – Energy generated by outside sources, such as lighting systems and electric motors, which is received by copper data/voice cable and interferes with transmission.
End – In braiding, the number of essentially parallel wires or threads on a carrier.
Ethernet* – The most common layer-two protocol used in LANs. Ethernet is a 10 Mbps CSMA/CD standard originally developed by Xerox to run on thick coaxial cabling. It has evolved and now runs primarily on twisted pair cabling.