Chapter 13: Satellite Communication Systems

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Ever since the first communication satellite was launched in 1962 by the United States, satellites have been used extensively for communications. In this chapter, we will study the various applications of satellites, frequency bands in which the satellite communication systems operate, and the multiple access techniques used in satellite communication systems. We also will study the architecture of a representative communication system that uses satellite as the transmission medium.

13.1 APPLICATIONS OF SATELLITES

Satellites are used for a variety of applications such as these:

• Astronomy

• Atmospheric studies

• Communication

• Navigation

• Remote sensing

• Search and rescue operations

• Space exploration

• Surveillance

• Weather monitoring

In communications, satellites are used for broadcasting, providing trunks between switches of telephone networks, providing telephone facilities for remote and rural areas, land mobile communications, marine communication, and many other uses. Many corporate networks use satellite communication for their interoffice communication.

Satellites also are used to send location information to people on the move (on the earth, in aircraft, or underwater). Global Positioning System (GPS) uses 24 satellites that continuously broadcast their positional parameters. The users have GPS receivers. The GPS receiver calculates its own positional parameters (longitude, latitude, and altitude) based on the data received from the satellites. We will discuss the details of GPS in Chapter 32, "Global Positioning System".

Surveillance satellites are fitted with video cameras. These satellites continuously monitor the enemy's territory and send video data to a ground station. Surveillance satellites are used by many countries to keep track of the activities of other countries.

Satellites are used for a variety of applications such as communication, broadcasting, surveillance, navigation, weather monitoring, atmospheric studies, remote sensing, and space exploration.

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