1.3 Copper Cabling

Question 1

SIGNAL ATTENUATION

Answer 1

The farther the signal travels, the more it deteriorates.

Question 2

Electromagnetic interference (EMI) or radio frequency interference (RFI)

Answer 2

EMI and RFI signals can distort and corrupt the data signals being carried by copper media.
Potential sources of EMI and RFI include radio waves and electromagnetic devices, such as fluorescent lights or electric motors.

To counter the negative effects of EMI and RFI, some types of copper cables are wrapped in metallic shielding and require proper grounding connections.

Question 3

Crosstalk

Answer 3

Crosstalk is a disturbance caused by the electric or magnetic fields of a signal on one wire to the signal in an adjacent wire.

To counter the negative effects of crosstalk, some types of copper cables have opposing circuit wire pairs twisted together, which effectively cancels the crosstalk.

Question 4

UTP

Answer 4

Unshielded Twisted Pair

UTP cabling, terminated with RJ-45 connectors, is used for interconnecting network hosts with intermediary networking devices, such as switches and routers.

In LANs, UTP cable consists of four pairs of color-coded wires that have been twisted together and then encased in a flexible plastic sheath that protects the wires from minor physical damage. The twisting of wires helps protect against signal interference from other wires.

Question 5

STP

Answer 5

Shielded Twisted Pair

Shielded twisted-pair (STP) provides better noise protection than UTP cabling. However, compared to UTP cable, STP cable is significantly more expensive and difficult to install. Like UTP cable, STP uses an RJ-45 connector.

STP cables combine the techniques of shielding to counter EMI and RFI, and wire twisting to counter crosstalk. To gain the full benefit of the shielding, STP cables are terminated with special shielded STP data connectors. If the cable is improperly grounded, the shield may act as an antenna and pick up unwanted signals.

Question 6

Coaxial Cable

Answer 6

Coaxial cable, or coax for short, gets its name from the fact that there are two conductors that share the same axis. As shown in the figure, coaxial cable consists of the following:

A copper conductor is used to transmit the electronic signals.
A layer of flexible plastic insulation surrounds a copper conductor.
The insulating material is surrounded in a woven copper braid, or metallic foil, that acts as the second wire in the circuit and as a shield for the inner conductor. This second layer, or shield, also reduces the amount of outside electromagnetic interference.
The entire cable is covered with a cable jacket to prevent minor physical damage.
There are different types of connectors used with coax cable. The Bayonet Neill–Concelman (BNC), N type, and F type connectors are shown in the figure.

Although UTP cable has essentially replaced coaxial cable in modern Ethernet installations, the coaxial cable design is used in the following situations:

Wireless installations - Coaxial cables attach antennas to wireless devices. The coaxial cable carries radio frequency (RF) energy between the antennas and the radio equipment.
Cable internet installations - Cable service providers provide internet connectivity to their customers by replacing portions of the coaxial cable and supporting amplification elements with fiber-optic cable. However, the wiring inside the customer’s premises is still coax cable.