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Telecommunication
How It works
What It is?
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Telecommunication, devices and systems
that transmit electronic or optical signals
across long distances. such as a telephone
system.
enables people to send and receive
personal messages .
key medium for delivering news, data,
information, and entertainment.
Way of sending Message
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Point-to-point : One sender to a
single receiver such as telephone
conversation;
Point-to multi point : one sender to
many receiver such as television, It
often called Broadcast;
How the signals sent?
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Telecommunications devices convert
different types of information, such as
sound and video, into electronic or optical
signals.
Electronic signals travel along a medium
such as copper wire or are carried over the
air as radio waves. Optical signals travel
along optical fiber cable;
the device on the receiving end converts the
signal back into an understandable
message, such as words and pictures on a
computer screen.
Types of signal
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Analog signal
Digital signal
Optical signal
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analog or digital
refers to the
method used to
convert information
into an electrical
signal
Analog signal
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An analog signal is any continuously variable
signal
in an analog sound recording, the variation in
pressure of a sound striking a microphone creates
a corresponding variation in the current passing
through it. An increase in the volume of the sound
causes the fluctuation of the current to increase
Digital signal
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0 volt
means 0
5 volts
means 1
Optical signal
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Pulse beam of laser
light
LED (Light Emitting
Diode) send signal
Fiber optic receiver
Receive fiber optic
signals
Transmission medium
Cable
Fiber-optic
Micro-wave
Satellite
Coaxial cable
 Developed in 1936
 Made of copper wire
 Expensive
Fiber Optics
Message are digitally coded
into pulses of light
TAT 9 fiber optic cable can
carry more than 75,000
telephone conversation at a
time
Microwave relay
 Relay from station to station
 Needs a clear line of sight
between sending and
receiving station
 Average distance between
stations 40km
 As many as 600 telephone
conversations can be
transmitted over one
microwave relay channel.
Satellite communication
 Started at 1969
with series of
satellites
 Orbit 35,880km
above the earth
 Powered by solar
energy
 Use micro wave
for transmission
 can relay up to
33,000 calls
simultaneously
as well as
several television
channels.
Way of transmission
 Simplex: One way
communication
 Half Duplex:
communications in
both directions, but
only one direction at
a time
 Duplex:
communication in
both directions
simultaneously
Applications
Telegraph
Fax
Telephone
Radio
Television
Global Positioning System
Voice Over IP
Computer network
Telephone & cellular
Communication
Global Positioning System
 space-based radionavigation system
consisting of 24
satellites and
ground support.
 accurate
information about
their position, time,
anywhere in the
world and in all
weather conditions.
How GPS Works
 GPS satellites fly in circular orbits at an
altitude of 20,100 km (12,500 mi) and
with a period of 12 hours
 point their solar panels toward the sun
and their antennas toward the earth
 Send the signals to the receiver
 From that signal receiver calculate its
position on earth
Application of GPS
 Military equipment such as fighters, bombers,
tankers, helicopters, ships, submarines, tanks,
jeeps, and soldiers
 Airplane and ships use it for route navigation
 used to route and monitor delivery vans and
emergency vehicles
 car navigation system
 Because the GPS user does not need to
communicate with the satellite, GPS can serve
an unlimited number of users.
Inventor
In 1837 Samuel
Morse invented the
first workable
telegraph
 Alexander Graham
Bell invented
telephone in 1876
 Marconi invented
Radio in 1895
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