Glossary
Capacitance
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B-3
Capacitance
A measurement of the capacity to store electrical charge across conductive elements that
are separated by an insulating material (dielectric). Undesirable capacitance that occurs
between conducting wires in a network cable results in capacitive coupling, which causes
crosstalk between cable pairs.
Channel
A network connection consisting of (1) a patch cable to a horizontal cross-connect, (2) two
connections at the cross-connect, (3) a horizontal cable segment up to 90m (295 ft), (4) a
transition connector near the telecommunications outlet, and (5) a telecommunications
outlet. Cable test limits for a channel are looser than those for a basic link because the
channel limits allow for the effects of two connections at the cross-connect and an extra
connector near the telecommunications outlet.
Characteristic Impedance
The total opposition (dc resistance and ac reactance) to the flow of ac current that a
network cable would have if the cable were infinitely long.
Coaxial Cable
A type of transmission cable in which an inner conductor is surrounded first by an
insulating layer, then by a braided, conductive sheath. The braided sheath acts as a shield
that protects the inner conductor from electrical noise. Coaxial cables typically have a
wide bandwidth. Two types of coaxial cable are used with Ethernet networks: Thicknet
(10Base5 standard) and Thinnet (10Base2 standard).
Collision
The result of two stations simultaneously attempting to transmit data on a shared network
transmission medium (such as Ethernet).
Crossed Pair
A wiring error in twisted pair cabling where a pair on one end of the cable is wired to a
different pair in the connector on the other end of the cable.
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