Guided Transmission Media

1. Name:
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 Any thing that carry information from one
location to another is known as Transmission
Media.
Example Air.
In data communication it may be defined as
means by which Signals(information) are
carried from one system to another.

3. Classification of Transmission media
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Radio/Microwave

4. GUIDED MEDIA
In Bounded Media physical links are established to
transmit information from one device to another. It
includes twisted-pair cable, coaxial cable, and fiber-
optic cable.
•Twisted pair and coaxial cable use copper conductors
and transmits signals in the form of electric current.
•Optical fiber transports signals in the form of light.
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5. Guide Media - Twisted Pair
Twisted pair consists of two conductors (copper).
Each wire has its own insulation and are twisted
together.
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6. Twisted pair
 One of the wires carries signal,
the other is used only as a
ground reference.
 The receiver uses the difference
b/w the two.
 Twisting increases possibility
that both wires are equally
affected by Noise, thus the
difference at the receiver
remains same.
 Therefore, number of twists per
unit length determines the
quality of the cable.
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7. Unshielded Versus Shielded Twisted-Pair Cable
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8. Unshielded Twisted Pair (UTP)
 It was invented by
Alexander Graham
Bell.
 Most common cable
used in computer
networking and
Telephone systems
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10. Shielded Twisted Pair (STP)
 It has a Metal foil or
sheathing that reduces
the noise and thus
improves the quality of
Cable.
 Used only by IBM
 More expensive
 Harder to handle
(thick, heavy)
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11. Guided Media – UTP
UTP Connector
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13. Twisted Pair - Pros and Cons
 Most preferred medium
 Cheapest
 Easiest to install
 For local area networks (LAN)
 Suffers from external EM interference
 Less Bandwidth
 Short range
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14. Guided Media – Coaxial Cable
Coaxial Cable
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15. Coaxial Cable
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Coaxial cable was invented by English engineer and
mathematician H.Oliver in 1880.
Instead of two wires it has one central core
conductor.

16. Coaxial cable
 Inner conductor is a
solid wire outer
conductor serves as
conductor as well as
shield against noise.
 Whole cable is
protected by a plastic
cover.
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Attenuation is much higher in coaxial cable and thus
Repeaters are required frequently.

19. Coaxial Cable Pros and Cons
 Its versatile medium
 Television distribution
 Long distance telephone transmission
 Can carry 10,000 voice calls simultaneously
 Local area networks
Coaxial cable insulation may degrade, requiring
replacement of the cable.
Despite being shielded, interference can occur on
coaxial cable lines.
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20. Guided Media – Coaxial Cable
BNC Connectors
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21. BNC connectors
 BNC = Bayone-Neill-
Concelman
 BNC Connector is used to
connect the end of the
cable to a device
 BNC T is used in networks
to branch out a cable for
connection to a computer
or other device
 BNC Terminator is used at
the end of the cable to
prevent the reflection of
signal.
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22. Guided Media – Fiber-Optic Cable
Bending of light ray
It works on the principle of total internal reflection
Fiber-optic cable transmit signals in the form of light.
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23. 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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24. Guided Media – Fiber-Optic Cable
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25. Optical Fiber
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An optical fiber cable has a cylindrical shape
and consists of three concentric sections:
the core, the cladding, and the jacket.

26. OPTICAL FIBER CONSTRUCTION
a) Core:Thin glass center of the fiber where light travels
(high refractive index).The core has a diameter in the
range of 8 to 50 µm..
b) Cladding: Outer optical material surrounding the core
(low refractive index).
c) Buffer Coating: Plastic coating that protects
the fiber. Buffer coating
cladding
core
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27. Transmitters
light-emitting diodes (LEDs)
laser diodes
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28. Receivers
 The main component of an optical receiver is a
photodetector that converts light into electricity
through the photoelectric effect.
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29. Fiber-Optic Cable
 Two popular connectors used with fiber-optic cable:
 ST connectors (Straight Tip) used for networking devices
 SC connectors (Standard / Subscriber) used for cable TV
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30. Areas of Application
a) Telecommunications
b) Local Area Networks
c) Cable TV
d) CCTV
e) Medical Education
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31. Advantages of Optical Fibre
a) Thinner
b) Higher Carrying Capacity
c) Less Signal Degradation
d) Light Signals
e) Non-Flammable
f) Light Weight
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32. Disadvantages of fiber optics
 Unidirectional propagation.
 Expensive over short distance.
 Requires highly skilled installers.
 Adding additional nodes is difficult.
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33. Guided Media – Fiber-Optic Cable
Propagation Modes
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34. Guided Media – Fiber-Optic Cable
Propagation Modes
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35. STEP-INDEX
 In step-index fiber the density of central core remains
uniform . An outside cladding that also has a uniform
refractive index surrounds the core;
 However, the refractive index of the cladding is less
than that of the central core which result in abrupt
change .
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36. GRADED-INDEX
 In graded-index fiber, the density of the core varies
continuously. Density is highest at the center of core.
 This causes light rays to bend smoothly as they
approach the cladding, rather than reflecting abruptly
from the core-cladding boundary.
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37. Optical Fiber Transmission Modes
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38. • Data communication and Networking
By : BEHROUZ A FOROUZAN

39. THANK - YOU
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