Transcript An Introduction to Optical Fiber Communication

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Fundamental Ideas
What is Communication ??
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Exchange Of Information
What is Communication??
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Exchange Of Information
Audio
Data
I get it !!!!!!!!!!!!
My Information.
Video
Signal
Transmission Medium
Source
Free Space
Copper
Fiber Optic
Destination
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Transfer of information from one place to another
How to transfer information??
Some carrier is required to carry information over
long distances….
Why???
Limitation: Information cannot go beyond
certain distance without the aid of a carrier
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Through Some Carrier
Carrier
• Which is the most suitable carrier??
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• Should be capable of carrying information
• Can take it through long distance
• Should have good speed
Electromagnetic Wave
• Can carry any information through modulation
• Energetic - Can go through long distance
• Supports multiple media Eg: Free space/Copper/Fiber etc..
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• Highest Known speed 3x108m/s
Electromagnetic Wave
 Harmonic oscillations at atomic level gives oscillating
electric field
 Electromagnetic wave generation
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 In electromagnetic wave electrical and magnetic fields vary
harmonically
Relation between
electric and magnetic field
(Perpendicular)
So in electromagnetic wave electric and magnetic
fields oscillate perpendicular to each other and
electromagnetic energy transmits perpendicular to
both
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Changing electric field gives rise to changing
magnetic field & vise versa
Figure of a wave
Wavelength = distance travelled in one cycle(l)
Frequency = Number of cycles per second(n)
Velocity(v) = l x n
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l
Electro Magnetic Spectrum
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Velocity of all the electromagnetic wave is same, 3 x 108m/s
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Block Diagram of a
Telecommunication System
What is the other thing required apart from carrier for
transmitting signals over longer distances??
Some medium for carrying signals from transmitter to the
receiver
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Media…..
Different types of media used for transmitting
signals….
Tx
Carrier
MEDIA
•Wireless(Free space/air):Microwave
Satellite
Rx
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•Wired : Twisted Pair
Co-axial cable
Optical fiber
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Twisted Pair
Twisted Pair
 The insulated wires are twisted to form the
communication line,the purpose of twisting the wires
is to avoid electrical interference
 Twisted pair can be combined into a cable that may
consist of two,four,fifty or hundreds of pairs
 Twisted pair is the basis of transmission
media(Telephone)
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 Twisted pair is made of two copper wires which are
covered by plastics or materials that are similar
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Coaxial Cable
Coaxial Cable
 Coaxial cable contains two conductors which are
insulated from one another
 Coaxial cable has many applications,for instance
cable TV,local networks,short run computer system
links and long distance telephone transmission
 In local network coaxial cable can support different
type of traffic and data
 By using FDM,it can carry more than 10,000
channels at a time
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 The inner conductor is covered by the dielectric and
the outer conductor is covered by a shield
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Optic Fiber
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Optic Fiber(Physical Appearance)
Optic Fiber
Optic fiber is made up of 3 parts :
 The inner most part is the core which contains one
or more thin fibers that are made up of plastic or
glass
 Each of the fiber in the core is covered by a cladding
which has different optical properties from the core
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Core,Cladding and jacket
 The outer most part of the optical fiber is made up of
plastic or other materials ,which is called the jacket
Optic Fiber
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 Because of greater performance and higher data rate,the
application of optic fiber has dramatically increased in
long distance communication and military applications
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Microwave
Microwave
 Microwave antennas are equipped in higher place in
order to achieve better transmission effect
 Voice transmission,television transmission and the
short point to point links will be the major application
of microwave transmission
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 In terrestrial microwave transmission a pair of towers
mounted on top of the towers will transmit signals
through air
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Satellite Communication
Satellite
 The satellite will amplify or repeat the signal to other
frequency band,this action is called downlink
 A satellite link is called a microwave link
 The most application of satellite communication will
be long distance telephone transmission
 Private business networks and television distribution
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 A satellite consists of several transponders which
receive signal from one frequency band,this action is
called uplink
Comparison of Twisted Pair,Coaxial
Cable and Optic fiber
Coaxial Cable Optic Fiber
Data Rate/
Bandwidth
4Mbps
500Mbps
Upto
100Gbps
Repeater Spacing
1-10Km
1-10Km
10-100Km
Affected
Not affected
Electromagnetism Affected
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Twisted Pair
Optic Fiber
Satellite
Reconfiguration
Not possible
Possible
Bandwidth
Practically upto
10 GHz
36-72MHz
Weather Condition Affected by storm Not affected by
storm
Electromagnetic
Interference
Not affected
Affected
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Comparison of Satellite and Optic Fiber