C - Symbol designation for capacitance, bias supply and centigrade.
C-conditioning - A type of line conditioning that controls attenuation, distortion and delay distortion to within specific limits.
C-Connector - A bayonet-locking connector for coax; the C refers to Carl Concelman.
C mount/CS mount - CCTV lenses are available in two different lens mounts. C mount lenses have a flange back distance of 17.5 mm vs. 12.5 mm for CS mount lenses. Many of today’s cameras can accept either type of lens, but it is important to make sure the camera and lens are compatible and set up properly. C mount lenses can be used on CS mount cameras by utilizing a 5 mm adapter or adjusting the camera for C mount lenses. Because of the short back focal distance, CS mount lenses can only be used on CS mount cameras. Your picture will be out of focus if you use a CS mount lens on a C mount camera.
CCD (charged coupled device) - A CCD chip that is the pickup device on a camera, performing a similar function as a camera tube.
Cabinet - A physical enclosure for rack-mount equipment; standard cabinets have 1 3/4 in. zvertical spacing between mounting holes and 19 in. wide horizontal spacing between mounting rails.
Cable - A cable may be a small number of large conductors or a large number of small conductors cabled together, usually color coded and with a protective overall jacket.
Cable assembly - 1. A cable assembly is a cable with plugs or connectors on each end for a specific purpose. It may be formed in various configurations. 2. See PATCH CORD.
Cable belted - A multi-conductor cable having a layer of insulation over the assembled insulated conductors.
Cable-based LAN - A shared-medium LAN that uses a cable for its transmission medium.
Cable clamp - A device used to give mechanical support to the wire bundle or cable at the rear of a plug or receptacle.
Cable clamp adapter - A mechanical adapter that attaches to the rear of a plug or receptacle to allow the attachment of a cable clamp.
Cable concentrator - A device that converts several individual cables to a larger single cable without loss of signal information.
Cable core - The portion of an insulated cable lying under a protective covering.
Cable core binder - A wrapping of tapes or cords around the conductors of a multiple-conductor cable used to hold them together.
Cable filler - The material used in multiple-conductor cables to occupy the interstices formed by the assembly of the insulated conductors, thus forming a cable core.
Cable joint - A completely insulated splice, or group of insulated splices, contained within a single protective covering or housing. In some designs, the insulating material may also serve as the protective covering.
Cable loss - The amount of RF (radio frequency) signal attenuated by coaxial cable transmission. The cable attenuation is a function of frequency, media type and cable distance. For coaxial cable, higher frequencies have greater loss than lower frequencies and follow a logarithmic function. Cable losses are usually calculated for the highest frequency carried on the cable.
Cable Pressurized - A cable having a pressurized fluid (gas or oil) as part of the insulation; nitrogen and oil are the most common fluids.
Cable sheath - The protective covering applied to cables.
Cable spacer - An aerial distribution cable made of covered conductors held in place by insulated spacers; designed for wooded areas.
Cable support - A device to mount a cable on a supporting member.
Cable & cabling system - In LAN technology, the medium used to interconnect stations; often called the premises network.
Cable tilt - The increase in cable attenuation as the frequency increases.
Cable, tray - A multi-conductor cable having a nonmetallic jacket designed for use in cable trays per the National Electrical Code.
Cabling - The method by which a group of insulated conductors is mechanically assembled (or twisted together).
CAD - Computer aided design.
CAM - Computer-aided manufacture.
Campus subsystem - The part of a premises distribution system that includes the cable, in rebuilding distribution facilities, protectors and connectors that enable communications among multiple buildings on a premises.
Candlepower - The unit measure of an incident light.
Capacitance - The ability of a dielectric material between conductors to store electricity when a difference of potential exists between the conductors. The unit of measurement is the farad, which is the capacitance value that will store a charge of one coulomb when a 1-volt potential difference exists between the conductors. One farad is the capacitance value that will permit one ampere of current, when the voltage across the capacitor changes at the rate of one volt, per second.
Capacitance direct - The capacitance measured from one conductor to another conductor through a single insulating layer.
Capacitance mutual - The capacitance between two conductors (typically of a pair) with all other conductors, including shield, short circuited to ground.
Capacitance unbalanced - An inequality of capacitance between the wires of two or more pairs that result in a transfer of unwanted signal from one pair to others.
Capacitance unbalanced-to-ground - An inequality of capacitance between the ground capacitance of the conductors of a pair, which results in a pickup of external noise energy, usually from power transmission lines.
Capacitive coupling - Electrical interaction between two conductors caused by the potential difference between them.
Capacitive reactance - The opposition to alternating current due to the capacitance of a capacitor, cable or circuit. It is measured in ohms and is equal to 1/6.28 fC where f is the frequency in Hz and C is the capacitance in farads.
Capacitor - Two conducting surfaces separated by a dielectric material. The capacitance is determined by the area of the surface, types of dielectric and spacing between the conducting surfaces.
Capillary action - Movement of a liquid along a small interstice due to surface tension.
Carbon block - A device for protecting cable from being hit by lightning strikes in electrical storms. The carbon block consists of two electrodes spaced, so any voltage above the design level is arced from line to ground. Carbon block protectors are used commonly in both local customer offices and central offices. They are effective, but can be destroyed if high voltage is directly applied-as in a direct strike by lightning. See also GAS DISCHARGE TUBE.
Carrier - (1) An AC electrical signal that is used to carry information. (2) The woven element of a braid consisting of one or more ends (strands) which creates the interlaced effect. (3) A spindle, spool, tube, or bobbin (on a braiding machine) containing yarn or wire, employed as a braid.
Carrier band - A band of continuous frequencies that can be modulated with a signal.
Cascade - The number of amplifiers connected in series on a broadband trunk cable.
Cathode – (1) The negative electrode through that current leaves a nonmetallic conductor, such as an electrolytic cell. (2) The positive pole of a storage battery. (3) In vacuum tubes, the electrode that emits electrons.
Cathode-ray tube - The electronic tube that has a screen upon which a beam of electrons from the cathode can be made to create images; for example, the television picture tube.
Cathodic protection - Reduction or prevention of corrosion by making the metal to be protected the cathode in a direct current circuit.
CATV (community antenna television) - Refers to the use of a coaxial cable to transmit television or other signals to subscribers from a single head end location.
CATV cable - General term for all cables used for community antenna TV service and feeders, distribution and house drops.
CAU (controlled access unit) - IBM’s 8230 is a wiring concentrator that supports up to 80 devices on a ring. The base unit, when used alone or in conjunction with up to four lobe attachment modules (LAMs), functions as a copper repeater or optical fiber converter at either four or sixteen megabits per second.
CB (Citizens band) - One type of two-way radio communication.
CBN (common bonding network) - A grounding term used in TIA standards.
CCIA - Computer and Communications Industry Association.
CCITT - A United Nations-sponsored organization, in Geneva, Switzerland, devoted to establishing worldwide communications standards. In English, it is known as the International Consultative Committee for Telephone and Telegraph.
CCS (copper clad steel) - Used in CATV, RG-59, 11 and 6 cables.
CCTV (closed-circuit television) - Video security cameras.
CCU (communications control unit) - In IBM 3270 systems, a communications computer, often a minicomputer, associated with a host mainframe computer. It may perform communications protocol, control message handling, code conversion, and error control and applications functions.
CCW - Continuously corrugated and welded. A type of cable armor.
CD (collision detection) - The ability of a transmitting node to detect simultaneous transmission attempts on a shared medium.
CD (carrier detect) - An RS-232 control signal (on pin 8) that indicates the local modem is receiving a signal from the remote modem. Also called received line signal detector (RSLD) and data carrier detect (DCD).
CDMA (code division multiple access) - A wireless (cellular) telephony.
CDR - Call detail recording.
Cellular polyethylene - Expanded or “foam” polyethylene, consisting of individual closed cells of inert gas suspended in a polyethylene medium, resulting in a desirable reduction of dielectric constant.
Cenelec - Comite European de Normalization Electrique. European Electrical Standards Institute.
Certificate of compliance - A written statement normally generated by a quality control department that states that the product being shipped meets a particular specification.
Certified test report (CTR) - A report reflecting actual test data on the cable shipped. Tests are normally conducted by the quality control department and show that the product being shipped meets the required test specifications.
CFM (cubic feet per minute) - Usually associated with air flow and cooling systems.
CFR (Code of Federal Regulations) - The general and permanent rules published in the Federal Register by the executive departments and agencies of the federal government.
Channel – (1) A path for electrical transmission, also called a circuit facility, line, link or path. (2) A specific and discrete bandwidth allocation in the radio frequency spectrum (for example, in a broadband LAN) utilized to transmit one information signal at a time.
Channel translator - Device used in broadband LANs to increase carrier frequency, converting upstream (toward the head-end) signals into downstream signals (away from the head-end).
Characteristic impedance - A frequency dependent resistance that quantifies the complex opposition to current flow offered by a transmission line.
Charge - The cause of material bodies exerting forces on each other of repulsion or attraction. The unit of measure is the coulomb, which corresponds to a charge of 6.24 x 1,018 electrons.
Charging current - See CURRENT, CHARGING.
Chemical Stripping - Removal of insulation by chemical means.
Chlorosulfonated polyethylene (CSP) - A rubbery polymer used for insulations and jackets. Previously manufactured by E.I. DuPont under the trade name of Hypalon.
CI Cable - Circuit Integrity cable. An optional rating for UL Listed cable types that meet the two-hour fire survival requirements of UL Standard 2196, e.g., FPLP-CI.
CIC Cable - Circuit Integrity in Conduit cable. A generic term for cables that meet the two-hour fire survival requirements of UL Standard 2196 when installed in metallic conduit per UL category FHIT.
CIF (common intermediate format) - A video resolution format sometimes called compressed image format. The resolution ratings of all digital or IP cameras are given in multiples or divisions of CIF. In an image, it is true grid resolution based upon the number of pixels in horizontal rows and vertical columns.
Cigarette wrap - Tape insulation wrapped longitudinally instead of spirally over a conductor.
Circuit - A system of conducting media designed to pass an electric current.
Circuit switching - A switching technique in which an information path (i.e., circuit) between calling and called stations is established on demand for exclusive use by the connected parties until the connection is released.
Circuit tracing - Locating or identifying a specific conductive path.
Circular mil (CM) - A term universally used to define cross-sectional areas of conductors. It is an area equal to the area of a circle 1/1000 of an inch in diameter. As the number of circular mils increase, the size of a wire increases.
Cladding - The low refractive index material that surrounds the core of an optical fiber.
Clad wire - Different from coated wire, it is any metal covered with a relatively heavy coating of different metal, such as copper weld (copper over steel) or alum-o-weld (aluminum over steel). See COATED WIRE.
CLC - IBM’s abbreviation for cluster controller. The central node in a star-shaped cluster network, which governs all message traffic to and from the other nodes.
Closed architecture - An architecture that is compatible only with hardware and software from a single manufacturer. Contrast with OPEN ARCHITECTURE.
Closed cell - Foamed or cellular material with intact cell walls, usually filled with air. Generally harder, better insulating, but more expensive than open cell material.
Closet, telecommunications - An enclosed space for housing telecommunications equipment, cable terminations and cross-connects. The closet is the recognized cross-connect between the backbone and horizontal cabling.
Cluster - A collection of terminals or other devices in a single location.
CMIP (common management information protocol) - The network management standard by OSI.
CMIS (common management information services) - An OSI network management standard. CMIS services are provided by CMIP.
CMOS (complimentary-symmetry metal oxide semiconductor) - An imaging device used in some low-end cameras.
CNR - Carrier to noise ratio.
CO - Central office.
CO lines - These are the lines connecting your office to your local telephone company’s central office, which in turn connects you to the nationwide telephone system.
Coated wire - Any metal covered by a relatively thin coating of a different metal such as tin, zinc or other alloy by a dip bath and wipe process, often at high speeds in line with insulating equipment.
Coatings - Light is lost by reflection from optical surfaces that are intended to be refractors only. This loss is effectively reduced by very thin coatings on the lens surfaces. This can be seen as a blue or violet hue on the lens surface.
Coaxial cable - A cylindrical transmission line comprised of a conductor centered inside a metallic tube or shield, separated by a dielectric material and usually covered by an insulatingjacket.
Codec - An assembly comprising an encoder and a decoder in the same equipment.
Coherent source - A fiber optic light source that emits a very narrow, unidirectional beam of light of one wavelength (monochromatic).
Coil effect - The inductive effect exhibited by a spiral wrapped shield, especially above audio frequencies.
Cold bend - Generally refers to a test to determine cable or wire characteristics at low temperatures. The test specimen is cooled in a low-temperature box to a specified temperature. The wire specimen is then wound around a mandrel after which it is examined for cracks or other defects caused by bending at low temperatures.
Cold flow - Permanent deformation of the insulation due to mechanical pressure (not due to heat softening).
Cold-drawing - Reducing the cross section by pulling through a die or dies at a temperature lower than recrystallization.
Collision - Overlapping transmissions that occur when two or more nodes attempt to transmit at or about the same instant. Their interference is a collision.
Collision detection (CD) - The ability of a transmitting node to detect simultaneous transmission attempt: a shared medium.
Color burst - The portion of a composite video signal that comprises a few cycles of a sine wave of chrominance subcarrier frequency used to establish a reference for demodulating the chrominance signal.
Color code - A color system for wire or circuit identification by use of solid colors, tracers, braids, surface printing, etc.
Combination stranded conductor - A conventional concentric conductor in which the wires in the outer layer are larger in diameter than the wires in the inner layer or layers and the diameters of all wires are within plus and minus 5 percent of the nominal wire diameter for the same size non-combination stranded conductor.
Common axis cabling - In multi-conductor constructions, a twisting of all conductors about a “common axis” to result in smaller diameter constructions; Tends to result in greater susceptibility to electromagnetic and electrostatic interference.
Common carrier - A data communications utility company or a government organization that furnishes communications services to the general public and is usually regulated by local, state or federal agencies. Often PTTs provide these services outside, and the USA Telco’s inside.
Common mode noise - Noise caused by a difference in ground potential. By grounding at either end rather than both ends (usually grounded at source) one can reduce this interference.
Communications controller - A device within a host computer that allows communication with the LAN.
Communications protocol - The means used to control the orderly exchange of information between stations on a data link or on a communications network or system, also called line discipline or protocol, for short.
Communications server - An intelligent service providing communications functions. Usually, an intelligent, specially configured node on a LAN designed to enable remote communications access to, and egress from, LAN users.
Compact stranded conductor - A unidirectional or conventional concentric conductor manufactured to a specified diameter, approximately 8 to 10 percent below the nominal diameter of a non-compact conductor of the same cross-sectional area.
Composite - The line side of a concentrator or multiplexer that includes all the multiplexed data.
Composite cable - A cable containing more than one gauge size or a variety of circuit types, e.g., pairs, triples, quads, coaxial, etc.
Composite clad wire - A wire having a core of one metal with a fused outer shell of a different metal.
Composite conductor - A conductor consisting of two or more types of wire, each type of wire being plain, clad, or coated-stranded together to operate mechanically and electrically as a single conductor.
Composite video - The combined video signal that includes the picture signal, the vertical and horizontal blanking and synchronizing pulses.
Compound filled splice - Joints in which the joint housing is filled with an insulating compound that is non-fluid at normal operating temperatures.
Compressed stranded conductor - A conventional concentric conductor manufactured to a diameter not more than 3 percent below the nominal diameter of a non-compressed conductor of the same cross-sectional area.
Compression - Two types are available: data compression, which reduces the number of bits required to represent data (accomplished in many ways, including using special coding to represent strings of repeat characters or using fewer bits to represent the more frequently used characters); analog compression that reduces the bandwidth needed to transmit analog signal, also called compaction.
Compression lug or splice - A connection installed by compressing the connector onto the strand, ideally creating a cold weld.
Compromised balanced network - Circuitry in a D4 channel unit card that provides a matching interface to the customer loop to facilitate proper transmission characteristics.
Computer room - Any room or area where several multiuser computers are located.
Concentration - Collection of data at an intermediate point from several low- and medium-speed lines for transmission across one high-speed line.
Concentrator - One of the basic components of an ISN system. The concentrator accepts as many as 40 data streams from terminals and hosts, and multiplexes them for transmission through an optical fiber cable connected to the packet controller. In turn, it accepts a multiplexed data stream from the Packet Controller, divides it into multiple signals (de-multiplexes) and forwards messages to the proper devices.
Concentric lay conductor - A layer of un-insulated wires twisted around a central wire with subsequent layers spirally wrapped around the inner layers to form a single conductor.
Concentric stranding - A group of un-insulated wires twisted together and containing a center core with subsequent layers spirally wrapped around the core to form a single conductor.
Concentricity - The measurement of the location of the center of the conductor with respectto the geometric center of the circular insulation.
Conditioning - The “tuning” or addition of equipment to improve the transmission characteristics or quality of a leased voice-grade line, so it meets specifications for data transmission.
Conductance - The ability of a conductor to carry an electric charge. The real part of admittances. It is the reciprocal of resistance and is measured in mhos.
Conductivity - The ability of a material to allow electrons to flow, measured by the current per unit of voltage applied. Usually expressed as a percentage of copper conductivity (copper being 100 percent). Also, it is the reciprocal of resistivity. I t has units of mhos/meter.
Conductor - A material suitable for carrying an electric current.
- Compact round conductor - A conductor constructed with a central wire surrounded by one or more pre shaped (non-round) helically-laid wires and formed into final shape by rolling, drawing or other means.
- Concentric-lay conecctor - A conductor constructed with a central wire surrounded by one or more layers of helically-laid wires.
- Conventional concentric conductor - A conductor constructed with a central wire surrounded by one or more layers of helically-laid wires. The direction of lay is reversed in successive layers and generally with an increase in length of lay for successive layers.
- Equilay conductor - A conductor constructed with a central wire surrounded by more than one layer of helically-laid wires, all layers having a common length of lay, direction of lay being reversed in successive layers.
- Parallel core conductor - A conductor constructed with a central core of parallel-laid wires surrounded by one layer of helically-laid wires.
- Rope-lay conductor - A conductor constructed of a bunch-stranded or a concentric-stranded member or members, as a central wire, around which are laid one or more helical layers of such members.
- Unidirectional conductor - A conductor constructed with a central wire surrounded by more than one layer of helically-laid wires, all layers having a common direction of lay, with increase in length of lay for each successive layer.
- Unilay conductor - A conductor constructed with a central wire surrounded by more than one layer of helically-laid wires, all layers having a common length and direction of lay.
Conductor core - The center strand or member about which one or more layers of wires or members are laid helically to form a concentric-lay or rope-lay conductor.
Conductor shield - A conducting layer applied to make the conductor a smooth surface in intimate contact with the insulation; sometimes called Extruded Strand Shield (ESS).
Conduit - A pipe, usually metal, that runs either from floor to floor, or along a floor or ceiling, to protect cables. In the riser subsystem, when riser closets are not aligned, conduit is used to protect cable and provide the means for pulling cable from floor to floor. In a horizontal subsystem, conduit may be used between a riser closet and an information outlet in an office or other room. Conduit is also used for in-conduit campus distribution, where it is run underground between buildings and intermediate manholes and encased in concrete.
Connecting block - A flame-retardant plastic block containing metal wiring terminals (insulation displacement contacts) that establish an electrically tight connection between the cable and the cross-connect wire.
Connecting hardware - A device providing mechanical cable terminations. Connection – (1) An established data communications path. (2) The process of establishing that path. (3) A point of attachment for that path.
Connection delta - Interconnection of three electrical equipment windings in a DELTA (triangular) configuration.
Connection diagram - Indicates the location and describes the types of connectors to be used at every junction in the distribution system.
Connection wye - Interconnection of three electrical equipment windings in WYE (star) configuration.
Connector - A metallic device of suitable electric conductance and mechanical strength, used to splice the ends of two or more cable conductors, or as a terminal connector on a single conductor. Conductors are sometimes spliced without connectors by soldering, brazing or welding. Connectors usually fall into one of the following types:
- Compression or indent
Contact - The part of a connector that carries the electrical current.
Contact size - The largest size wire that can be used with the specific contact. Also, the diameter of the engagement end of the pin.
Contention - A “dispute” between two or more devices over the use of a common channel at the same time.
Continuity check - A test performed on a length of finished wire or cable to determine if an electrical current flows.
Continuous vulcanization - Simultaneous extrusion and vulcanization (cross linking) of wire insulating and jacketing materials; also referred to as CV cured.
Contrahelical - Wire strands spiraling in an opposite direction than the preceding layer within a wire or cable.
Control cable - A cable used for remote control operation of any type of electrical power equipment.
Controlled impedance cable - A package of two or more insulated conductors where impedance measurements between respective conductors are kept essentially constant throughout the entire length.
Copper-clad steel - Steel with a coating of copper welded to it before drawing as opposed to copper-plated. Synonymous with Copperweld.
Copperweld- Trademark of Copperweld Steel Co. for copper-clad steel conductor.
Copolymer - A polymer consisting of a “mixture” of two or more polymers.
Cord - A very flexible insulated cable.
Cord set - Portable cords fitted with a connector at one or both ends.
Core - (1) In cables, a component or assembly of components over which other materials are applied, such as additional components, shield, sheath or armor. (2) The light transmitting portion of an optical fiber that has a higher index of refraction than the cladding. The core is typically 50 or 62.5 microns in diameter for multimode and 8 to 9 microns for single-mode.
Corona - A discharge due to ionization of the air around a conductor due to a potential gradient exceeding a certain critical value. See PARTIAL DISCHARGE.
Corona resistance - The time that the insulation will withstand a specified level of ionizationthat does not result in the complete breakdown of the insulation.
Corrosion - The destruction of the surface of a metal by chemical reaction.
COS (Committee for Open Systems) - A group of major computer manufacturers whose intent it was to form standards of interconnection for computer systems. One result of their efforts was the 150/051 network model.
Coulomb - The derived 51 unit for quantity of electricity or electrical charge: One coulomb equals one ampere-second.
Counter EMF - The voltage opposing the applied voltage and the current in ac oil; caused by a flow of current in the coil; also known as back EMF.
Counterpoise wire - Bare copper wire used to offset the impact of lightning surges along high-voltage overhead lines and around the base of towers. Buried counterpoise wire is connected to overhead ground wires and towers. Numerous methods of application are used, dependent upon resistance of the soil at the tower base.
Coupling - The transfer of energy between two or more cables or components of a circuit.
Coupling loss - Signal losses in an optical fiber due to small differences in numerical aperture, core diameter, core concentricity and tolerances in connectors when two fibers are spliced together. Also known as splicing loss and transfer loss.
Coverage - The calculated percentage that defines the completeness with which a metal braid covers the underlying surface. The higher percentage of coverage, the greater the protection against external interference.
CPC - Customer premises communication. CPC (calling party control) - A signal from most electronic COs to indicate that the calling party has hung up. Sometimes called open loopsdisconnect. The timing on this signal ranges from 250 to 500 m/s.
CPE - Dow Chemical trademark for chlorinated polyethylene. A jacketing compound.
CPE (customer premises equipment) - A telecommunications term for voice or data equipment that resides at a customer’s premises.
CPP (cable patch panel) - A panel, half of which is used to terminate cables coming from faceplates, and half of which is used to terminate cables coming from network or host connections. The connections are joined using patch cables.
CPS (cycles per second) - This is an obsolete designation and is now called hertz (Hz). The SI unit is the hertz: one cycle per second. CPS (characters per second) - When referring to printers, a measure of the average number of characters that the printer can print in one second.
CPU (central processing unit) - Actually the heart of a computer, but often used as a synonym for computer.
CRAC - Computer room air conditioner (data center term).
CRM - Customer relationship management.
Cross-bar switches - In older PABX technology, a switch having multiple vertical paths, multiple horizontal paths and electromagnetically operated mechanical means for connecting any vertical path with any horizontal path. Modern PABXs often use an electronic version of the cross-bar switch.
Cross-connect - The apparatus in a distribution system providing for the termination of twisted pairs or optical fibers and the rearrangement and testing of circuits. In a wire cross-connect, incoming and outgoing twisted pairs terminate on separate connecting blocks, and patch cords complete the circuits. In a light wave cross-connect, incoming and outgoing fibers terminate in connectors that fit into fiber couplings and single fiber jumpers complete the circuits.
Cross-connect field - A color-coded strip identifying the type of service carried on the cables terminated on a wire cross-connect terminal block. The color code is: - Green: central office trunks - Blue: station cables - Purple: ISN equipment, multiplexing devices, PBX ports - White: house cables - Yellow: auxiliary equipment (such as an application processor) - Orange: multiplexer ports (premises light wave system only) - Gray: tie cables (between riser and apparatus and satellite closets)
Cross-connect, horizontal - See HORIZONTAL CROSS-CONNECT.
Cross-linked - Intermolecular bonds created between long-chain thermoplastic polymers bychemical or electron bombardment means. The properties of the resulting thermosetting material are usually improved.
Cross-linked polyethylene - A dielectric material used for insulating and jacketing, also referred to as “XLP” or “XLPE.”
Crosstalk - A type of interference caused by audio frequencies from one line being coupled into adjacent lines. The term is loosely used also to include coupling at higher frequencies.
CRT (cathode-ray tube) - A television-like picture tube used in terminals; CRT is commonly used as a synonym for the CRT terminal.
CRT wire - High-voltage lead wire for energizing cathode ray tubes.
CSA (Canadian Standards Association) - The Canadian Standards Association is a not-for-profit membership-based association serving business, industry, government and consumers in Canada and the global marketplace. Similar to UL in the United States.
CSA Certified - A product that has been tested and found to comply with applicable Canadian standards.
CSMA (carrier sense multiple access) - A contention technique that allows multiple stations to gain access to a single channel. A contended access method in which stations listen before transmission, send a packet and then free the line for other stations. With CSMA, although stations do not transmit until the medium is clear, collisions still occur; two alternative versions (CSMA/CA and CSMA/ CD) attempt to reduce both the number of collisions and the severity of their impact.
CSMA/CD/CA (carrier sense multiple access with collision detection) - A contention technique that allows multiple stations to successfully share a broadcast channel by avoiding contention via carrier sense and deference and managing collisions via collision detection and packet retransmission. See CSMA and COLLISION DETECTION.
CSO (composite second order) - A type of signal distortion in CATV transmission.
CSPE - A jacketing compound based on DuPont’s Chlorosulfonated polyethylene (Hypalon). Sometimes abbreviated CSP.
CSU (channel service unit) - A digital DCE unit for DDS lines; interfaces with DSU on customer’s premises.
CT (cable tray) - NEC Article 318. A cable marking indicating a single conductor cable
suitable for use in a cable tray.
CTB (composite triple beat) - A type of signal distortion in CATV transmission.
CTI - Computer telephony integration. Usually provides a screen-pop and other interaction.
Cure - To change the properties of a polymeric system into a more stable, usable condition by the use of heat, radiation or reaction with chemical additives.
Curing cycle - The time, temperature and pressure required for curing.
Curl- The degree to which a wire tends to form a circle after removal from a spool.
Current - The rate of transfer of electricity. The unit of current is the ampere, a rate of one coulomb a second.
Current alternating (AC) - An electric current that periodically reverses direction of electron flow. The number of cycles in a given unit of time (generally a second) is called the frequency of the current.
Current carrying capacity - The maximum current an insulated conductor can safely carry without exceeding its insulation and jacket temperature limitations. Same as ampacity.
Current charging - The current needed to bring the cable up to voltage; determined by the capacitance of the cable. The charging current will be 90° out of phase with the voltage.
Current density - The current per cross sectional area in units of amperes/meters2.
Current direct (DC) - Electrical current whose electrons flow in one direction only. It may be constant or pulsating as long as their movement is in the same direction.
Customer premises - Building(s) with grounds and appurtenances (belongings).
Cut-through resistance - The ability of a material to withstand mechanical pressure without damage.
CV - Continuous vulcanization. Insulation and jacketing curing process.
CWDM - Course wavelength division multiplexing.
CXR - Carrier. A continuous light wave or radio frequency that is transmitted over a cable and is modulated with a signal. The receiving terminal interprets any change in signal as information. Changes to the signal made by outside influences (noise) can cause the receiving terminal to misinterpret the information transmitted.
Cycle - The complete sequence, including reversal of the flow, of an alternating electric current.