The document discusses different types of transmission media including guided media like twisted pair cable, coaxial cable, fiber optic cable and unguided media like radio waves, microwaves, and infrared. It provides details on each medium like their construction, applications, advantages and disadvantages. It also discusses concepts like propagation modes, transmission impairment and electromagnetic spectrum used for wireless communication. Satellite communication is discussed along with different types of satellites based on their orbit - geostationary, medium earth orbit and low earth orbit satellites.

1. TransmissionTransmission
MediaMedia
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2. ContentContent
 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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3. What is Tranmission Media ?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.
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4. DescriptionDescription
• 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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5. Classification of Transmission mediaClassification of Transmission media
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6. Twisted-pair cable
 A twisted pair consists of two conductors
 Basically copper based
 With its own plastic insulation, twisted together.
6

7. Twisted Pair DescriptionTwisted 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.
7

8. Twisted Pair
Advantages:
•Cheap
•Easy to work with
Disadvantages:
•Low data rate
•Short range
8

9. Twisted Pair - Applications
• Very common medium
• Can be use in telephone network
• Connection Within the buildings
• For local area networks (LAN)
9

10. Twisted Pair CablesTwisted Pair Cables
Twisted Pair cables
Unshielded
Twisted Pair
(UTP)
Shielded
Twisted pair
(STP)
10

11. Unshielded Twisted Pair (UTP):
Description
• Pair of unshielded wires
wound around each
other
• Easiest to install
11

12. ApplicationsApplications
UTP :
Telephone subscribers connect to the central telephone
office
DSL lines
LAN – 10Mbps or 100Mbps
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13. UTP Cable TypesUTP Cable Types
Cat 7
Cat 6
Cat 5e
Cat 5
Cat 4
Cat 3
Cat 2
Cat 1
UTP
Cat means category according to IEEE standards. IEEE is de jure standard
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14. Categories of UTP cables
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15. 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
15
Crimper Tool

16. Advantages of UTP:
 Affordable
 Most compatible cabling
 Major networking system
Disadvantages of UTP:
•Suffers from external Electromagnetic interference
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17. 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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18. STP ApplicationSTP Application
• STP is used in IBM token ring networks.
• Higher transmission rates over longer distances.
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19. Advantages of STP:
 Shielded
 Faster than UTP
Disadvantages of STP:
 More expensive than UTP
 High attenuation rate
19

20. Co-axial cable carries signal of higher frequency ranges than twisted
pair cable
Co-axial Cable
• Inner conductor is a solid wire
• Outer conductor serves as a shield against noise and a second
conductor
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21. Categories of coaxial cables
Coaxial cables are categorized by Radio Government (RG) ratings,
RG is De Jure standards
21

22. BNC Connectors – Bayone Neil Concelman
Coaxial Cable Connectors
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
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23. 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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24. 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
COAXIAL CABLE
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25. 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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26. 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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27. 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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28. Fiber Construction
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29. Fiber – Optic cable Connectors
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Subscriber Channel (SC) Connecter
Straight-Tip (ST) Connecter
Same szie as RJ45 connector

30. Areas of ApplicationAreas of Application
 Telecommunications
 Local Area Networks
 Cable TV
 CCTV
 Medical Education
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31. Optical Fiber AdvantagesOptical 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
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32. Optical Fiber DisadvantagesOptical Fiber Disadvantages
• Installation and maintenance need expertise
• Only Unidirectional light propagation
• Much more expensive
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33. Propagation Modes
Propagation Modes
Multimode Single Mode
Step -Index Graded - Index
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When signal goes from one point to another there are need for
propagation modes.

34. Propagation Modes
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35. Transmission ImpairmentTransmission Impairment
• The Imperfection in transmission media causes
signal impairment
• What is sent is not what is received
due to impairment
• Three causes of impairment are
1)Attenuation,
2)Distortion
3)Noise
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36. • 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
Transmission ImpairmentTransmission Impairment
36

37. Unguided Media: Wireless Transmission
3 kHz 300GHz 400THz 900THz
Radio wave & Micro wave Infrared
Electro magnetic spectrum for wireless communication:
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
37

38. 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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39. 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.
39

40. Bands using propagation methodBands using propagation method
BandBand RangeRange PropagationPropagation ApplicationApplication
VLFVLF 3–30 KHz Ground Long-range radio navigation
LFLF 30–300 KHz Ground
Radio beacons and
navigational locators
MFMF 300 KHz–3 MHz Sky AM radio
HFHF 3–30 MHz Sky
Citizens band (CB),
ship/aircraft communication
VHFVHF 30–300 MHz
Sky and
line-of-sight
VHF TV,
FM radio
UHFUHF 300 MHz–3 GHz Line-of-sight
UHF TV, cellular phones,
paging, satellite
SHFSHF 3–30 GHz Line-of-sight Satellite communication
EHFEHF 30–300 GHz Line-of-sight Long-range radio navigation
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41. Unguided MediaUnguided Media
Wireless transmission waves
41

42.  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.
Unguided Media – Radio WavesUnguided Media – Radio Waves
42

43. 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
AntennasAntennas
43

44. InfraredInfrared
 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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45. Microwaves are ideal when large areas need to be covered
and there are no obstaclesno obstacles in the path . Microwaves are
unidirectional.
45
Microwaves

46. Microwave Transmission
Above 100 MHz, the waves travel in nearly straight lines
and can therefore be narrowly focused.
The microwaves formed the heart of the long-distance
telephone transmission system.
Microwaves travel in a straight line, so repeaters are
needed periodically. For 100-meter-high towers, repeaters
can be 80 km apart.
At lower frequencies, microwaves do not pass through
buildings well. The delayed waves may arrive out of phase
with the direct wave and thus cancel the signal. This effect
is called multipath fading.

47. • Micro waves have the frequency between 1 GHZ and
300 GHZ.
• 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

48. Advantages
No need to lay down cables.
Microwave is also relatively inexpensive. Putting up
two simple towers and putting antennas on each one
may be cheaper than burying 50 km of fiber through a
congested urban area or up over a mountain.
48

49. The Politics of the Electromagnetic Spectrum
National governments allocate spectrum for AM and
FM radio, television, and mobile phones, as well as for
telephone companies, police, maritime, navigation,
military, government, and many other competing users.
Worldwide, an agency of ITU-R (WRC) tries to
coordinate this allocation. Accordingly, most
governments have set aside some frequency bands,
called the ISM (Industrial, Scientific, Medical) bands
for unlicensed usage. Garage door openers, cordless
phones, radio-controlled toys, wireless mice, and
numerous other wireless household devices use the ISM
bands.
49

50. Politics of the Electromagnetic
Spectrum
The ISM bands in the United States.

51. Infrared and Millimeter Waves
Unguided infrared waves are widely used for short-
range communication.
The remote controls used for televisions, VCRs, and
stereos all use infrared communication.
They are relatively directional, cheap, and easy to
build
No government license is needed to operate
an infrared system, in contrast to radio systems.
51

52. Major drawback:
 They do not pass through solid objects. It is also a
plus. It means that an infrared system in one room of a
building will not interfere with a similar system in
adjacent rooms or buildings.
 Infrared communication has a limited use on the
desktop, for example, to connect notebook computers
and printers with the IrDA (Infrared Data
Association) standard, but it is not a major player
in the communication game.
52

53. Lightwave Transmission
Unguided optical signaling
free-space optics has been in use for centuries.
A more modern application is to connect the LANs in
two buildings via lasers mounted on their rooftops.
 Optical signaling using lasers is inherently
unidirectional, so each end needs its own laser and its
own photodetector.
53

54. Lightwave Transmission
Convection currents can interfere with laser
communication systems.
A bidirectional system with two lasers is pictured here.

55. Advantage:
This scheme offers very high bandwidth at very low
cost .
It is relatively secure because it is difficult to tap a
narrow laser beam.
 It is also relatively easy to install and does not
require an FCC(Federal communication Commission)
license.
Disadvantage:
 It cannot penetrate rain or thick fog, although they
normally work well on sunny days.
The laser’s strength, a very narrow beam, is also its
weakness here.
55

56. COMMUNICATION SATELLITES
In the 1950s and early 1960s, people tried to set up communication
systems by bouncing signals off metallized weather balloons. The key
difference between an artificial satellite and a real one is that the
artificial one can amplify the signals before sending them back,
turning a strange curiosity into a powerful communication system.
A communication satellite can be thought of as a big microwave
repeater in the sky. It contains several transponders, each of which
listens to some portion of the spectrum, amplifies the incoming
signal, and then rebroadcasts it at another frequency to avoid
interference with the incoming signal. This mode of operation is
known as a bent pipe.
Each transponder can use multiple frequencies and polarizations to
increase the available bandwidth.
56

57. Communication Satellites
• Geostationary Satellites
• Medium-Earth Orbit Satellites
• Low-Earth Orbit Satellites
• Satellites versus Fiber

58. Communication Satellites
Communication satellites and some of their properties,including altitude
above the earth, round-trip delay time and number of satellites needed
for global coverage.

59. Geostationary Satellites
In 1945, the science fiction writer Arthur C. Clarke describes a
complete communication system that used these (manned)
geostationary satellites, including the orbits, solar panels, radio
frequencies, and launch procedures. Unfortunately, he concluded
that satellites were impractical due to the impossibility of putting
power-hungry, fragile vacuum tube amplifiers into orbit.The invention
of the transistor changed all that, and the first artificial
communication satellite, Telstar, was launched in July 1962. Since
then, communication satellites have become a multibillion dollar
business and the only aspect of outer space that has become highly
profitable. These high-flying satellites are often called GEO
(Geostationary Earth Orbit) satellites.
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60. Communication Satellites (2)
The principal satellite bands.

61. Communication Satellites (3)
VSATs using a hub.

62. Medium-Earth Orbit Satellites
 (Medium-Earth Orbit) satellites are at lower altitudes, between the
two Van Allen belts.
 As viewed from the earth, these drift slowly in longitude, taking
something like 6 hours to circle the earth.
 Accordingly, they must be tracked as they move through the sky.
Because they are lower than the GEOs, they have a smaller footprint
on the ground and require less powerful transmitters to reach them.
 Currently they are used for navigation systems.
 The 24 GPS (Global Positioning System) satellites orbiting at about
18,000 km are examples of MEO satellites.
62

63. Low-Earth Orbit Satellites
Moving down in altitude, we come to the LEO (Low-
Earth Orbit) satellites.
Due to their rapid motion, large numbers of them are
needed for a complete system.
The satellites are so close to the earth, the ground
stations do not need much power, and the round-trip
delay is only a few milliseconds.
The launch cost is substantially cheaper too.
Examples  voice service, Iridium and Globalstar
63

64. Iridium
For the first 30 years of the satellite era, low-orbit satellites
were rarely used because they zip into and out of view so
quickly.
In 1990, Motorola decided to launch 77 low-orbit satellites
for the Iridium project (element 77 is iridium).
The plan was later revised to use only 66 satellites, so the
project should have been renamed Dysprosium (element
66).
The idea was that as soon as one satellite went out of view,
another would replace it.
Everyone wanted to launch a chain of low-orbit satellites.
The communication service began in November 1998.
The Iridium service restarted in March 2001 and has been
growing ever since. 64

65. Low-Earth Orbit Satellites
Iridium
(a) The Iridium satellites from six necklaces around the
earth.

66. It provides voice, data, paging, fax, and navigation
service everywhere on land, air, and sea, via hand-held
devices that communicate directly with the Iridium
satellites.
Customers include the maritime, aviation, and oil
exploration industries, as well as people travelling in
parts of the world lacking a telecom infrastructure.
(e.g., deserts, mountains, the South Pole, and some
Third World countries).
The Iridium satellites are positioned at an altitude of
750 km, in circular polar orbits.
66

67. They are arranged in north-south necklaces, with one
satellite every 32 degrees of latitude.
Each satellite has a maximum of 48cells (spot beams)
and a capacity of 3840 channels, some of which are
used for paging and navigation, while others are used
for data and voice.
Each satellite has four neighbours .With six satellite
necklaces the entire earth is covered.
An interesting property of Iridium is that
communication between distant customers takes
place in space.
67

68. Globalstar
An alternative design to Iridium is Globalstar.
It is based on 48 LEO satellites but uses a different
switching scheme than that of Iridium.
Iridium relays calls from satellite to satellite, which
requires sophisticated switching equipment in the
satellites, but ,Globalstar uses a traditional bent-pipe
design.
The call originating at the North Pole in Fig. 2-19(b) is
sent back to earth and picked up by the large ground
station.
The call is then routed via a terrestrial network to the
ground station nearest the callee and delivered by a
bent-pipe connection as shown. 68

69. Globalstar
(a) Relaying in space.
(b) Relaying on the ground.

70. The advantage of this scheme is that it puts much of the complexity on
the ground, where it is easier to manage.
Also, the use of large ground station antennas that can put out a
powerful signal and receive a weak one means that lower-powered
telephones can be used.
Teledesic
Teledesic is for high bandwidth internet users.
Conceived by Craig McCaw and Bill Gates.
It provides the internet users with 100 Mbps uplink and 720 Mbps
downlink.
It uses a small, fixed ,VSAT-type antenna.
Here transmission occurs in the uncrowded and high bandwidth Ka
band.
The system is packet-switched in space.
70

71. Satellites Versus Fiber
Telephone companies began replacing their long-haul
networks with fiber and introduced high-bandwidth
services like ADSL (Asymmetric Digital Subscriber
Line). They also stopped their long-time practice of
charging artificially high prices to long-distance users
to subsidize local service.
First, satellites provide a quick response which is
useful for military communication systems in times of
war and disaster response in times of peace.
Communications satellites are useful during the
massive December 2004 Sumatra earthquake and
subsequent tsunami. 71

72.  A second niche is for communication in places where the terrestrial
infrastructure is poorly developed.
For example ,Indonesia has its own satellite for domestic telephone traffic.
 A third niche is for mobile communication
 Many people nowadays want to communicate everywhere they go.
 Mobile phone networks cover those locations with good population density.
 Conversely, Iridium provides voice service everywhere on Earth,even at the
South Pole.
 A fourth niche is when broadcasting is essential.
 Satellites are used to distribute much network TV programming to local
stations for this reason.
 For example, an organization transmitting a stream of stock, bond, or
commodity prices to thousands of dealers might find a satellite system to be
much cheaper than simulating broadcasting on the ground.
 A fifth niche is to cover area where fiber is difficult to lay.
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