Satellite Communications

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Satellite Communications

• COE 341 Term Paper

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Groupe Members
Aref Mohammad Al-Amri
Ahmad Abdulrahman Al-Gahtani
Ahmad Abdullah Al-Aloula
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Topics of Presentation
Intro
Lunching
Applications
Satellites
How itworks
Frequency Bands
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What are Communication Satellites?

• A satellite is an object that orbits another
  large object like planet.
• A communication satellite is a staion in space
  that is used for telecommuncation, radio and
  television signals.
• The first satellite with radio transmitter was
  in 1957.

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Geostationary orbits

• What are them? Geostationary orbits is fixed
  position to an earth-based observer.
• When was the first use? The first truly
  geostationary sateliite was the SYNCOM3 in 1964.
• Why they are important in communications? -
  The antennas in the ground dont need equipment
  to track the satellite. - Lower cost
  complixity.
• Disadvantages? - Not always suitable for
  providing services at high latitudes. -
  Molniya satellite was introduced as a solution.

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Lunching Satellites

• How does a satellite stay in its orbit?

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Frequency Bands

• Three common bands
• C-Band.
• KU-Band.
• KA-Band.
• Most common are C-Band KU-Band.
• C-Band occupy 4 to 8 GHz frequency- Low
  frequency.- Large antenna (2-3 meters).
• KU-Band occupy 11 to 17 GHz- Large frequency.-
  Small antenna (18-inches!)

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How Does a Satellite Work?

• Consider the light bulb example

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Applications

• Telephony - Fixed pointslt earth stationgt
  Satellitegt earth stationgt fixed points.
• Televesion Radio - e.g. Direct broadcast
  satellite (DBS) Fixed service satellite (FFS).
  
• Mobile satellite technology - Special
  antenna called mobile satellite antenna. -
  No matter where or how this antenna is mounted on.

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Applications

• Amateur radio - Access to OSCAR satellite.
  - Low earth orbits.
• Internet - High Speed. - Useful for far
  away places.
• Military - Uses geostationary satellites.
  - Example The Defense Satellite Communications
  System (DSCS).

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Disadvantages

• The antenna noise due to energy - Unwanted
  radiation sources (stars galaxies - etc).
  - Worsen S/N ratio.
• Atmosphere behaves as a resistive medium -
  Supplies noise power to the antenna.
• Meteors - Have to be programmed to avoid any
  rock or any harmful thing. - Rules of
  orbits.
• Expensive - only for governments or large
  organizations.

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In Conclusion
Satellites remain the best utilization used for
communications due to their speed and other
advantages mentioned in this presentation.
Thanks for Listening