A comprehensive presentation on Satellite Systems. It covers almost every aspect of technical details.

1. Satellite Systems
Presented By
Sorath Asnani
Mehran University of Engineering & Technology, Jamshoro

2. Contents
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Introduction to Satellites
Major types of Satellites
Working of Satellites
Satellite Communication
Satellite Frequency Bands
Satellite Orbits
Geocentric Orbits
Types of Satellites
Uses and Applications of Satellites
Conclusion
References
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3. What is satellite?
• Any object that revolves around a larger object in
space is called a satellite.
• A satellite travels in a special path, called its orbit.
Figure 1. Satellite
orbiting the Earth
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4. Major types of Satellite
1. Natural Satellites
2. Artificial Satellites
Figure 2. Natural Satellite
Figure 3. Artificial Satellite
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5. Natural Satellites
• There are about 173 known natural satellites orbiting
planets in the Solar System.
• All the planets that revolve around the Sun are Natural
Satellites.
• The Moon is the only Natural Satellite of the Earth.
Figure 4. Earth revolving around Sun
Figure 5. Moon revolving around
Earth
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6. First Artificial Satellite
• The world's first artificial satellite, the Sputnik 1, was
launched by the Soviet Union on October 4, 1957.
• It's primary purpose was to send back temperatures
of space.
• It was about the size of a basketball, weighed only
183 pounds, and took about 98 minutes to orbit the
Earth on its elliptical path.
Figure 6. The Sputnik 1
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7. How do Satellites work?
• Two Stations on Earth want to communicate
through radio broadcast but are too far away to
use conventional means.
• The two stations can use a satellite as a relay station
for their communication.
• One Earth Station transmits the signals to the
satellite. Up link frequency is the frequency at which
Ground Station is communicating with Satellite.
• The satellite Transponder converts the signal and
sends it down to the second earth station. This
frequency is called a Downlink frequency.
• The area which receives a signal of useful strength
from the satellite is known as the satellite's footprint.
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8. Satellite Communication
Advantages:
The advantages of satellite communication over
terrestrial communication are:
• The coverage area of a satellite is greater than 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
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9. Satellite Communication
Cont..
Disadvantages:
The disadvantages of satellite communication are:
• Cost involved in launching satellites into orbit is too
high
• There is a larger propagation delay in satellite
communication than in terrestrial communication
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10. Basics of Satellites
Figure 7. Working of Satellite
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11. Satellite Frequency Bands
Table 1. Satellite Frequency Bands
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12. Satellite Frequency Bands
Cont..
• The three most commonly used satellite frequency
bands are:
1. C-band
2. Ku-band
3. Ka-band
• C-band and Ku-band are the two most common
frequency spectrums used by today's satellites.
• There is an inverse relationship between frequency and
wavelength--when frequency increases, wavelength
decreases and vice versa.
• As wavelength increases (and frequency decreases),
larger antennas (satellite dishes) are necessary to gather
the signal.
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13. C - Band
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C-band satellite transmissions occupy the 4 to 8 GHz frequency
range.
These relatively low frequencies translate to larger wavelengths
than Ku-band or Ka-band.
These larger wavelengths of the C-band mean that a larger
satellite antenna is required to gather the minimum signal
strength, and therefore the minimum size of an average C-band
antenna is approximately 2-3 meters in diameter.
Figure 8.
C – Band Satellite Antenna
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14. Ku - Band
• Ku-band satellite transmissions occupy the 11 to 17 GHz
frequency range.
• These relatively high frequency transmissions correspond
to shorter wavelengths and therefore a smaller antenna
can be used to receive the minimum signal strength.
• Ku-band antennas can be as small as 18 inches in
diameter.
Figure 9.
Ku – Band Satellite Antenna
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15. Ka - Band
• Ka-band satellite transmissions occupy the 20 to 30 GHz
frequency range.
• These very high frequency transmissions mean very small
wavelengths and very small diameter receiving
antennas.
Figure 10.
Ka – Band Satellite Antenna
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16. Satellite Orbits
• Satellites travels around the Earth in different orbits.
Figure 11. Satellite Orbits
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17. Geocentric Orbits
A Geocentric orbit involves any object orbiting the
Earth, such as the Moon or artificial satellites.
Figure 12.
Geocentric Orbits
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18. Types of Geocentric
Orbits
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LEO (Low Earth Orbit)
MEO (Medium Earth Orbit)
GSO (Geo Synchronous Orbit)
GEO (Geostationary Earth Orbit)
HEO (Higher Earth Orbit)
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19. Types of Geocentric
Orbits Cont..
Figure 13. Satellite orbits
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20. Low Earth Orbit (LEO)
Satellite Systems
• A low Earth orbit (LEO) is an orbit with an altitude
between 160 kilometers and 2,000 kilometers.
• At 160 km, one revolution takes approximately 90
minutes, and the circular orbital speed is 8,000
meters per second (26,000 ft/s).
• The majority of artificial satellites, have been in LEO.
• Earth observation satellites and spy satellites use
LEO as they are able to see the surface of the Earth
more clearly as they are not so far away.
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21. LEO Cont..
Advantages:
• better signal strength
• Short propagation delays (10 – 15 msec)
• less of a time delay, which makes it better for point to
point communication
• Low transmission power required
• Low price for satellite and equipment
Disadvantages:
• A network of LEO satellites is needed, which can be
costly
• Small coverage spot
• High system complexity
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22. Medium Earth Orbit
(MEO) Satellite Systems
• MEO, sometimes called Intermediate Circular Orbit
(ICO), is the region of space around the Earth
above LEO (altitude of 2,000 kilometers) and below
geostationary orbit (altitude of 35,786 kilometres).
• The most common use for satellites in this region is
for navigation, communication, and space
environment science.
• The most common altitude is approximately 20,200
kilometres (12,552 mi)), which yields an orbital
period of 12 hours, as used, for example, by the
Global Positioning System (GPS).
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23. MEO Cont..
Advantages:
• MEO satellites have a larger coverage area than
LEO satellites.
• fewer satellites are needed in a MEO network than
a LEO network.
Disadvantages:
• A MEO satellite’s distance gives it a longer time
delay and weaker signal than a LEO satellite,
though not as bad as a GEO satellite.
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24. Geo-Synchronous Orbit
(GSO) Satellite Systems
• A geosynchronous orbit (GSO) is an orbit around the
Earth with an orbital period of one sidereal day
(approximately 23 hours 56 minutes and 4 seconds),
matching the Earth's sidereal rotation period.
• When an object is in a geosynchronous orbit it means
that it is traveling around the Earth at the same speed
that the Earth is rotating.
• To someone on the Earth, the object will always appear
in the same region in the sky but it might move slightly
north or south.
• Sidereal day: The time for one complete rotation of the
earth relative to a particular star, about 4 minutes shorter
than a mean solar day.
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25. Geostationary Earth Orbit
(GEO) Satellite Systems
• A geostationary orbit is a special type of
geosynchronous orbit.
• When an object is in geostationary orbit, it is orbiting at
the same speed as the Earth rotates, but it orbits around
the equator.
• From the Earth’s surface, an object in a geostationary
orbit looks like it is not moving at all.
• GEO is a circular orbit about 35,786 kilometres (22,236
mi) above the Earth's equator.
• Communications satellites and weather satellites are
often given geostationary orbits, so that the satellite
antennas that communicate with them do not have to
move to track them, but can be pointed permanently at
the position in the sky where they stay.
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26. GEO Cont..
Figure 14. Geostationary Earth Orbit Satellite System
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27. GEO Cont..
Advantages:
• A GEO satellite’s distance from earth gives it a large
coverage area, almost a fourth of the earth’s surface.
• GEO satellites have a 24 hour view of a particular area.
• These factors make it ideal for satellite broadcast and
other multipoint applications.
Disadvantages:
• A GEO satellite’s distance also cause it to have both a
comparatively weak signal and a time delay in the
signal, which is bad for point to point communication.
• GEO satellites, centered above the equator, have
difficulty in broadcasting signals near polar regions
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28. GEO Cont..
• Only 3 satellites in Geostationary orbit can coveer
the entire globe.
Figure 15.
Tri state satellite system
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29. High Earth Orbit (HEO)
Satellite Systems
• A high Earth orbit is a geocentric orbit with an
altitude entirely above that of a geosynchronous
orbit (35,786 kilometres (22,236 mi))
• Not widely used.
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30. Types of Satellites & their
Uses
Astronomy satellites
• An astronomy satellite is basically a really
big telescope floating in space.
• Used for space observation.
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Figure 16. Astronomy Satellite
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31. Types of Satellites & their
Uses Cont..
Atmospheric studies satellites
• Used to study the Earth’s atmosphere.
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Figure 17. Atmospheric
studies Satellite
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32. Types of Satellites & their
Uses Cont..
Communication satellites
• Communications satellites allow radio, television,
and telephone transmissions to be sent live
anywhere in the world.
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Figure 18.
Communication Satellite
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33. Types of Satellites & their
Uses Cont..
Navigation satellites
• Use to determine location of any object.
• The GPS system is the first core element of the satellite
navigation system widely available to civilian users.
Figure 19. Navigation Satellite
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34. Types of Satellites & their
Uses Cont..
Weather satellites
• Used to find out the weather anywhere in the world
any time of the day.
• Weather forecasting is done by using the Weather
Satellites.
Figure 20. Weather Satellite
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35. Conclusion
• Satellites are most widely used in almost every field.
• Today most of the advancement in various
technologies are due to the satellite systems.
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36. References
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http://searchmobilecomputing.techtarget.com/definition/satellite
http://en.wikipedia.org/wiki/Satellite
http://people.bridgewater.edu/~lwilliam/Chapter%2004/sld049.htm
http://www.jisc.ac.uk/whatwedo/themes/network/sat/report3.aspx
http://www.scribd.com/doc/7140701/52/Principal-Satellite-TransmissionBands
https://www.google.com/images
http://www.youtube.com/watch?v=S22u7_Eq26g
http://www.youtube.com/watch?v=m2WrY1GdQ74
http://www.youtube.com/watch?v=xv9dRENgDoc
http://www.youtube.com/watch?v=m2WrY1GdQ74
http://www.williamcraigcook.com/satellite/work.html
http://www.howstuffworks.com/satellite.htm
http://www.satellites.spacesim.org/english/engineer/copy/
http://www.stmary.ws/highschool/physics/97/MHALLETT.HTM
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