Satellite communication provides long distance communication by using satellites to transmit signals between locations on Earth. There are three types of satellites - active satellites that amplify and change the frequency of signals, passive satellites that simply reflect signals, and broadcasting satellites used for radio and television. Satellites orbit Earth in different patterns depending on their inclination and eccentricity. Key elements of satellite communication systems are the space segment including satellites, and the ground segment including earth stations. Satellite communication services can be one-way, such as broadcasting, or two-way, such as telephone calls.

1. SATELLITE COMMUNICATION – an Overview
A TECHNICAL SEMINAR
BY
V sasank chaitanya kumar,

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3. Introduction
The never ending quest of communication engineer is to
transmit maximum information in short time to the
largest possible distance,this gave raise to many
systems of communications.
Disadvantages of exisiting broad band methods:
 Coaxial cables,Fiberoptics - Wiring problem
 Microwaves - LOS

4. Defination of satellite
 Satellite can be defined as a heavy object which goes around
object in space due to the effect of mutual gravitational
forces,used for broadband communication.
Why satellites came into picture??
 This is because the earth is like a sphere
 As we know radio waves travel in straight lines at micro
wave
frequenices
 A repeater is needed to convey signal over long distance
 Satellites are used to link places on earth that are thousands
of miles a part

5. Need of satellite for long distance communication

6. Types of Satellites
 Active satellite
It is one in which the signal is amplified and its
frequency changed by transponder,before itsent back to
earth. Example:communication,broadcasting satellites
 Passive satellite
These type of satellites simply reflects or scatters the
micro wave signal back to another station
Example:military and non profitable servieces

7. Satellite pictures
October 1957, the first The first artificial passive In July 1962 active satellite
artificial satellite Sputnik satellite Echo-I of NASA was Telstar was developed and
-I was launched by launched in August 1960. launched
former Soviet Russia.

8. Advantages of Satellites
 The advantages of satellite communication over
terrestrial communication are:
 The coverage area of a satellite greatly exceeds that
of a terrestrial system.
 Transmission cost of a satellite is independent of the
distance from the center of the coverage area.
 Higher Bandwidths are available for use.

9. Disadvantages of Satellites
 Launching satellites into orbit is costly.
 Satellite bandwidth is gradually becoming
used up.
 There is a larger propagation delay in
satellite communication than in terrestrial
communication.

10. Satellite Transmission Bands
Frequency Band Downlink Uplink
C 3.7-4.2 GHz 5.92-6.42 GHz
Ku 11.7-12.2 GHz 14.0-14.5 GHz
Ka 17.7-21.2 GHz 27.5-31.0 GHz
The C band is the most frequently used. The Ka and Ku bands are reserved exclusively
for satellite communication but are subject to rain attenuation

11. Types of Satellite Orbits
 Based on the inclination, i, over the equatorial plane:
 Equatorial Orbits above Earth’s equator (i=0°)
 Polar Orbits pass over both poles (i=90°)
 Other orbits called inclined orbits (0°<i<90°)
 Based on Eccentricity
 Circular with centre at the earth’s centre
 Elliptical with one foci at earth’s centre

12. What is Apogee and Perigee?

13. Where satellites are placed?
Satellite orbits are also classified in terms of the orbital height. These are:

14. s1
Breif overview of orbits s2 s3

15. ELEMENTS OF SATELLITE COMMUNICATIONS SYSTEM
Two major elements of Satellite Communications Systems are:
 Space Segment
 Ground Segment
The Space Segment includes:
 Means for launching satellite
 Satellite(Transponders)
 Power supply system
The ground segment consists of:
 Earth Stations
 Rear Ward Communication links

16. Functioning of Transponder
TO /FROM
EARTH STATION

17. Power requriment
 Modern satellites use a variety of power means
 Solar panels are now quite efficient, so solar
power is used to generate electricity
 Batteries are needed as sometimes the
satellites are behind the earth - this happens about
half the time for a LEO satellite
 Nuclear power has been used - but not
recommended

18. Earth Station Block diagram

19. Earth stations

20. SATELLITE COMMUNICATION SERVICES
Different Satellite Communications services are classified as
 one way link
 Two way link.
One way link from transmitter Tx to receiver Rx on earth’s
surface

21. Examples of satellite services where the transfer of
information takes place through one way link are:
 Broadcast Satellite Service (Radio, TV, Data broadcasting)
 Data Collection Service (Hydro meteorological data collection)
 Space operations service, (Tracking, Telemetry, Command)
 Safety services (Search & Rescue, Disaster Warning)
 Earth Exploration Satellite Service (Remote Sensing)
 Radio Determination Satellite Service (Position location)
 Reporting Service (fleet monitoring)

22. Two-way Satellite Communications link
 Fixed Satellite Service (Telephone, telex, fax, high bit rate
data etc.)
 Mobile Satellite Service (Land mobile, Maritime, Aero-mobile,
personal communications)
Satellite News Gathering (Transportable and Portable )

24. Your Feedback on this session is Important
12/16/12 By Deepak 24
Poonam
sasank