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Network cabling
Physical Transmission
Physical Transmission
Physical Transmission
Transmission Media Signaling Techniques
Wire Wireless
Coaxial cable
UTP
STP
Fiber Optic
Baseband
Transmission
Broadband
Transmission
Radio waves
Microwave
Infrared
Cable types
The primary cable types:
coaxial
Twisted-pair unshielded twisted-pair Shielded twisted-pair
Fiber optic
The coaxial cable
The most widely used network cabling. it is inexpensive. Light Flexible Easy to work with.
The coaxial cable
The coaxial cable consist of : Core consist of solid copper surrounded by
insulation, braided metal shielding and an outer cover for protection.
The coaxial cable
Shielding protects transmitted data by absorbing the noise.
The core of coaxial cable carries the electronic signals which make up data.
The core wire can be either solid or copper.
The coaxial cable
The core is surrounded by a dielectric insulation which separate it from the wire mesh.
The wire mesh protects the wire core from the noise and crosstalk.
Crosstalk is signal overflow from an adjacent wire. The entire cable is surrounded by a non-conducting
outer shield, made from rubber or plastic.
The coaxial cable
The coaxial cable is good for longer distances and for reliably supporting higher data rates with less sophisticated equipment.
Types of coaxial cable Thin (thinnet). Thick (thicknet).
Coaxial cable consideration
It is used when you need: A medium that will transmit voice, video and
data. To transmit data longer distances than less
expensive cabling can do Data security.
Twisted pair cable
It consists of two insulated strands of copper wire twisted around each other.
The twisting cancels out the electronic noise from adjacent pairs and from other sources .
Types of Twisted pair cable
Unshielded twisted pair cable (UTP). Shielded Twisted pair cable (STP).
Unshielded twisted pair cable (UTP)
It is the most popular type of twisted-pair and also the most popular one for LAN cabling.
The maximum cable length for this type is 100 meters.
It consist of two unshielded copper wires.
Shielded twisted pair cable (STP).
This type uses a jacket which is a higher-quality and more protective than UTP.
It uses a foil wrap between and around the wire pairs.
Therefore, STP is excellent in protecting data from outside interference.
Twisted pair cabling components
Hardware connection: RJ-45 RJ-11
RJ-45 differ from RJ-11 in that it is larger, and will not fit in the RJ-11 telephone jackt.
RJ-45 houses eight cable connections while RJ-11 houses only four .
RJ-11RJ-45
Twisted pair cabling consideration
Use Twisted pair if: Budget limitation. Easy installation is required.• Do not use it if : High data integrity is required with high speed
and long distance.
Fiber-optic cable
In this kind of cables, optical fibers carry digital data signals in a form of modulated
pulses of light. It is more safe than other kinds of cables,
because no electronic impulses are carried over the fiber-optic cable.
Therefore, data can’t be stolen.
Fiber-optic cable
It consist of : outer jacket Kevlar strands to strength the cable Plastic coating to cushion the fiber The fiber is at the center consist of cladding and core
Fiber-optic cable
Each glass strand passes signals in only one direction. Therefore, a cable consist of two strands one for sending and one for receiving data.
Fiber-optic consideration
Use fiber-optic if: Need to transmit data in a high speed over
long distance. In a very secure media .
Don’t use it if: tight budget. Don’t have the expertise available to install it
properly.
Wireless Transmission
Unguided Media: transport electromagnetic waves without the use of a physical conductor.
Transmission is sent and received through invisible waves
Less expensive than copper or fiber optic lines. Allows the user to move freely around the office or
campus and still remain connected to the network Fastest-growing segment of network media today
Wireless Transmission
1. Radio waves
Radio waves are omnidirectional. The radio wave band is under government regulation.
Radio waves are used for multicast communications, such as radio and television, and paging systems.
Frequencies range between 3 KHz and 1 GHz.
2. Microwaves
consist of number of dishes installed on high towers or high places
distance must be 50 kilometers or less. Its fast but it may have noise and
interference Microwaves are used for unicast
communication such as cellular telephones, satellite networks, and wireless LANs
3 .Infrared
Frequencies between 300 GHz to 400 Thz. Can not penetrate walls. Infrared signals can be used for short-range
communication in a closed area.
Signal Transmission
There are two techniques used to transmit the encoded signals over cable:
Baseband Broadband
I. Baseband Signaling Sends one data signal across the network media. Entire capacity of the media is used for the one data
signal Signals are transmitted in a digital format . Many devices can send and receive across the
medium, but only one at a time. Baseband:
Uses Digital Signaling Single Frequency Transmits Bi-directionally Uses Repeaters
I. Baseband Signaling
II. Broadband Signaling Divides the cable into several different channels. Signals are transmitted at different frequencies in an analog
mode. Allows many different signals to be sent simultaneously on a
single cable. Signal sent in only one direction. Used for computer network data transmissions. Broadband
Uses Analog Signaling Multiple Frequencies Transmits Uni-directionally Uses Amplifiers
II. Broadband Signaling
Factors Affecting Transmissions
The flow of a signal down the network media can become distorted.
Common types of distortions are:
a) attenuation
b) interference.
a) Attenuation Loss of signal power Measured by the decrease in decibels (db) over a
specific distance
b) Interference Interference is caused when a strong external signal
interferes with a signal. Radio frequency interference (RFI) - interference
caused by broadcast signals from a radio or television transmitter.
Electromagnetic interference (EMI) - motor or source of intense electrical activity creates an electromagnetic signal that interferes with a data signal.
Near end crosstalk (NEXT) and Far end crosstalk (FEXT) - interference from another data signal being transmitted on adjacent wire.