Basics of Satellite Communication

7/31/2019 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

Documents

Basics of Satellite Communication