Introduction
          In general terms, a satellite is a smaller object that revolves 
           around a larger object in space. Ex. moon is a natural satellite 
           of earth.
          Communication refers to the exchange (sharing) of 
           information between two or more entities, through any 
           medium or channel.
          If the communication takes place between any two earth 
           stations through a satellite,  satellite communication
          It is helpful in telecommunications, radio and television along 
           with internet applications.
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    Need of Satellite 
    Communication
          •   In the satellite communication, satellites provide 
              communication for long distances, which is well beyond 
              the line of sight. 
             •   Ground wave and Sky wave propagation: The maximum hop or the 
                 station distance is limited to 1500KM
             •   Satellite communication overcomes this limitation
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   Satellite Network 
       • A satellite network is a combination of nodes, some of which 
         are satellites, that provides communication from one point on 
         the Earth to another. 
       • A node in the network can be a satellite, an Earth station, or an 
         end-user terminal or telephone
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   Communication Satellite 
        •  Communications satellite is an artificial satellite stationed 
           in space for the purpose of telecommunications. 
        •  It is nothing but a microwave repeater station in space.
        •  A repeater is a circuit, which increases the strength of the 
           received signal and then transmits it. But, this repeater 
           works as a transponder. 
        •  That means, it changes the frequency band of the 
           transmitted signal from the received one. 
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        Uplink and Downlink 
        Channels and  Frequency
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