Presentation on Transmission Media

Group : Silent Hunter
Group Member :
• Syed Ahmed Zaki ID:131-15-2169
• Fatema Khatun ID:131-15-2372
• Sumi Basak ID:131-15-2364
• Priangka Kirtania ID:131-15-2385
• Afruza Zinnurain ID:131-15-2345
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Acknowledgement
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Md. Sarwar Jahan Morshed
Assistant Professor
Dept. Of Computer Science and
Engineering
Daffodil International University

Content
 Transmission Media
 Guided Media:
 Twisted Pair
 UTP
 STP
 Co-Axial Cable
 Fibre Optic Cable
 Propagartion Modes
 Transmission Impairment
 Unguided Media:
 Propagation Methods
 Radio Waves
 Antenna
 Microwaves
 Infrared
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What is Tranmission Media ?
In data communication,
• Transmission media is a pathway that carries the
information from sender to receiver.
• We use different types of cables or waves to
transmit data.
• Data is transmitted normally through electrical or
electromagnetic signals.
5

Description
• Transmission media are located below the physical
layer
• Computers use signals to represent data.
• Signals are transmitted in form of electromagnetic
energy.
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Classification of Transmission media
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Twisted-pair cable
 A twisted pair consists of two conductors
 Basically copper based
 With its own plastic insulation, twisted together.
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Twisted Pair Description
• Provide protection against cross talk or
interference(noise)
• One wire use to carry signals to the receiver
• Second wire used as a ground reference
• For twisting, after receiving the signal remains same.
• Therefore number of twists per unit length, determines
the quality of cable.
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Twisted Pair
Advantages:
• Cheap
• Easy to work with
Disadvantages:
• Low data rate
• Short range
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Twisted Pair - Applications
• Very common medium
• Can be use in telephone network
• Connection Within the buildings
• For local area networks (LAN)
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Twisted Pair Cables
Twisted Pair cables
Unshielded
Twisted Pair
(UTP)
Shielded
Twisted pair
(STP)
12

Unshielded Twisted Pair (UTP):
Description
• Pair of unshielded wires
wound around each
other
• Easiest to install
13

Applications
UTP :
 Telephone subscribers connect to the central telephone
office
 DSL lines
 LAN – 10Mbps or 100Mbps
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UTP Cable Types
Cat 7
Cat 6
Cat 5e
Cat 5
Cat 2
Cat 3
Cat 4
Cat 1
UTP
Cat means category according to IEEE standards. IEEE is de jure standard
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UTP connector and Tools
RJ45 (RJ stands for registered jack) is a keyed connector, it
means that it can be inserted in only one way
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Crimper Tool

Advantages of UTP:
 Affordable
 Most compatible cabling
 Major networking system
Disadvantages of UTP:
• Suffers from external Electromagnetic interference
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Shielded Twisted Pair (STP)
• Pair of wires wound
around each other
placed inside a
protective foil wrap
• Metal braid or sheath
foil that reduces
interference
• Harder to handle
(thick, heavy)
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STP Application
• STP is used in IBM token ring networks.
• Higher transmission rates over longer distances.
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Advantages of STP:
 Shielded
 Faster than UTP
Disadvantages of STP:
 More expensive than UTP
 High attenuation rate
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Co-axial Cable
Co-axial cable carries signal of higher frequency ranges than twisted
pair cable
• Inner conductor is a solid wire
• Outer conductor serves as a shield against noise and a second
conductor
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Categories of coaxial cables
Coaxial cables are categorized by Radio Government (RG) ratings,
RG is De Jure standards
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Coaxial Cable Connectors
BNC Connectors – Bayone Neil Concelman
To connect coaxial cable to devices we need coaxial connectors
 BNC Connector is used at the end of the cable to a device
Example: TV set conenction
 BNC T connector used to Ethernet networks to branch out
connection to computer or other devices
 BNC terminator is used at the end of the cable to prevent the
reflection of the signal
24

Coaxial Cable Applications
• Most versatile medium
• Television distribution
• Long distance telephone transmission
• Can carry 10,000 voice calls simultaneously
• Short distance computer systems links
• Local area networks
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COAXIAL CABLE
ADVANTAGES
 Easy to wire
 Easy to expand
 Moderate level of Electro Magnetic Interference
DISADVANTAGE
 Single cable failure can take down an entire network
 Cost of installation of a coaxial cable is high due to its
thickness and stiffness
 Cost of maintenance is also high
26

Fiber-Optic Cable
A fiber optic cable is made of glass or plastic and transmit signals in
the form of light.
Nature of light:
 Light travels in a straight line
 If light goes from one substance to another then the ray of light changes
direction
 Ray of light changes direction when goes from more dense to a less dence
substance
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Bending of light ray
• Angle of Incidence (I): the angle the ray makes with the line
perpendicular to the interface between the two substances
• Critical Angle: the angle of incidence which provides an
angle of refraction of 90-degrees.
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Optical fiber
• Uses reflection to guide
light through a channel
• Core is of glass or
plastic surrounded by
Cladding
• Cladding is of less
dense glass or plastic
An optical fiber cable has a cylindrical shape
and consists of three concentric sections:
the core, the cladding, and the jacket(outer
part of the cable).
Jacket
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Fiber – Optic cable Connectors
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Subscriber Channel (SC) Connecter
Straight-Tip (ST) Connecter
Same szie as RJ45 connector

Areas of Application
 Telecommunications
 Local Area Networks
 Cable TV
 CCTV
 Medical Education
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Optical Fiber Advantages
 Greater capacity
Example: Data rates at 100 Gbps
 Smaller size & light weight
 Lower attenuation
 Electromagnetic isolation
 More resistance to corrosive materials
 Greater repeater spacing facility
Example: After every 10s of km at least
33

Optical Fiber Disadvantages
• Installation and maintenance need expertise
• Only Unidirectional light propagation
• Much more expensive
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Propagation Modes
When signal goes from one point to another there are need for
propagation modes.
Propagation Modes
Multimode Single Mode
Step -Index Graded - Index
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Transmission Impairment
• The Imperfection in transmission media causes
signal impairment
• What is sent is not what is received
due to impairment
• Three causes of impairement are
1)Attenuation,
2)Distortion
3)Noise
ATTENUATION
DISTORTION
NOISE
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Transmission Impairment
• Attenuation means a loss of energy.
• Distortion means that the signal changes its form or
shape.
• Noise is another cause of impairement.
• Several types of noise
Example: thermal noise, induced noise, crosstalk
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Unguided Media: Wireless Transmission
Unguided media transport electromagnetic waves without using a
physical conductor it is known as wireless communication.
Signals broadcast through free space and available to capable receiver
Electro magnetic spectrum for wireless communication:
Radio wave & Micro wave Infrared
3 kHz 300GHz 400THz 900THz
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Propagation methods
Unguided signals travels from the source to destination in
several ways it is known as propagation.
They are three types:
 Ground propagation
 Sky propagation
 Line-of-Sight Propagation
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Ground propagation:
 Radio waves travel through the
lowest portion of the
atmosphere
 Touching the earth.
Sky propagation:
 Radio waves radiate to the
ionosphere then they are
reflected back to earth.
Line-of-Sight Propagation:
 In straight lines directly from
antenna to antenna.
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Bands using propagation method
Band Range Propagation Application
VLF 3–30 KHz Ground Long-range radio navigation
LF 30–300 KHz Ground
Radio beacons and
navigational locators
MF 300 KHz–3 MHz Sky AM radio
HF 3–30 MHz Sky
Citizens band (CB),
ship/aircraft communication
VHF 30–300 MHz
Sky and
line-of-sight
VHF TV,
FM radio
UHF 300 MHz–3 GHz Line-of-sight
UHF TV, cellular phones,
paging, satellite
SHF 3–30 GHz Line-of-sight Satellite communication
EHF 30–300 GHz Line-of-sight Long-range radio navigation
42

Unguided Media
Wireless transmission waves
43

Unguided Media – Radio Waves
 Omnidirectional Antenna
 Frequencies between 3
KHz and 1 GHz.
 Used for
multicasts(multiple way)
communications, such as
radio and television, and
paging system.
 Radio waves can
penetrate buildings easily,
so that widely use for
indoors & outdoors
communication.
44

Antennas
An Antenna is a structure that is generally a metallic object may be a
wire or group of wires, used to convert high frequency current into
electromagnetic waves.
Antenna are two types:
• Transmission antenna
 Transmit radio frequency from transmitter
 Radio frequency then
Convert to electromagnetic energy by antenna
 Then, radiate into surrounding environment
• Reception antenna
 Electromagnetic energy get in antenna
 Then Antenna convert radio frequency to electrical energy
 Then, Goes to receiver
same antenna can be used for both purposes
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Microwaves are ideal when large areas need to be covered
and there are no obstacles in the path
46
Microwaves

Micro waves Transmission
• Microwaves are unidirectional
• Micro waves electromagnetic waves having frequency between
1 GHZ and 300 GHZ.
• There are two types of micro waves data communication system
: terrestrial and satellite
• Micro waves are widely used for one to one communication
between sender and receiver,
example: cellular phone, satellite networks and in wireless
LANs(wifi), WiMAX,GPS
47

Infrared
 Frequencies between 300 GHz to 400 THz.
 Used for short-range communication
 Example: Night Vision Camera,Remote control,
File sharing between two phones,
Communication between a PC and peripheral
device,
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References
 Data communication and Networking,
fourth edition
By : BEHROUZ A FOROUZAN
 And various relevant websites
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