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Network
Cabling Glossary
A B C
D E F
G H I
J K L
M N O
P Q R
S T U
V W X
Y Z
- A
- Ampere - A unit of measure of electrical current.
- AC
- see Alternating Current.
- Access Method
- The rules by which a network device gains the rights
to transmit a communication on the network. Common methods include
carrier sense multiple access with collision detection, token passing,
and demand priority.
- ACR
- see Attenuation Crosstalk Ratio.
- Alternating Current
- An electric current that cyclically reverses the
direction of flow. Frequency is the rate at which a full cycle occurs
in one second.
- ANSI
- American National Standards Institute
- Analog Signal
- An electrical signal that varies continuously without
having discrete values (as with a "digital" signal).
- ARCnet
- Attached Resource Computer Network. A relatively low
speed form of LAN data link technology (2.5 Mbps) developed by
Datapoint, in which all systems are attached to a common coaxial
cable. ARCnet uses a token-bus form of medium access control in which
a system transmits only when it has the token
- Attachment Unit Interface.
- The IEEE 802.3 standard name for the cable connecting
an Ethernet transceiver (MAU) to a networked device. An AUI cable is
equipped with a 15-pin connector that mates with a 15-pin connector on
the networked device.
- Attenuation
- The decrease in magnitude of a signal as it travels
through any transmission medium such as a cable or optical fiber.
Measured in dB per unit of length.
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- Backbone
- A cable connection between telecommunication or
wiring closets, floor distribution terminals, entrance facilities, and
equipment rooms either within or between buildings. In star networks,
the backbone cable interconnects hubs and similar devices, as opposed
to cables running between hub and station. In a bus network, the bus
cable.
- Balanced Cable, Balanced Line
- A cable having two identical conductors that carry
voltages of opposite polarities and equal magnitude with respect to
ground. The conductors are twisted to maintain balance over a
distance.
- Balun
- An impedance matching transformer that converts the
impedance of one interface to the impedance of another interface.
Generally used to connect balanced twisted pair cabling with
unbalanced coaxial cabling. The term is derived from "balanced /
unbalanced".
- Baseband
- A transmission method in which the entire bandwidth
of the transmission medium is used to transmit a single digital
signal. The signal is driven directly onto the transmission medium
without modulation of any kind. Baseband is simpler, cheaper and less
sophisticated than Broadband.
- Bandwidth
- The range of frequencies required for proper
transmission of a signal. Expressed in Hertz (cycles per second). The
higher the bandwidth, the more information that can be carried. A
continuous range starting from zero is said to be "baseband",
while a range starting substantially above zero is
"broadband".
- Baud
- The number of changes in signal per second. A given
baud rate does not necessarily transmit an equal number of bits/sec.
For example, a signal with four voltage levels may be used to transfer
two bits of information for every baud.
- Bend Loss
- A form of increased attenuation in an optical fiber
caused by an excessively small bend radius. The attenuation may be
permanent if microfractures caused by the bend continue to affect
transmission of the light signal.
- Bend Radius
- Radius of curvature that a fiber optic or metallic
cable can bend before the risk of breakage or increased attenuation
occurs.
- BICSI
- Building Industry Consulting Service International.
- Bonding
- A method used to produce good electrical contact
between metallic parts. Also refers to the grounding bars and straps
used in buildings to bond equipment to an approved ground.
- Broadband
- A transmission facility having a bandwidth sufficient
to carry multiple voice, video or data channels simultaneously. Each
channel occupies (is modulated to) a different frequency bandwidth on
the transmission medium and is demodulated to its original frequency
at the receiving end. Channels are separated by "guardbands"
(empty spaces) to ensure that each channel will not interfere with its
neighboring channels. This technique is used to provide many CATV
channels on one coaxial cable.
- Buffer
- A protective coating over a strand of optical fiber.
- Bus Topology
- 1. In general, a physical layout of network devices
in which all devices must share a common medium to transfer data, and
no two devices may transmit simultaneously. 2. With LANs, a linear
network topology in which all computers are connected to a single
cable.
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- Cable
- A group of insulated conductors enclosed within a
common jacket.
- Cable Sheath
- A covering over the conductor assembly that may
include one or more metallic members, strength members, or jackets.
- Carrier Sense Multiple Access with Collision Detect
- A network access method used by Ethernet in which a
station listens for traffic before transmitting. If two stations
transmit simultaneously, a collision is detected and both stations
wait a brief time before attempting to transmit again.
- Category 1, Cat 1
- Unshielded twisted pair used for transmission of
audio frequencies. Used as speaker wire, door bell wire, etc. Not
suitable for networking applications.
- Category 2, Cat 2
- Unshielded twisted pair used for transmission at
frequencies up to 1.5 Mhz. Used in analog telephone applications. Not
suitable for networking applications.
- Category 3, Cat 3
- Unshielded twisted pair with 100 ohm impedance and
electrical characteristics supporting transmission at frequencies up
to 16 MHz. Defined by the TIA/EIA 568-A specification.
- Category 4, Cat 4
- Unshielded twisted pair with 100 ohm impedance and
electrical characteristics supporting transmission at frequencies up
to 20 MHz. Defined by the TIA/EIA 568-A specification.
- Category 5, Cat 5
- Unshielded twisted pair with 100 ohm impedance and
electrical characteristics supporting transmission at frequencies up
to 100 MHz. Defined by the TIA/EIA 568-A specification.
- Category 5e, Cat 5e, Enhanced Cat 5, Cat 5+
- Category 5e is a new standard that will specify
transmission performance that exceeds Cat 5. Cat 5e has improved
specifications for NEXT, PSELFEXT, and Attenuation. Like Cat 5, it
consists of unshielded twisted pair with 100 ohm impedance and
electrical characteristics supporting transmission at frequencies up
to 100 MHz. To be defined in the TIA 568-A-5 update.
- Category 6, Cat 6
- Category 6 is a proposed standard that aims to
support transmission at frequencies up to 250 MHz over 100 ohm twisted
pair.
- Category 7, Cat 7
- Category 7 is a proposed standard that aims to
support transmission at frequencies up to 600 MHz over 100 ohm twisted
pair.
- CDDI
- Copper Distributed Data Interface - A version of FDDI
that uses copper wire media instead of fiber optic cable.
- Channel Insertion Loss
- For fiber optic links, the static loss of a link
between a transmitter and receiver. It includes the loss of the fiber,
connectors, and splices.
- Characteristic Impedance
- The impedance that an infinitely long transmission
line would have at its input terminal. If a transmission line is
terminated in its characteristic impedance, it will appear
(electrically) to be infinitely long, thus minimizing signal
reflections from the end of the line.
- Chirping
- Refers to the change of optical frequency of laser
diodes when the laser diode is pulsed between two different optical
power levels. Chirp broadens the laser's spectral width causing
chromatic dispersion.
- Cladding
- The material surrounding the core of a fiber optic
cable. The cladding must have a lower index of refraction than the
core in order to contain the light in the core.
- Class A
- ISO/IEC 11801 designation for twisted pair cabling
rated to 100 KHz. Used in voice and low frequency applications.
Comparable to Category 1 cabling. Not suitable for networking
applications
- Class B
- ISO/IEC 11801 designation for twisted pair cabling
rated to 1 MHz. Used in medium bit rate applications. Comparable to
Category 2 cabling. Not suitable for networking applications
- Class C
- ISO/IEC 11801 designation for twisted pair cabling
rated to 16 MHz. Used in high bit rate applications. Corresponds to
TIA/EIA Category 3 cabling.
- Class D
- ISO/IEC 11801 designation for twisted pair cabling
rated to 100 MHz. Used in very high bit rate applications. Corresponds
to TIA/EIA Category 5 cabling.
- Class E
- ISO/IEC proposal for twisted pair cabling rated to
250 MHz. Corresponds to the proposed TIA/EIA Category 6 cabling
standard.
- Closet
- An enclosed space for housing telecommunications and
networking equipment, cable terminations, and cross-connect cabling.
It contains the horizontal cross connect where the backbone cable
cross-connects with the horizontal cable.
- Conduit
- A rigid or flexible metallic or nonmetallic raceway
of circular cross section in which cables are housed for protection
and to prevent burning cable from spreading flames or smoke in the
event of a fire.
- Core
- The central region of an optical fiber through which
light is transmitted.
- Critical angle
- The angle at the interface between core and cladding
where a guided ray in the core undergoes total internal reflection.
- Cross Connect
- A facility enabling the termination of cable elements
and their interconnection, and/or cross-connection, primarily by means
of a patch cord or jumper.
- Cross Connection
- A connection scheme between cabling runs, subsystems,
and equipment using patch cords or jumpers that attach to connecting
hardware at each end.
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- D Connector
- see Subminiature D Connector
- Data Connector
- A four position connector for 150-ohm STP used
primarily with Token-Ring networks.
- Data Grade
- A term used for twisted-pair cable used in networks
to carry data signals. Data grade media has a higher frequency rating
than voice grade media used in telephone wiring.
- DCE
- Data Communications Equipment. Any equipment that
connects to Data Terminal Equipment (DTE) to allow transmission
between DTEs.
- DC Loop Resistance
- The total DC resistance of a cable. For twisted pair
cable, it includes the round trip resistance, down one wire of the
pair and back up the other wire.
- .
- Dielectric Constant
- The property of a dielectric which determines the
amount of electrostatic energy that can be stored by the material when
a given voltage is applied to it. Also called permattivity.
- Dispersion
- The phenomenon in an optical fiber whereby light
photons arrive at a distant point in different phase than they entered
the fiber. Dispersion causes receive signal distortion that ultimately
limits the bandwidth and usable length of the fiber cable. The two
major types of dispersion are 1) mode (or modal) dispersion caused by
differential optical path lengths in a multimode fiber, and 2)
material dispersion caused by differing transmission times of
different wavelengths of light in the fiber optic material.
- DIW
- Direct Inside Wire. Twisted pair wire used inside a
building, usually two or four pair AWG 26.
- Drain Wire
- An uninsulated wire in contact with a shield
throughout its length. Used to terminate the shield.
- Duct
- 1. A single enclosed raceway for wires or cable. 2.
An enclosure in which air is moved.
- Duplex
- 1. (data communications) A circuit used to transmit
signals simultaneously in both directions. 2. (general) Two
receptacles or jacks in a common housing which accepts two plugs.
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- E1/E3
- The European versions of T1 and T3. E1 runs at 2.048
Mbps and E3 runs at 34 Mbps.
- Earth
- A term for zero reference ground.
- EC
- European Community
- ECMA
- European Computer Manufacturer's Association. A
European trade organization that issues its own standards and is a
member of the ISO.
- ELFEXT
- Equal Level Far End Crosstalk
- EMI
- see Electromagnetic Interference.
- EPDM
- Ethylene-propylene-diene monomer rubber. A material
with good insulating properties.
- EPR
- Ethylene-propylene copolymer rubber. A material with
good insulating properties.
- Ethernet
- A local area network (LAN) protocol defined in the
IEEE 802.3 standard in which computers access the network through a
Carrier Sense Multiple Access / Collision Detect (CSMA/CD) protocol.
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- f
- Frequency
- Farad
- A unit of capacitance that stores one coulomb of
electrical charge when one volt of electrical pressure is applied.
- Far End Cross Talk (FEXT)
- Crosstalk that is measured on the quiet line at the
opposite end as the source of energy on the active line. FEXT is not
typically measured in cabling, with Near End Cross Talk (NEXT) being
the preferred crosstalk measurement.
- Fast Ethernet
- Ethernet standard supporting 100 Mbps operation.
- FDDI
- Fiber Distributed Data Interface. An ANSI Standard
(ANSI X3T12) for a 100 Mbps token passing network based on fiber-optic
(FDDI) and twisted-pair (CDDI) cabling.
- Fiber Optics
- The technology in which communication signals in the
form of modulated light beams are transmitted over a glass fiber
transmission medium. Fiber optic technology offers high bandwidth,
small space needs and protection from electromagnetic interference,
eavesdropping and radioactivity.
- Fifty-pin Connector
- Commonly referred to as a Telco, CHAMP, or blue
ribbon connector, this connector is used on Ethernet 10Base-T hubs as
an alternate twisted-pair segment connection method. The 50-pin
connector connects to 25-pair cables, which are frequently used in
telephone wiring systems and which typically meet Category 3
specifications.
- Fillers
- Nonconducting components cabled with the insulated
conductors or optical fibers to impart roundness, flexibility, tensile
strength, or a combination of all three.
- Floating
- Refers to a circuit that has no connection to ground.
- FOIRL
- Fiber Optic Inter-Repeater Link. An Ethernet fiber
optic connection method intended for connection of repeaters.
- Frequency
- The number of times a periodic action occurs in a
unit of time. Expressed in hertz (abbreviated Hz). One hertz equals
one cycle per second.
- Frequency Division Multiplexing (FDM)
- A technique for combining many signals on a single
circuit by dividing the available transmission bandwidth by frequency
into narrower bands, each used for a separate communication channel.
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- G
- Green
- Gbps
- Gigabits per second.
- Giga
- A prefix meaning one billion
- Gigahertz (GHz)
- One billion hertz.
- GIPOF
- Graded Index Plastic Optical Fiber
- Graded Index Fiber
- A multimode fiber optic cable design in which the
index of refraction of the core is lower toward the outside of the
core and progressively increases toward the center of the core,
thereby reducing modal dispersion of the signal.
- Ground
- A common point of zero potential such as a metal
chassis or ground rod.
- Ground Loop
- A condition where an unintended connection to ground
is made through an interfering electrical conductor.
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- Half Duplex Transmission
- Data transmission over a circuit capable of
transmitting in either direction, but not simultaneously.
- HC
- see Horizontal Cross Connect.
- Headend
- The equipment in a cable system which receives the
various program source signals, processes them, and retransmits them
to subscribers.
- Headroom
- The amount by which a cable ACR exceeds 10dB.
- Hertz
- The unit of frequency, one cycle per second
(abbreviated Hz).
- HF
- High Frequency
- Home Run
- A cable run that connects a user outlet directly with
the telecommunications or wiring closet, with no intermediate splices,
bridges, taps, or other connections.
- Horizontal Cabling, Horizontal Wiring
- The portion of the cabling system that extends from
the work area outlet to the horizontal cross connect in the
telecommunications or wiring closet.
- Horizontal Cross Connect
- A cross connect of horizontal cabling to other
cabling, e.g. horizontal, backbone, or equipment.
- Host
- Computer that offers services on a network.
- Hub
- A hardware device that contains multiple independent
but connected modules of network and internetworking equipment. Hubs
can be active (where they repeat signals set to them) or passive
(where they do not repeat but merely split signals sent through them).
Hub may also refer to a repeater, bridge, switch, router, or any
combination of these.
- HVAC
- Heating, ventilation, and air conditioning system.
- Hybrid Cable
- An assembly of two or more cables (of the same or
different types or categories) covered by one overall sheath.
- Hypalon
- A DuPont trade name for a synthetic rubber (chlorosulfonated
polyethylene) used as insulating and jacketing material for cabling.
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- I
- Symbol used to designate current.
- IDC
- Insulation Displacement Contact/Connector
- IDF
- Intermediate Distribution Frame. This is usually
located on each floor within a building. It is tied directly to the
Main Distribution Frame via cables.
- IEEE
- Institute of Electrical and Electronics Engineers. A
professional organization and standards body. The IEEE Project 802 is
the group within IEEE responsible for LAN technology standards.
- IEEE 802.1
- The IEEE standards committee defining High Level
Interfaces, Network Management, Internetworking, and other issues
common across LAN technologies.
- IEEE 802.2
- The IEEE standards committee defining Logical Link
Control (LLC).
- IEEE 802.3
- The IEEE standards committee defining Ethernet
networks.
- IEEE 802.5
- The IEEE standards committee defining Token-Ring
standards.
- Impedance
- A unit of measure, expressed in Ohms, of the total
opposition (resistance, capacitance and inductance) offered to the
flow of an alternating current.
- Impedance Match
- A condition where the impedance of a particular
circuit cable or component is the same as the impedance of the
circuit, cable, or device to which it is connected.
- Infrastructure, Telecommunications
- A collection of those telecommunications components,
excluding equipment, that together provide the basic support for the
distribution of all information within a building or campus.
- Interconnection
- A connection scheme that provides for the direct
connection of a cable to another cable or to an equipment cable
without a patch cord or jumper.
- Intermediate Cross Connect
- A cross-connect between 1st level and 2nd level
backbone cabling.
- Injection Laser Diode
- A semiconductor laser in which the lasing occurs at
the junction of n-type and p-type semiconductor materials.
- ISO
- International Standards Organization
- Isolated Ground
- A separate ground conductor which is insulated from
the equipment or building ground.
- ITU
- International Telecommunications Union. An
international organization that develops communications standards.
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- Jabber
- Term used with Ethernet to describe the act of
continuously sending data. A jabbering station is one whose circuitry
or logic has failed, and which has locked up a network channel with
its incessant transmission.
- Jack
- A female connector.
- Jacket
- The outer protective covering of a cable.
- Jitter
- The slight movement of a transmission signal in time
or phase that can introduce errors and loss of synchronization. More
jitter will be encountered with longer cables, cables with higher
attenuation, and signals at higher data rates. Also, called phase
jitter, timing distortion, or intersymbol interference.
- Jumper
- An assembly of twisted pairs without connectors used
to used to join telecommunications circuits at the cross connect.
Similar to a patch cable (which has connectors).
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- Keying
- The mechanical feature of a connector system that
guarantees correct orientation of a connection, or prevents the
connection to a jack, or to an optical fiber adapter, of the same type
intended for another purpose.
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- L
- Symbol used to designate inductance.
- LAN
- Local Area Network
- LAN Adapter
- see Network Interface Card
- Laser
- Light Amplification by Stimulated Emission of
Radiation. A device which produces light with a narrow spectral width.
Used in fiber optic communication systems, usually single mode, where
high capacity and low attenuation are required.
- Lay
- The axial distance required for one cabled conductor
or conductor strand to complete one revolution about the axis around
which it is cabled.
- Lay Direction
- The direction of the progressing spiral twist in
while looking along the axis of the cable away from the observer. The
lay direction can be either "left" or "right".
- LCL
- see Longitudinal Conversion Loss
- LCTL
- see Longitudinal Conversion Transfer Loss
- Leakage
- An undesirable passage of current over the surface of
or through a connector.
- Leased Line
- A private telephone line rented for the exclusive use
of a leasing customer, without interchange switching arrangements.
- Light Emitting Diode
- A semiconductor diode which emits incoherent light
when a current is passed through it. Used as a light source in fiber
optic transmission.
- Link
- A transmission path between two points not including
terminal equipment, work area cables, or equipment cables.
- LocalTalk
- A low-speed form of LAN data link technology, part of
Apple Computer's AppleTalk networking scheme, that uses a carrier
sense multiple access with collision avoidance (CSMA/CA) form of
medium access control. Supports transmission at 230 Kbps.
- Loopback
- A type of diagnostic test in which a transmitted
signal is returned to the sending device after passing through a data
communications link or network. This test allows the comparison of a
returned signal with the transmitted signal.
- Loss
- The portion of energy applied to a system that is
dissipated and performs no useful work.
- Lossy
- Having poor efficiency.
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- M
- Mutual Inductance
- mA
- Milliampere (one thousandth of an ampere)
- MAC
- see Medium Access Control
- Main Cross Connect
- A cross connect for first level backbone cables,
entrance cables, and equipment cables. The main cross connect is at
the top level of the premises cabling tree.
- Media
- Wire, cable, or conductors used for transmission of
signals.
- Media Filter
- An impedance matching component used in Token-Ring
networks to transform the 100 ohm impedance of UTP cabling to the 150
ohm impedance of media interface connections.
- Medium Access Control (MAC)
- A mechanism operating at the data link layer of local
area networks which manages access to the communications channel
(medium).
- Medium Dependent Interface (MDI)
- In Ethernet, the connector used to make the
mechanical and electrical interface between a transceiver and a media
segment. An 8-pin RJ-45 connector is the MDI for the 10Base-T,
100Base-TX, 100Base-T2, 100Base-T4, and 1000Base-T media systems.
- Medium Independent Interface (MII)
- Used with 100 Mbps Ethernet systems to attach MAC
level hardware to a variety of physical media systems. Similar to the
AUI interface used with 10 Mbps Ethernet systems. An MII provides a
40-pin connection to outboard transceivers (also called PHY devices).
- Mega
- Prefix meaning one million.
- Megahertz (MHz)
- One million hertz.
- MIC
- Medium Interface Connector. Duplex fiber optic
connector used with Fiber Distributed Data Interface (FDDI) networks.
- Mixing Segment
- Ethernet term used in IEEE 802.3 standards to
describe a segment that may have more than two MDI connections.
- MMF
- set Multimode Fiber
- Modal Dispersion
- Dispersion that results from the different transit
lengths of different propagating modes in a multimode optical fiber.
- Mode
- A single electromagnetic wave traveling in an optical
fiber.
- Mode Field Diameter
- The diameter of optical energy in a single mode
fiber. Because the mode-field diameter is larger than the core
diameter, it replaces core diameter as a practical parameter.
- MSAU
- Multi-station Access Unit. Device used to
interconnect lobe cables from stations on a Token-Ring network.
- MT-RJ
- Proposal for a new duplex fiber optic connector
standard from AMP/Siecor.
- Multimode Fiber
- A fiber optic cable which supports the propagation of
multiple modes. Multimode fiber may have a typical core diameter of 50
to 100 µm with a refractive index that is graded or stepped. It
allows the use of inexpensive LED light sources and connector
alignment and coupling is less critical than single mode fiber.
Distances of transmission and transmission bandwidth are less than
with single mode fiber due to dispersion.
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- NA
- see Numerical Aperture
- N connector
- A coaxial connector used for Ethernet 10Base5 thick
coax segments.
- Nanometer (nm)
- One billionth of a meter.
- Nanosecond (ns)
- One billionth of a second.
- NBR
- Butadiene-acrylonitrile copolymer rubber, a material
with good oil and chemical resistance.
- Near-End Crosstalk
- Crosstalk between two twisted pairs measured at the
same end of the cable as the disturbing signal source. NEXT is the
measurement of interest for crosstalk specifications.
- NEC
- National Electrical Code.
- NEMA
- National Electrical Manufacturers Association.
- Neoprene
- A synthetic rubber with good resistance to oil,
chemical, and flame. Also called polychloroprene.
- Network
- An interconnection of computer systems, terminals or
data communications facilities.
- Network Interface Card
- A circuit board installed in a computing device used
to attach the device to a network. A NIC performs the hardware
functions that are required to provide a computing device with
physical communications capabilities. Also Network Interface Unit (NIU).
- NEXT
- see Near-End Crosstalk.
- NFPA
- National Fire Protection Association
- NRZI
- Non Return to Zero Inverted.
- Numerical Aperture (NA)
- The "light gathering ability" of an optical
fiber, defining the maximum angle to the fiber axis at which light
will be accepted and propagated.
- NVP
- Nominal Velocity of Propagation. The speed a signal
propagates through a cable expressed as a decimal fraction of the
speed of light in a vacuum.
- Nylon
- An abrasion resistant thermoplastic with good
chemical resistance.
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- OFSTP
- Optical Fiber Standard Test Procedure.
- Ohm
- The electrical unit of resistance. The value of
resistance through which a potential of one volt will maintain a
current of one ampere.
- Ohm's Law
- Stated E=IR, I=E/R, or R=E/I, the current
"I" in a circuit is directly proportional to the voltage
"E", and inversely proportional to the resistance
"R".
- OLTS
- Optical Loss Test Set
- Optical Fiber
- A thin glass or plastic filament used for the
transmission of information via light signals. The signal carrying
part of a fiber optic cable.
- Optical Fiber Cable
- An assembly consisting of one or more optical fibers.
- Optical Fiber Duplex Adapter
- A mechanical media termination device designed to
align and join two duplex connectors.
- Optical Fiber Duplex Connection
- A mated assembly of two duplex connectors and a
duplex adapter.
- Optical Fiber Duplex Connector
- A mechanical media termination device designed to
transfer optical power between two pairs of optical fibers.
- Optical Time Domain Reflectometry.
- A method for evaluating optical fiber based on
detecting and measuring backscattered (reflected) light. Used to
measure fiber length and attenuation, evaluate splice and connector
joints, locate faults, and certify cabling systems.
- Outside Plant
- Cabling, equipment, or structures that are out of
doors.
- OTDR
- Optical Time Domain Reflectometry.
- Outlet
- A connecting device in the work area on which a
horizontal cable terminates.
- Outlet Box
- A metallic or non-metallic box mounted within a wall,
floor, or ceiling used to hold outlet, connector, or transition
devices.
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- PABX
- Private Automatic Branch Exchange
- Packet
- Bits grouped serially in a defined format, containing
a command or data message sent over a network.
- PAM5x5
- Signal encoding scheme used in the Ethernet
100Base-T2 and 1000Base-T media systems.
- Patch Cable, Patch Cord
- A flexible piece of cable terminated at both ends
with connectors. Used for interconnecting circuits on a patch panel or
cross connect.
- Patch Panel
- A passive device, typically flat plate holding feed
through connectors, to allow circuit arrangements and rearrangements
by simply plugging and unplugging patch cables.
- Plastic Fiber
- An optical fiber made of plastic rather than glass.
- Plasticizer
- A chemical added to plastics to make them softer and
more flexible.
- Plenum
- The air handling space between the walls, under
structural floors, and above drop ceilings used to circulate and
otherwise handle air in a building. Such spaces are considered plenums
only if they are used for air handling. Work spaces are generally not
considered plenums.
- POF
- Plastic Optical Fiber.
- Polybutadiene
- A type of synthetic rubber often blended with other
synthetic rubbers to improve their properties.
- Potting
- Sealing by filling with a substance to exclude
moisture.
- Propagation Delay
- Time required for a signal to pass from the input to
the output of a device.
- Protector
- A device that limits damaging voltages on metallic
conductors.
- Protocol
- A set of agree-upon rules and message formats for
exchanging information among devices on a network.
- PSELFEXT
- Power Sum Equal Level Far End Crosstalk
- PSNEXT
- Power Sum Near End Crosstalk
- PVC
- Polyvinyl Chloride
- PVDF
- Polyvinylidene Fluoride
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- Quartet Signaling
- The signaling method used by 100VG-AnyLAN, in which
the 100 Mbps signal is divided into four 25 Mbps channels and then
transmitted over different pairs of a cable. Category 3 cables
transmit one channel on each of four pairs.
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- R
- Symbol for Resistance
- Reflection
- A return of electromagnetic energy that occurs at an
impedance mismatch in a transmission line, such as a LAN cable.
- Refractive Index.
- The ratio of the speed of light in a vacuum to its
velocity in a transmitting medium, such as an optical fiber core.
- Repeater
- A device that receives, amplifies (and sometimes
reshapes), and retransmits a signal. It is used to boost signal levels
and extend the distance a signal can be transmitted. It can physically
extend the distance of a LAN or connect two LAN segments.
- Resistance
- In dc circuits, the opposition a material offers to
current flow, measured in ohms. In ac circuits, resistance is the real
component of impedance and may be higher than the value measured at
dc.
- Resonance
- An ac circuit condition in which inductive and
capacitive interact to cause a minimum or maximum circuit impedance.
- Retractile Cord
- A cord having specially treated insulation or jacket
so that it will retract like a spring. Retractibility may be added to
all or part of a cord's length.
- Reversed Pair
- A wiring error in twisted pair cabling where the
conductors of a pair are reversed between connector pins at each end
of a cable.
- Ring
- 1. A polarity designation of one wire of a pair
indicating that the wire is that of the secondary color of a 5-pair
group (e.g. the blue white wire of the blue pair). 2. A wiring contact
to which the ring wire is attached. 3. The negative wiring polarity
(see Tip).
- Ring Network
- A network topology in which terminals are connected
in a point-to-point serial fashion in an unbroken circular
configuration. Many logical rings are wired as a star for greater
reliability.
- Ripcord
- A cord placed directly under the jacket of a cable in
order to facilitate stripping (removal) of the jacket.
- Riser
- The conduit or path between floors of a building into
which telephone, networking, and other utility cables are placed to
bring service from one floor to another.
- Riser Cable
- A type of cable used in vertical building shafts,
such as telecommunications and utility shafts. Riser cable typically
has more mechanical strength than general use cable and has an
intermediate fire protection rating.
- RJ
- A term from the telephone industry, used for jacks
(connectors) that were registered for use with particular types of
telephone services. RJ stands for "registered jack".
- RJ-45
- A USOC code identifying an 8-pin modular plug or jack
used with unshielded twisted pair cable. Officially, an RJ-45
connector is a telephone connector designed for voice grade circuits
only. RJ-45 type connectors with better signal handling
characteristics are called 8-pin connectors in most standards
documents, though most people continue to use the RJ-45 name for all
8-pin connectors.
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- SC Connector
- A fiber optic connector having a 2.5mm ferrule,
push-pull latching mechanism, and the ability to be snapped together
to form duplex and multifiber connectors. SC connectors are the
preferred fiber optic cable for premises cabling, and are recommended
by the TIA/EIA-568-A Standard for structured cabling. Used with
Ethernet 100Base-FX and 1000Base-LX/SX fiber optic media systems.
- Scanner
- A cable testing device which uses TDR methods to
detect cable transmission anomalies and error conditions.
- Screen
- see Shield
- Screened Twisted Pair (ScTP) cable
- Four pair UTP, with a single foil or braided screen
surrounding all four pairs in order to minimize EMI radiation or
susceptibility. Screened twisted pair is sometimes called Foil Twisted
Pair (FTP). ScTP can be thought of as a shielded version of the
Category 3, 4, & 5 UTP cables.
- Screened/Shielded Twisted Pair (SSTP)
- Four pair cabling, with each pair having its own
individual Shield, in addition to an overall shield surrounding all
four pairs. SSTP offers similar performance to Type 1 STP except with
4 pairs (rather than 2) and in a 100 ohm impedance (rather than 150).
- ScTP
- see Screened Twisted Pair cable
- SDH
- see Synchronous Digital Hierarchy.
- Sheath
- see Jacket
- Shield
- A metallic foil or multiwire screen mesh that is used
to prevent electromagnetic fields from penetrating or exiting a
transmission cable. Also referred to as a "screen".
- Shield Coverage
- The physical area of a cable that is actually covered
by shielding material, often expressed as a percentage.
- Shield Effectiveness
- The relative ability of a shield to screen out
undesirable interference. Frequently confused with the term shield
coverage.
- Shielded Twisted Pair (STP)
- A type of twisted pair cable in which the pairs are
enclosed in an outer braided shield, although individual pairs may
also be shielded. STP most often refers to the 150 ohm IBM Type 1, 2,
6, 8, & 9 cables used with Token Ring networks.
- Single Mode Fiber
- An optical fiber that will allow only one mode to
propagate. The fiber has a very small core diameter of approximately 8
µm. It permits signal transmission at extremely high bandwidth and
allows very long transmission distances.
- Single-ended
- An unbalanced circuit or transmission line, such as a
coaxial cable transmission line (see also Balanced Line).
- Sinusoidal
- A signal which varies over time in proportion to the
sine of an angle. Ordinary alternating current is sinusoidal.
- Skew Rays
- A ray that does not intersect the fiber axis.
Generally, a light ray that enters the fiber at a very high angle.
- Skin Effect
- The tendency of alternating current to travel on the
surface of a conductor as the frequency increases.
- SMA Connector
- A threaded type fiber optic connector. The 905
version is a straight ferrule design, whereas the 906 is a stepped
ferrule design.
- Source
- In fiber optics, the device which converts the
electrical information carrying signal to an optical signal for
transmission over an optical fiber. A fiber-optic source may be a
light emitting diode or laser diode.
- Spectral Bandwidth
- The difference between wavelengths at which the
radiant intensity of illumination is half its peak intensity.
- Spectrum
- Frequencies that exist in a continuous range and have
a common characteristic. A spectrum may be inclusive of many spectrums
(e.g. the electromagnetic radiation spectrum includes the light
spectrum, radio spectrum, infrared spectrum, etc.)
- Splice
- A joining of conductors generally from separate
sheaths.
- Splice Closure
- A device used to protect a cable or wire splice.
- Split Pair
- A wiring error in twisted pair cabling where one of a
pair's wires is interchanged with one of another pair's wires. Split
pair conditions may be determined with a transmission test. Simple DC
continuity testing will not reveal the error, because the correct
pin-to-pin continuity exists between ends. However, the error may
result in impedance mismatch, excessive crosstalk, susceptibility to
interference, and signal radiation.
- SRL
- see Structural Return Loss
- SSTP, S/STP
- see Screened/Shielded Twisted Pair
- ST Connector
- Designation for the "straight tip"
connector developed by AT&T. This fiber optic connector features a
physically contacting non-rotating 2.5mm ferrule design and bayonet
connector-to-adapter mating. Used with Ethernet 10Base-FL and FIORL
links.
- Star Network
- A network in which all stations are connected through
a single point.
- Star Topology
- A topology in which each outlet/connector is wired
directly to the distribution device.
- Static Charge
- An electrical charge that is bound to an object. An
unmoving electrical charge.
- Station
- A unique, addressable device on a network.
- Stitching
- The activity of terminating multiconductor cables on
a punchdown block.
- STP-A
- Refers to the enhanced IBM Cabling System
specifications with the Type "A" suffix. The original IBM
Type 1, 2, 6, & 9 specifications were designed to support
operation of 4 and 16 Mbps Token-Ring. The enhanced Type 1A, 2A, 6A,
& 9A cable specifications were designed to support operation of
100 Mbps FDDI signals over copper.
- Structural Return Loss (SRL)
- A measure of the impedance uniformity of a cable. It
measures energy reflected due to structural variations in the cable. A
higher SRL number indicates better performance (more uniformity and
lower reflections).
- Structured Wiring
- Telecommunications cabling that is organized into a
hierarchy of wiring termination and interconnection structures. The
concept of structured wiring is used in the common standards from the
TIA and EIA.
- STS-n
- Synchronous Transport Signal-n (see Optical
Carrier-n).
- Subminiature D Connector
- A family of multipin data connectors available in 9,
15, 25 and 37 pin configurations. Sometimes referred to as DB9, DB15,
DB25 and DB37 connectors respectively.
- Synchronous
- Transmission in which the data character and bits are
transmitted at a fixed rate with the transmitter and receiver being
synchronized.
- Synchronous Digital Hierarchy (SDH)
- International standard for optical digital
transmission at hierarchical rates from 155 Mbps to 2.5 Gbps and
beyond.
- Synchronous Optical Network (SONET)
- A USA standard for optical digital transmission at
hierarchical rates from 155 Mbps to 2.5 Gbps and beyond.
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- TC
- Telecommunications Cross Connect.
- Telecommunications Closet
- see Closet
- Telecommunications Equipment Room
- see Equipment Room
- Terminal
- 1. A point at which information may enter or leave a
communications network. 2. A device by means of which wires may be
connected to each other.
- Terminator
- A device that provides electrical resistance at the
end of a transmission line. Its function is to absorb signals on the
line, thereby keeping them from bouncing back and being received again
by the network.
- Thicknet
- Ethernet 10Base5 coaxial cable.
- Thinnet
- Ethernet 10Base2 coaxial cable.
- 1. A polarity designation of one wire of a pair
indicating that the wire is that of the primary (common) color of a
5-pair group (e.g. the white-blue wire of the blue pair). 2. A wiring
contact to which the tip wire is connected. 3. The positive wiring
polarity (also see "ring").
- twork through a token passing scheme. Uses a
star-wired ring topology.
- Topology
- The physical or logical interconnection pattern of a
network.
- Transfer Impedance
- For a specified cable length, transfer impedance
relates to a current on one surface of a shield to the voltage drop
generated by this current on the opposite surface of the shield.
Transfer impedance is used to determine shield effectiveness against
both ingress and egress of interfering signals. Shields with lower
transfer impedance are more effective than shields with higher
transfer impedance.
- Tree Topology
- LAN topology similar to linear bus topology, except
that tree networks can contain branches with multiple nodes.
- Triaxial Cable, Triax
- Triax cable is coax cable with an additional outer
copper braid insulated from signal carrying conductors. It has a core
conductor and two concentric conductive shields.
- Triboelectric Noise
- Noise generated in a shielded cable due to variations
in capacitance between the shield and conductor as the cable is
flexed.
- Twisted Pair
- A multiple conductor cable whose component wires are
paired together, twisted, and enclosed in a single jacket. Each pair
consists of two insulated copper wires twisted together. When driven
as a balanced line, the twisting reduces the susceptibility to
external interference and the radiation of signal energy. Most
twisted-pair cabling contains either 2, 4, or 25 pairs of wires.
- Tx
- Transmit
- Type N Connector
- A threaded barrel constant impedance coaxial
connector for large diameter cable such as Ethernet 10Base5 thicknet
cable.
- Type 1
- 150 ohm shielded twisted pair (STP) cabling
conforming to the IBM Cabling System Specifications. Two twisted pairs
of 22 AWG solid conductors for data communications are enclosed in a
braided shield covered with a sheath. Tested for operation up to 16
MHz. Available in plenum, non-plenum, riser, and outdoor versions.
- Type 1A
- Enhanced version of IBM Type 1 cable rated for
operation up to 300 Mhz. Meets electrical specifications for 150 ohm
STP-A Cable as documented in the TIA/EIA 568-A standard.
- Type 2
- 150 ohm shielded twisted pair (STP) cabling
conforming to the IBM Cabling System specifications. Two twisted pairs
of 22 AWG solid conductors for data communications are enclosed in a
braided shield. Four additional pairs of 22 AWG solid conductors for
telephones are also included in the cable jacket but outside the
braided shield. Tested for operation up to 16 MHz. Available in plenum
and non-plenum versions.
- Type 2A
- Enhanced version of IBM Type 2 cable rated for
operation up to 300 Mhz. Meets electrical specifications for 150 ohm
STP-A Cable as documented in the TIA/EIA 568-A standard.
- Type 3
- IBM Cabling System designation for 100 ohm unshielded
twisted pair (UTP) cabling similar to TIA/EIA Category 3 cabling. 22
AWG or 24 AWG conductors with a minimum of two twists per linear foot.
Typically four twisted pairs enclosed within cable jacket.
- Type 5
- 100/140 micron optical fiber cable conforming to the
IBM Cabling System specifications. Two optical fibers are surrounded
by strength members and a polyurethane jacket. Type 5J is a 50/125
micron version defined for use in Japan.
- Type 6
- 150 ohm shielded twisted pair (STP) cabling
conforming to the IBM Cabling System specifications. Two twisted pairs
of 26 AWG stranded conductors for data communications. Flexible for
use in making patch cables. Tested for operation up to 16 MHz.
Available in non-plenum version only.
- Type 6A
- Enhanced version of IBM Type 6 cable rated for
operation up to 300 Mhz. Meets electrical specifications for 150 ohm
STP-A Cable as documented in the TIA/EIA 568-A standard.
- Type 8
- 150 ohm under-carpet cable conforming to the IBM
Cabling System Specifications. Two individually shielded parallel
pairs of 26 AWG solid conductors for data communications. The cable
includes "ramped wings" to minimize visibility when
installed under carpeting. Tested for operation up to 16 MHz.
- Type 9
- 150 ohm shielded twisted pair (STP) cabling
conforming to the IBM Cabling System Specifications. A plenum rated
cable with two twisted pairs of 26 AWG solid or stranded conductors
for data communications enclosed in a braided shield covered with a
sheath. Tested for operation up to 16 MHz.
- Type 9A
- Enhanced version of IBM Type 9 cable rated for
operation up to 300 Mhz. Meets electrical specifications for 150 ohm
STP-A Cable as documented in the TIA/EIA 568-A standard.
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- UL
- Underwriters Laboratories, Inc.
- Unbalanced Line
- A transmission line in which voltages on the two
conductors are unequal with respect to ground. Generally one of the
conductors is connected to a ground point. An example of an unbalanced
line is a coaxial cable.
- Underground Cable
- Cable that is intended to be placed beneath the
surface of the ground in ducts or conduit. Not necessarily intended
for direct burial in the ground.
- Unilay
- A conductor with more than one layer of helically
laid wires with the direction of lay and length of lay the same for
all layers.
- Unshielded Twisted Pair (UTP)
- Twisted pair cabling that includes no shielding. UTP
most often refers to the 100 ohm Category 3, 4, & 5 cables
specified in the TIA/EIA 568-A standard.
- USOC
- Universal Service Order Code. Pronounced
"U-Sock". An old Bell System term used to identify a
particular service or device offered under tariff. Often used to refer
to an old cable color code scheme that was current when USOC codes
were in use.
- UTP
- see Unshielded Twisted Pair.
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- V
- Symbol for Volt.
- VA
- Volt-ampere. A designation of power in terms of
voltage and current.
- Velocity of Propagation
- The transmission speed of electrical energy in a
length of cable compared to speed in free space. Usually expressed as
a percentage. Test devices use velocity of propagation to measure a
signal's transit time and thereby calculate the cable's length.
- VGM
- Voice Grade Media (see Voice Grade)
- VHF
- Very high frequency. The portion of the
electromagnetic spectrum extending from 30 to 300 MHz.
- Video
- A signal which contains visual information, such as a
picture in a television system.
- Voice Grade
- A term used for twisted-pair cable used in telephone
systems to carry voice signals.
- Volt
- The unit of electrical potential. One volt is the
electrical potential that will cause one ampere of current to flow
through one ohm of resistance.
- Voltage
- Electrical potential expressed in Volts.
- Voltage Drop
- The voltage developed across a component by the
current flow through the resistance of the component.
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- W
- Symbol for Watt or Wattage
- W
- White
- Watt
- A unit of electrical power. One watt is equivalent to
the power represented by one ampere of current flowing through a load
with a voltage drop of one volt in a dc circuit.
- Wave Form
- A graphical representation of the amplitude of a
signal over time.
- Wavelength
- The distance between successive peaks or nodes of a
wave.
- Wavelength Division Multiplexing
(WDM)
- The process of combining and splitting signals on the
basis of difference in their wavelengths.
- WAN
- Wide Area Network. A network connecting computers
within very large areas, such as states, countries, and the world.
- wire fault
- An error condition caused by a break in the wires or
a short between the wires (or shield) in a segment of cable.
- Wiring Closet
- see Closet
- Work Area
- That area of the premises cabling where users are
located. The area from the communications outlet to the equipment
connected to the premises cabling. Loosely, an office, cubicle, and so
forth.
- Workgroup
- A collection of workstations and servers on a LAN
that are designated to communicate and exchange data with one another.
- Workstation
- A computer connected to a network at which users
interact with software stored on the network.
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