Download - Basics of Satellite Communication
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Satellite communication
EC
4th year
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Contents
Communication
Types of communication
Frequency spectrum
Basics of satellite communication
Frequency bands
Advantages and disadvantages
Major problems
Applications
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Communication
The technique which helps to transfer
information from one place /node /terminal
/device to another is called communication.
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Types Of Communication
Wired
Wireless
Mobile
(890
MHz)
Satellite
(6/4 GHz)
Remote
(10^3 Hz)
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Frequency Spectrum
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Basics of satellite communication
Satellite: A celestial body that orbits a planet
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Why satellite communication?
Microwave band of frequency is used
High frequency waves travel in straight line
Earth is curved
Solution: satellite
An earth station transmits the signal up to thesatellite-called the up-link and is transmitted on
one frequency. The satellite receives the signal and retransmits it
on the down link which is on another frequency.
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Using a satellite for long distance communications
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Why not moon?
concept proved by naval research lab in Washington
D.C.by using moon in 1940s.
Surface of the moon is tough and uneven that most
of the signal scatters back into space instead of
bouncing back to earth. Moon can only reflect signals. Modern
communication satellites actively rebroadcast the
signal back to earth.
Moon is only available for half of the day, and it
keeps moving. Earth based antenna have to move to
track it.
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Frequency Bands
Name of the freq. band Range of freq.
1.) L 1-2(GHz)
2.) S 2-4(GHz)
3.) C 4-8(GHz)
4.) X 8-12(GHz)
5.) Ka 12-18(GHz)
6.) K 18-26(GHz)
7.) Ku 26-40(GHz)
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Advantages of satellite communication
Provision of service to remote or
underdeveloped area.
Transmission cost is independent of distance.
Higher bandwidth is available.
Larger coverage area than terrestrial network.
Independent from terrestrial infrastructure.
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Disadvantages of Satellite
Communication
Making and launching a satellite is a complex
and costly process.
Difficulty in troubleshooting a satellite.
Larger propagation delay is found in satellite
communication.
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Major problems in satellite
communication
Difficulty in designing and positioning a
satellite.
Less stability (due to difficulty in alignment
and direction of antenna).
Large power requirement.
Harsh climate affect transmission of signals.
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Applications
Weather forecasting
VSAT(very small aperture terminal)
Communication
Military and intelligence satellite
Research and development
Observation of distant stars and other objects
in space
GPS and navigation
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Thank you