FOA Guide


Communications Cabling Glossary

The terms here are include more terms and acronyms than are mentioned in the actual pages but are terms which have been used over the history of the industry. For fiber optic terms, use the fiber glossary.

A, B, C, D, E, F, G, H, I, J, K, L, M, N, O, P, Q, R, S, T, U, V, W

Absorption: That portion of fiber optic attenuation resulting of conversion of optical power to heat.
ACR: attenuation to crosstalk ratio, a measure of how much more signal than noise exists in the link, by comparing the attenuated signal from one pair at the receiver to the crosstalk induced in the same pair.
Adapters: a type of balun that physically allows one connector to mate to another.
ADO: Auxiliary Disconnect Outlet
Alien Crosstalk: Crosstalk from a pair in one cable to the same pair in another adjacent cable.
American wire gage (AWG): an American system of defining the size of copper wire.
Analog: An electrical signal that carries information in a continuously varying format.
ATM: Asynchronous Transfer Mode
Attenuation: the reduction of signal strength over distance.
Attenuator: A device that reduces signal power in a fiber optic link by inducing loss.
AUI: Attachment Unit Interface, Ethernet tap on coax
Average power: The average over time of a modulated signal.
Backbone: cable that connects communications closets, entrance facilities and buildings. (Cabling Subsystem 1 in new TIA nomenclature)
Balanced transmission: sending signals of opposite polarity on each wire in a pair to maximize bandwidth and minimize interference. Used with all UTP cable.
Balun: a device that adapts one cabling type to another, including physical layout, impedance and connecting balanced to unbalanced cables.
Bandwidth: the frequency spectrum required or provided by communications networks.
BAUD RATE: Rate of signal transmission (bps) Bits per Second
Baud: for phone modems, it refers to the data rate, but in networks, it is the actual modulation rate which may not be the same as the data rate if encoding schemes are used.
BBS: Backbone System / Riser System
BD: Building Distributor
BDN: Building Distribution Network
Bend radius: minimum radius a cable can be bent without permanent damage.
BER: Bit Error Rate
Bit: An electrical or optical pulse that carries information, a single piece of digital information, a 1 or 0.
BIT: Binary Digit
Bit-error rate (BER): The fraction of data bits transmitted that are received in error.
BIX: Proprietary premises cross-connect system from Northern Telecom.
Block: devices used for interconnection of cables.
BNC: Bayonet CXC coax connectors
Bonding: a permanent electrical connection.
Bridge: a device that connects two or more sets of telephone wires.
Bus: a network where all computers are connected by a single (usually coax) cable. Bus architecture can also be implemented with a hub and star configuration.
BYTE: Eight or sixteen Bit Binary word
Cable tray: a channel system used to hold and support communications cables.
Cable: One or more conductors or fibers enclosed in protective coverings.
Capacitance: the ability of a conductor to store charge
Category-Rated unshielded twisted pair (UTP) cables: Four twisted pair UTP cable rated for frequency performance
Category 3: the UTP cable specified for signals up to 16 MHz, commonly used for telephones. (ISO/IEC Class C)
Category 4: the UTP cable specified for signals up to 20 MHz, obsolete.
Category 5/5E: the UTP cable specified for signals up to 100 MHz,  commonly used for all LANs. (ISO/IEC Class D)
Category 6/6A: the UTP cable specified for signals up to 500 MHz,  commonly used for > gigabit LANs. (ISO/IEC Class E)
Category 7: Erroneous nomenclature for  ISO/IEC Class F STP cable, not part of TIA standards in US
CATV: community antenna television, usually delivered by coax cable or HFC(hybrid fiber-coax) networks.
CBC: Communications Building Cable
CCITT: Consultants Committee for International Telephone and Telegraph
CCTV: closed circuit television, commonly used for security.
CD: Campus Distributor
CDDI: Copper Distribution Data Interface
CEMA: Canadian Electrical Manufacturers Association
Certification Tester: Tests cabling per cabling standards for length, attenuation and crosstalk.
CFC: Communication Flat Cable
Client: the computer that operates in a network using programs and data stored in a server.
CM: Communications Cables
CMG: Communications Cable General Rated
CMP: Communications Cable Plenum Rated
CMR: Communications Cable Riser Rated
CMX: Communications Cable Residential Rated
COAX, CXC : Coaxial Cable
Coax: a type of cable that uses a central conductor, insulation, outer conductor/shield and jacket, used for high frequency communications like CCTV or CATV.
Conduit: special pipe used to carry cables.  May be metal or plastic, solid or flexible.
Connector: the attachment on the end of a cable that allows interconnection to other cables.
COSP: Customer Owned Outside Plant
CP: Consolidation Point
CPE: Customer Premises Equipment
CPI: Component Premises Interface
Crimper: a tool used to install insulation-displacement plugs (IDC) on UTP cable or crimp-style connectors on coax cable.
Crossed pair: a pair of wires in a UTP cable that have  two pairs cross-connected in error.
CSA: Canadian Standards Association
CSMA/CD: carrier sensing multiple access / collision detection, the protocol of Ethernet and other networks using bus or star architecture, that controls access to the LAN.
Current loop: transmission using variable current to carry information, like a simple analog telephone.
Decibel (dB): A unit of measurement of optical power which indicates relative power on a logarithmic scale, sometimes called dBr. dB=10 log ( power ratio)
dBm:  Electrical: decibels in reference to Milliwatts , 0dBm = 1  mw base measurement
dBm: Optical: optical  power referenced to 1 milliwatt.
DC: Direct Current
DD: Distribution Device
Delay skew: the maximum difference of propagation time in all pairs of a cable.
Dial tone: the tone heard in a phone when the receiver is picked up, indicating the line is available for dialing.
Dielectric: an insulator, used to protect copper wires in cable.
Digital: signals where the information is in the form of digital bits - 1s and 0s.
Dispersion: The temporal spreading of a pulse in an optical waveguide. May be caused by modal or chromatic effects.
DIW: "D" Inside Wire
DMARC: Demarcation Point
DS0: Digital System Level "0"  , 64 KB/S,
DS1: Digital System Level "1"  , 1.544 MB/S
DS2: Digital System Level "2"  , 6.312 MB/S
DS3: Digital System Level "3"  , 44.736 MB/S
DTE: Data Terminal Equipment
DTMF: dual tone multifrequency, or tone dialing used on modern phones, where discrete tones indicate numbers.
DVO: Data Voice Outlet
EIA/TIA 568 standard: a voluntary interoperability standard developed by vendors to insure interoperability of equipment used on network cabling. The international equivalent standard is ISO/IEC 11801.
EIA/TIA: Electronics Industry Association/Telecommunications Industry Association, a vendor-based group that writes voluntary interoperability standards for communications and electronics.
EL-FEXT: Equal Level Far End Crosstalk, crosstalk ar the far end with signals of equal level being transmitted.
EMI: Electromagnetic Interference
ESD: Electrostatic Discharge
Ethernet: A network standard widely used for computer networks. Many standards exist for Ethernet over various speeds and types of media.
10 BASE 2: 10 MB/S Ethernet  on Thinnet Cable
10 BASE 5: 10 MB/S Ethernet  on Thicknet Cable
10 BASE F: 1O MB/S Ethernet  on Fiber Optic cable
10 BASE T: 10 MB/S Ethernet  Cat. 3 or better Twisted Pair Cable
100 BASE T: 100 MB/S Fast Ethernet on Cat. 5
1000 BASE LX: Gigabit Ethernet on optical fiber at 1300 nm
1000 BASE SX: Gigabit Ethernet  on optical fiber at 850 nm
1000 BASE T: Gigabit Ethernet on Cat 5e UTP
10GBASE-T: 10 Gigabit Ethernet on Cat 6A UTP
10GBASE-CX4: 10 Gigabit Ethernet on coax
10GBASE-S: 10 Gigabit Ethernet on MM at 850 nm w/VCSELs
10GBASE-LX4: 10 Gigabit Ethernet on MM or SM using WDM
10GBASE-L: 10 Gigabit Ethernet on  SM at 1310 nm for 10 km
10GBASE-LRM: 10 Gigabit Ethernet on  MM at 1310 nm w/FP lasers
10GBASE-E: 10 Gigabit Ethernet on SM at 1550 nm for 40 km
More Ethernet standards at higher speeds.
F Series Conn.: Threaded RG59 CXC Connector
FCC: Federal Communications Commission, oversees all communications issues in the USA.
FD: Floor Distributor
FDM: Frequency Division Multiplexing
Firestop: restore a fire rated partition to its fire rating after penetration with cabling,
Fishtape: semi-flexible rod used to retrieve cables or pull line.
FLAT: Flat Cable and Under-carpet cable
FMPR: Fiber Optic Multi Port Repeater
Ground loop: the flow of current caused by unequal ground potentials.
Ground: a connection between a circuit or equipment and the earth.
HC: Horizontal Cross-Connect
HDS: Horizontal Distribution System
HDSL: High Bit Rate Digital Subscriber Line
Headend: the main distribution point in a CATV system.
HFC: Hybrid fiber coax CATV network
HIPPI: High Performance Parallel Interface
Horizontal crossconnect: connection of horizontal wiring to other equipment or cabling.
Horizontal: cable that runs from a work area outlet to the communications closet. (Cabling Subsystem 2 in new TIA nomenclature)
Host: large computer used with terminals, usually a mainframe.
Hub: a switch used to connect computers in a star network.
HYBRID: Mixed Media Conductor cables. In fiber optics, refers to cable with both singlemode and multimode fibers.
Hz: Frequency, Cycles per second
IBDN: Integrated Building Distribution Network. NT Cabling System, Now owned by CDT for today !
IC: Intermediate Cross-connect
ICEA: Insulated Cable Engineers Association
ICEC: Insulated Cable Engineering Association
ICS: The IBM Cabling System
IDC: Insulation displacement connection, connecting wires by inserting or crimping cable into metal contacts that cut through the insulation, making contact with the wires.
IDC: Insulation Displacement Connector
IDF: Intermediate Distribution Frame
IEC: International Electrotechnical Committee, oversees international communications standards.
IEEE: Institute of Electrical and Electronics Engineers, professional society that oversees network standards.
Impedance matching devices: a type of balun that matches impedance between two cables.
Impedance: the AC resistance
Intermediate cross connect: connection point in the backbone cable between the main cross connect and the telecommunications closet
Internet: a worldwide network of computers that allows communications between computers.
IRL: Inter Repeater Link
ISDN: Integrated Services Digital Network
ISO: International Standards Organization, oversees international standards.
Jacket: the outer protective covering of a cable.
J-hook: a hook shaped like the letter J used to suspend cables.
Jumper cable: A short cable with connectors on both ends used for interconnecting other cables or testing.
Key system: a simple multiline phone system that allows each user to select from several lines.
km: kilometer
LAN: local area network, a group of computers and peripherals set up to communicate with each other.
LC: Small fiber optic connector with 1.25 mm ferrule
Local loop: the interconnection of telephone central offices in a small region.
Loop resistance: measurement of the resistance of both wires in a pair measured from one end with the other end shorted.
Loss budget: The amount of power lost in the link. Often used in terms of the maximum amount of loss that can be tolerated by a given link.
MAC: Media Access Control
Main cross connect: the connection point between building entrance, backbone and equipment cables. (Connection Point A in new TIA nomenclature)
Mainfame: large computer used to store and process massive amounts of data.
MAN: Metropolitan Area Network
Margin: The additional amount of loss that can be tolerated in a link.
MAU : Media Attachment Unit
MB/S: Mega Bits Per Second
MC: Main Cross-Connect
MDF: Main Distribution Frame
Mesh grip (aka Kellums grip): a grip made of wire mesh that grips the jacket of a cable for pulling.
Messenger cable: the aerial cable used to attach communications cable that has no strength member of its own.
MHz    Megahertz
MMJ: Modified Modular Jack
MMP: Modified Modular Plug
Modal dispersion: The temporal spreading of a pulse in an optical waveguide caused by  modal effects.
MODEM: Modulator / Demodulator, typically a converter from one media/protocol to another
Modular 8: the proper name for the 8 pin connector used in EIA/TIA 568 standard, commonly called the RJ-45.
Modular jack: a female connector for wall or panel installation, mates with modular plugs.
Modular plug: a standard connector used with wire, with 4 to 10 contacts, to mate cables with modular jacks.
MP: Multi Purpose Cables
MSAU: Multi-Station Access Unit
N Series Conn.: Threaded Thicknet CXC Connector
NA: Numerical Aperture, a measure of the angular acceptance of an optical fiber.
NCTA    National Cable TV Association
NEC: National Electrical Code, written by NFPA, sets standards for fire protection for construction.
NECA: National Electrical Contractors Association
NEMA: National Electrical Manufacturers Associations
Network interface (NI): the demarcation point where the public network connects to a private (commercial or residential) network.
Network: A system of cables, hardware and equipment used for communications.
NEXT: near end crosstalk, measure of interference between pairs in UTP cable.
NFPA: National Fire Protection Association, which writes the NEC.
NIC: network interface card, used to interface computers to networks.
NII: National Information Infrastructure
NIST: National Institute of Standards and Technology, establishes primary standards in the USA.
NMS: Network Management System
NOS, network operating system: the software that allows computers on a network to share data and program files.
NT: Northern Telecom
NTT: Nippon Telephone & Telecommunications
NVP, Nominal velocity of propagation : speed of an electrical signal in a cable, expressed relative to the speed of light.
NVP: Nominal Velocity of Propagation
OFN: Optical fiber non-conductive cable
OFC: Optical fiber conductive cable
OFNG or OFCG: optical fiber general purpose cable
OFNR or OFCR: optical fiber riser rated cable for runs between floors
OFNP or OFCP: optical fiber plenum-rated cable for use in air handling areas (plenums)
OFN-LS: Low smoke density optical fiber cable
Ohm    Standard unit of electrical resistance
OLAN: Optical LAN
OPM: Optical Power Meter
OSHA    Occupational Safety & Health Administration
OSI: Open Systems Interconnect
Passive Optical LAN (POL): Premises network based on passive optical network (PON) used for fiber to the home (FTTH).
Patch panel: a cross-connection using jacks and patchcords to interconnect cables.
PBX or PABX: Private Branch Exchange or Private Automatic branch Exchange
PCC: Premises Communications Cable
PCI    Peripheral Component Interconnect
PCM: Pulse Coded Modulation
PDL: power over data line, POE for single pair Ethernet.
PDS: Premises Distribution System
PIC: Plastic Insulated Conductor
Pigtail: A short length of fiber attached to a fiber optic component such as a laser or coupler.
PIN: PIN Photo Diode
Plenum: the air carrying portion of a heating or air conditioning system that can be used for running communications cables. Also a type of cable used in plenums, specially rated by the NEC.
PNI    Premises Network Interface
POL: passive optical LAN using FTTH PON technology
POTS: plain old telephone service.
Power over Ethernet (POE): Using data cables to carry power for connected devices, IEEE 802.3af and IEEE 802.3at.
Power Sum NEXT: Near end crosstalk tested with all pairs but one energized to find the total amount of crosstalk caused by simultaneous use of all pairs for communication.
PTSS: Passive Transmission Sub System
Pulse dialing: old style phone dialing that works by making and breaking the current loop a number of times to indicate the number dialled.
Punch down tool: tool used to connect wire to IDC connections in punch down blocks.
Punch-down block: a connection block incorporating insulation displacement connections for interconnecting copper wires with a special insertion tool.
110 block: Punchdown block from AT&T 110 Cross Connect System
66 block: Punchdown block from  AT&T66 Cross Connect System
BIX: Northern Telecom proprietary In-building Cross Connect System
Krone: Krone proprietary Cross Connect System
PVC: Polyvinyl Chloride
QCBIX1A: 25 pr. punchdown block, 5 pr. grouping
QCBIX1A4: 25 pr. punchdown block, 4 pr. grouping
QMBIX10A: Bix Mounting Frame
QRBIX19A: Distribution ring
QSBIX20A: Field designation strip
QTBIX16A: Punchdown tool
QUAD: Four Conductor Cable
REA:    Rural Electrification Association, Now RUS: Rural Utilities Services, US government agency assisting the development of power and communication in rural areas
Repeater, regenerator: A device that receives a signal and regenerates it for retransmission, used in long links.
Return loss: reflection from an impedance mismatch in a copper cable.
Reversed pair: a pair of wires in a UTP cable that have the two wires cross-connected in error.
RFI: Radio Frequency Interference
RG    Residential Gateway
Ring (as in "TIP and RING"):  one conductor in a phone line, connected to the Ring of the contact on  old-fashioned phone plugs.
Ring: a network where computers are connected in series to form a ring. Each computer in turn has an opportunity to use the network.
RJ11: 6 Position Modular Jack/Plug
RJ-45: a modular 8 pin connector with USOC pin configuration, referring to a specific telephone application, but usually referring to the connector used in EIA/TIA 568 standard.
SC: Fiber optic connector with 2.5 mm ferrule in plastic snap-in body
SCTE    Society of Cable & Telecommunications Engineers
ScTP: screened twisted pair cable, UTP cable with a outer shield under the jacket to prevent interference.
Server: the center of a network where programs and data are stored.
Shorted pair: a pair of wires in a UTP cable that are electrically connected in error.
Single pair Ethernet: a standard that allows operation of Ethernet over a single pair cable, intended for industrial applications.
SNR: Signal To Noise Ratio
Split pair: a pair of wires in a UTP cable that have the two wires of two different pairs cross-connected in error.
SRL, Structural Return Loss: reflections in a copper cable caused by defects.
ST: Bayonet mount fiber optic connector with 2.5 mm ferrule
Star: a network where all the computers are connected to a central hub or server.
STP: shielded twisted pair cable, where each pair has a metallic shield to prevent interference.
Structured cabling: a method of installing cable per industry standards to allow interoperability among vendors and upgrades.
Subscriber loop: connection of the end-user to the local central office telephone switch.
T1: Transmission Level 1 ,  first level of multiplexing, 1.554 MB/S, (Bell Standard)
T568A: 4 pr. EIA/TIA Modular Plug Wiring Scheme ISDN
T568B: 4 pr. EIA/TIA Modular Plug Wiring Scheme, AT&T
Take off: reading drawings of a layout to get cable plant layout.
TC: Telecommunications Closet
TDM: Time Division Multiplexing
TDR: Time Domain Reflectometer
TELCO: Telephone Company (Bell, MCI, ETC)
Telecommunications room (formerly closet): location inside a building for interconnection of backbone and horizontal cables. (Connection Point C in new TIA nomenclature)
Telegraph: earliest form of long-distance communications, using coded letters.
Telephone switch: a device that connects telephones together when signalled by dialing.
Telephone: a voice instrument for communications.
Termination: Preparation of the end of a fiber to allow connection to another fiber or an active device, sometimes also called "connectorization".
TIA: Telecommunications Industries Association
Time domain reflectometer (TDR): a testing device used for copper cable that operates like radar to find length, shorts or opens, and impedance mismatches.
Tip (as in "TIP and RING"): one conductor in a phone line, connected to the Tip of the old-fashioned phone plug.
TO: Telecommunications Outlet / Connector
TOC    Telecommunications Outlet Connector
Token Ring: a ring architecture LAN developed by IBM. 4 MB/s and 16 MB/s versions are used.
Tone dialing: used on modern phones, where discrete tones indicate numbers.
Topology: the architecture or layout of a network, eg. bus, ring, star.
TP: Transition Point
TSB: TIA Technical Service Bulletin
UL: Underwriters Laboratories (USA)
ULC: Underwriters Laboratories Canada
UNI    Universal Network Interface
USOC: Uniform Service Order Code, a UTP wiring scheme that allows 6 pin plugs to be used in 8 pin jacks for telephone use.
UTP: unshielded twisted pair cable, comprised of four pairs of conductors carefully manufacturer to preserve frequency characteristics.
Verification tester: Tests cabling using network signals.
Visual fault locator: A device that couples visible light into the fiber to allow visual tracing and testing of continuity. Some are bright enough to allow finding breaks in fiber through the cable jacket.
WAN: Wide Area Network
Watts: A linear measure of optical power, usually expressed in milliwatts (mW), microwatts (*W) or nanowatts (nW).
Wire mapping: confirming the proper connections of all four pairs.
Wireless: sending communications over radio waves.
Work area outlet: the outlet at the end of the horizontal cabling where equipment is connected with a patchcord. (Connection Point D in new TIA nomenclature)
Work area: the location of the equipment connected to horizontal cabling. Sometimes called the telecom outlet (TO) or desktop.
Working margin: The difference (in dB) between the power budget and the loss budget (i.e. the excess power margin).
Z, Zo: Impedance Symbol
ZSW: "Z" Station Wire or Quad Cable (same as QUAD)

Premises Cabling Website Contents

Each page will open in a new window.

Overview of Premises Cabling and Standards  
UTP CablesPower Over Ethernet.
UTP Terminations, (Tutorial) UTP Termination
UTP Installation VHO  66 Block, 110 Block, Jacks, Plugs  
UTP Testing,  UTP Wiremapping  
Coax Cable  VHO Coax Termination  
Fiber Optics in Premises Cabling
Design, New T-568-C Nomenclature
Premises Cabling Installation
See the "Fiber Optic Technology and Standards" Section below for information on networks, etc.
FOA Lectures on Premises Cabling and videos about cable preparation, termination, splicing and testing on FOA videos


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