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Computer Data / Voice
Network Cabling Glossary "B"
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D E F G H I J
K L M N O P Q
R S T U V W X
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c A small "c" is the symbol for the speed of
light in a vacuum.
C A capital "C" is the designation for celsius.
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.
Campus The buildings and grounds of a complex,
such as a university, college, industrial park or military
establishment.
Capacitance The ability to store electric charge
between two conductors separated by a dielectric material.
Capacitance is expressed in Farads.
Carrier An electrical signal of a set frequency
that can be modulated in order to carry data.
Carrier Detect A circuit that detects the presence
of a carrier.
Carrier Sense With Ethernet, a method of detecting
the presence of signal activity on a common channel.
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.
CATV Community antenna television, or "Cable
TV". CATV is a broadband transmission facility which generally
uses a 75 Ohm coaxial cable to carry numerous frequency-divided
TV channels simultaneously.
CBX Computerized Branch Exchange.
Cellular Polyethylene Expanded or "foam" polyethylene,
a material with a reduced dielectric constant consisting
of individual closed cells of inert gas suspended in a polyethylene
medium.
CDDI Copper Distributed Data Interface - A
version of FDDI that uses copper wire media instead of fiber
optic cable.
Channel The end to end transmission path between
two points at which application specific equipment is connected.
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.
Cheapernet Another name for thin Ethernet or
10Base2 systems.
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.
Chromatic Dispersion Synonym for "material
dispersion".
Circuit 1. A system of conducting media designed
to pass a signal or voltage between two points. 2. A bi-directional
communications path between two pieces of associated equipment.
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.
Coating Material surrounding the cladding of
the fiber for protection.
Coax, Coaxial Cable A type of communication
transmission cable in which a solid center conductor is
surrounded by an insulating spacer which in turn is surrounded
by a tubular outer conductor (usually a braid, foil or both).
The entire assembly is then covered with an insulating and
protective outer layer. Coaxial cables have a wide bandwidth
and can carry many data, voice and video conversations simultaneously.
Coherence Refers to the phase stability of
two wave trains, from the same optical wave, separated in
time
Collision When electrical signals from two
or more devices sharing a common data transfer medium crash
into one another. This commonly happens on Ethernet type
systems.
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.
Conductivity The ability of a material to allow
the flow of electrical current. It is the reciprocal of
resistivity. Measured in "mhos" (ohms backwards).
Conductor A material that offers low resistance
to the flow of electrical current.
Continuity An uninterrupted pathway for electrical
signals.
Cord A very flexible insulated cable.
Core The central region of an optical fiber
through which light is transmitted.
Coupling ratio The percentage of optical power
transferred to the secondary output port of a coupler relative
to the total power of the primary and the secondary output
ports.
CRC see Cyclic Redundancy Check
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.
Crossover A conductor which connects to a different
pin number at each end.
Crossover Cable A twisted pair patch cable
wired in such a way as to route the transmit signals from
one piece of equipment to the receive signals of another
piece of equipment, and vice versa.
Crosstalk The coupling of unwanted signals
from one pair within a cable to another pair. Crosstalk
can be measured at the same (near) end or far end with respect
to the signal source.
CSA Canadian Standards Association
CSMA/CD see Carrier Sense Multiple Access with
Collision Detect.
Current The flow of charge in a conductor.
See "alternating current" and "direct current".
Current Loop A two wire transmit/receive interface.
Customer Premises Buildings, offices, and other
structures under the control of a telecommunications customer.
Cutoff Wavelength A distinct boundary, in the
wavelength spectrum, which characterizes the mode of operation
of a fiber. A fiber operating at wavelengths lower than
the cutoff wavelength is multimode while the same fiber
operating at wavelengths higher than cutoff wavelength is
single mode.
Cut-through Resistance The ability of a material
to withstand mechanical pressure without damage.
Cyclic Redundancy Check (CRC) An error checking
technique used to ensure the accuracy of transmitting digital
code over a communications channel. The transmitted messages
are divided into predetermined lengths which, used as dividends,
are divided by a fixed divisor. The remainder of the calculation
is appended onto and sent with the message. At the receiving
end, the computer recalculates the remainder. If it does
not match the transmitted remainder, and error is detected.
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