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In recent years Communications Wire & Cable has become an essential
part of our lifestyle. Copper has been used for telecommunications
since 1877, when the first commercial telephone line was installed
in Boston, under the supervision of Alexander Graham Bell. Its
main advantages are high conductivity, being able to be drawn
into fine wires, compact size, resistance to creep and ease of
joining. Copper communications cables are insulated with various
materials, and may be an assembly of up to 4,200 pairs (8,400
conductors).
No longer do we live in a world of voice communication only. Today,
there is extensive data communication, as well as video over high-performance
twisted pair cables. Modern office complexes are the most advanced
examples of the communication evolution. What began with telephone
wiring systems, has now reached the stage where, to keep pace
and provide all the communications needs and flexibility, the
solution is integral structured wiring systems.
The accompanying schematic drawing illustrates sample floors of
a typical office tower, and the principal components of a structured
network communications system. The components are described on
these pages, together with details of the copper wire and cable
involved.
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Two sizes of riser cables, the multi-pair copper cables which
connect the Main Distribution Terminal to the Floor Terminals.
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Horizontal Distribution Systems…
These systems get their name from the fact that most of the runs
are horizontal in the floor/ceiling of the floor level. Premises
Communications Cables (PCC) link the Riser System Terminal, with
the individual workstations. A group of work-stations connected
together, is known as a Local Area Network (LAN).
There are two types of PCC:
Unshielded Twisted Pair Cables (UTP)
Shielded Twisted Pair Cables (STP)
Unshielded Twisted Pair Cables (UTP), have solid, annealed, tinned
or bare copper conductors, insulated with a variety of compounds.
There are five Categories of UTP Cables, based on capacity:
Category 1 - Analog voice systems, data up to 20 Kbps (thousands of bits/second).
Category 2 - Transmission characteristics not specified. Voice and data
systems up to 4 Mbps (millions of bits/second).
Category 3 - Transmission characteristics specified up to 16 MHz (millions
of Hertz), support voice and data systems up to 10 Mbps @ maximum
100 m.
Category 4 - Transmission characteristics specified up to 20 MHz, support
voice and data systems up to 16 Mbps @ maximum 100 m.
Category 5 - Transmission characteristics specified up to 100 MHz, support
voice and data systems up to 100 Mbps @ 100 m maximum run length.
Desired transmission properties in the UTP Cables are low signal
attenuation and low crosstalk couplings between pairs. While crosstalk
is primarily a nuisance in voice transmission, it can lead to
corruption of data during transmission. In a typical UTP Cable
there are four pairs of copper conductors. One pair is used for
data transmission, and another for data reception. The remaining
two pairs can be used for powering equipment, or to support other
applications which use different pair assignments.
Shielded Twisted Pair Cables have the addition of laminated polyester/aluminum
tape shields over all of the twisted pairs.
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| Two examples of Copper UTP (Unshielded Twisted Pair) Cables. |
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