Unit 1: Introduction and Physical Layer Topic 6: Transmission (Guided Media) - I

1. SNS COLLEGE OF ENGINEERING
Kurumbapalayam(Po), Coimbatore – 641 107
Accredited by NAAC-UGC with ‘A’ Grade
Approved by AICTE, Recognized by UGC & Affiliated to Anna University, Chennai
Department of Information Technology
Course Name : CS8591 Computer Networks
III Year / V Sem
Unit 1: Introduction and Physical Layer
Topic 6: Transmission (Guided Media) - I
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2. Transmission
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The Oxford English Dictionary
“The action of transmitting or fact of being transmitted; conveyance from one person or place
to another; transference”
“Conveyance or passage through a medium, as of light, heat, sound, etc.; spec. in Radio and
Television; also, a series of electric signals or electromagnetic waves transmitted, a broadcast”

3. Transmission
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➢ Unified society
➢ Same content is being transmitted to the masses
➢ Passive
➢ Evolving technology is influencing the ways that an audience interacts
with media.

4. Howdoes transmission work?
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➢ Transmitter and Receiver
➢ Transmission medium, a path - Guided with wire or
unguided (wireless).
➢ The communication between the mediums is achieved by using
electromagnetic waves
Transmission Media

5. Electromagnetic Waves
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Electromagnetic waves or EM waves are waves that are created as a result of vibrations between an
electric field and a magnetic field.

6. Transmission Media
Networking cable
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Connectors Specification
Physical Layer

7. Transmission Media
➢ A communication channel.
➢Information from the sender to the
receiver.
➢ Data - Electromagnetic signals.
➢ Information in the form of bits .
Transmission Media
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8. Factors - Designing the Transmission Media
Bandwidth:
The greater the bandwidth of a medium, the higher the data transmission rate of
a signal.
Transmission impairment:
Quality of the signals will get destroyed due to transmission impairment.
Interference:
Disrupting a signal when it travels over a communication medium on the
addition of some unwanted signal.
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9. Causes of Transmission Impairment
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Attenuation
Distortion
Noise

10. Classification of Transmission Media
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11. Guided Media
The physical medium through which the
signals are transmitted.
It is also known as Bounded media.
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12. Twisted Pair
⮚ A physical media made up of a 8 wires twisted in pairs
⮚ Twisted
○ Reduce crosstalk
○ Improve data transmission performance
⮚Consists of four color insulated copper
○ Blue, Red, Green, Orange
○ Carry signal to receiver, ground reference.
○ Cheap as compared to other transmission media
⮚Installation is easy
⮚ It is a lightweight cable
⮚ The frequency range is from 0 to 3.5KHz.
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13. Types of Twisted Pair
Unshielded Twisted Pair:
An unshielded twisted pair is widely used in
telecommunication.
Shielded Twisted Pair
A shielded twisted pair is a cable that contains the mesh
surrounding the wire that allows the higher transmission
rate.
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14. Unshielded Twisted Pair
Shielded Twisted Pair
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15. Shielded Twisted Pair
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Outer layer is a plastic jacket or
Shield
Metallic substance, protect the cable from Electromagnetic
Interference (EMI)

16. Shielded Twisted Pair
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➢ Aluminium foil shielding
➢ Foil wraps individual wire
➢ Some STP may or may not have foil shielding
➢ Fully Shielded Twisted pair (FTP)
Copper conducted wire - Plastic insulator

17. Shielded Twisted Pair
Characteristics Of Shielded Twisted Pair:
⮚The cost is not very high and not very low.
⮚An installation of STP is easy.
⮚It has higher capacity as compared to unshielded twisted pair cable.
⮚It is shielded that provides the higher data transmission rate
Disadvantages
⮚It is more expensive as compared to UTP and coaxial cable.
⮚It has a higher attenuation rate.
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18. Unshielded Twisted Pair
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UTP has fewer layers of shielding
Two layers:
➢ Plastic layer and Wire insulator
➢ No additional shielding

19. Unshielded Twisted Pair
Categories of the unshielded twisted pair cable:
⮚Category 1: Used for telephone communications. Not suitable for transmitting data.
⮚Category 2: Capable of transmitting data at speeds up to 4 megabits per second (Mbps).
⮚Category 3: Used in 10BASE-T networks. Can transmit data at speeds up to 10 Mbps.
⮚Category 4: Used in Token Ring networks. Can transmit data at speeds up to 16 Mbps.
⮚Category 5: Can transmit data at speeds up to 100 Mbps.
⮚Category 5e: Used in networks running at speeds up to 1000 Mbps (1 gigabit per second [Gbps]).
⮚Category 6: Typically, Category 6 cable consists of four pairs of 24 American Wire Gauge (AWG) copper wires.
Category 6 cable is currently the fastest standard for UTP.
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20. Advantages:
⮚It is cheap.
⮚Installation of the unshielded twisted
pair is easy.
⮚It can be used for high-speed LAN.
Disadvantage:
⮚This cable can only be used for
shorter distances because of
attenuation.
Unshielded Twisted Pair
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21. ⮚ Throughput:
○ STP and UDP transmit at same rate
○ Factors - Level of cable category, cable quality, proper installation
⮚ Cost:
○ STP and UDP vary
○ STP more expensive in general
⮚ Connector:
○ STP and UDP use RJ-45
⮚ Noise and EMI resistance:
○ STP is more resistant
⮚ Size:
○ Length 100 meters
Shielded Twisted Pair vs
Unshielded Twisted Pair
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22. Coaxial Cable
⮚ Coaxial cable - TV wire is usually a coaxial cable.
⮚ The name of the cable is coaxial as it contains two conductors
parallel to each other.
⮚ It has a higher frequency as compared to Twisted pair cable.
⮚ The inner conductor - copper, outer conductor - copper
mesh, middle core - non-conductive cover that separates the
inner conductor from the outer conductor.
⮚ Middle core is responsible for the data transferring , the copper
mesh prevents from the EMI(Electromagnetic interference).
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23. Coaxial Cable
Outer cover - PVC or fire resistant plastic - Sheath
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Braided metal shielding reduces Electromagnetic
Interference (EMI)
Central metal core - copper conductor Coaxial cable - carry high frequency signals

24. Coaxial Cable Connectors
BNC - Bayonet Neil Concelman
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Type - N connectors, Weatherproof RF connector,
Carry Microwave signals
SMA - Subminiature version A, high
frequency microwave and WIFI systems Used to connect Cable modem

25. Types of Coaxial Cable
Baseband transmission:
It is defined as the process of transmitting a single signal at high speed.
Broadband transmission:
It is defined as the process of transmitting multiple signals simultaneously.
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26. Coaxial Cable
Advantages :
⮚The data can be transmitted at high speed.
⮚It has better shielding as compared to twisted pair cable.
⮚It provides higher bandwidth.
Disadvantages:
⮚It is more expensive as compared to twisted pair cable.
⮚If any fault occurs in the cable causes the failure in the entire network.
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27. Fibre Optic
⮚ Electrical signals for communication.
⮚ Optical fibres coated in plastic, send the
data by pulses of light.
⮚ The plastic coating protects the optical
fibres from heat, cold, electromagnetic
interference from other types of wiring.
⮚ Faster data transmission than copper
wires.
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28. Fibre Optic Cable
⮚ One or more optical cable that carry lights
⮚ Higher throughput than copper cable (Coaxial, Twisted cable)
⮚ Types:
○ Single mode - fiber enables one type of light mode to be
propagated at a time.
○ Multi mode - fiber can propagate multiple modes
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29. Fibre Optic Cable
Jacket - Protects inner components
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Buffer - encapsulate one or more optical fibre,
protect physical damage
Cladding - Glass or plastic shield, protect
the core
Core - Cylinder glass or plastic, light travelling in
the core

30. Basic Elements
➢ Core:
○ A narrow strand of glass or plastic known as a core.
○ A core is a light transmission area of the fibre.
○ The more the area of the core, the more light will be transmitted into the fibre.
➢ Cladding:
○ The concentric layer of glass is known as cladding.
○ Provide the lower refractive index at the core interface as to cause the reflection within the core so that the light
waves are transmitted through the fibre.
➢ Jacket:
○ The protective coating consisting of plastic is known as a jacket.
○ To preserve the fibre strength, absorb shock and extra fibre protection.
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31. Single Mode Fibre SMF
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➢ Carry light with single mode
➢ Light travel in sam way or same pattern
➢ Single ray of light

32. ⮚High transfer rate over long distance
⮚Core diameter, 9 microns.(width of single human hair - 20 to 200 microns)
⮚Laser generate light travels one path
⮚Light does not disperse as signal travels
⮚Carry signals many miles
⮚Better for long distance - WAN connection
⮚Patch cable - yellow color
SMF Features
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33. Multi Mode Fibre MMF
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➢ Used for communication over short distance , within building or campus
➢ Light waves dispersed in numerous paths or modes, travel through cable core
➢ Data rates upto 100 Gbps

34. ⮚Core with larger diameter than single mode
⮚Laser or LED generate light travels at different angles
⮚Greater attenuation
⮚Better for short distance
⮚Patch cable - orange color
MMF Features
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35. ⮚Advantages:
○ Greater Bandwidth: Carries more data as compared to copper cable.
○ Faster speed: Carry the signals at a higher speed.
○ Longer distances: Carries the data at a longer distance as compared to copper cable.
○ Better reliability: It is immune to any temperature changes while it can cause obstruct in
the connectivity of copper cable.
○ Thinner and Sturdier: It can withstand more pull pressure than copper cable
Fibre Optic
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36. 1. Which of this is not a guided media?
a) Fiber optical cable b) Coaxial cable c) Wireless LAN d) Copper wire
2. Transmission media are directly controlled by _________
a) Physical layer b) Data link c) Transport d) Network
layer
3. Transmission media can be divided in to __________
a) 1 b) 2 c) 3 d) 4
4. Which transmission media has the highest transmission speed in a network? __________
a) coaxial cable b) twisted pair cable c) optical fiber d) electrical cable
5. Which of the following is not a transmission medium?
a) telephone lines b) coaxial cables c) modem d) microwave systems
Puzzle
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37. THANK YOU !
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