Satellite Communications Overview
In the 50 years that followed the first satellite launches of the late 1950s and early 1960s, the diversity of satellite services has expanded enormously. Today, there are direct broadcast radio and television services to the home and even to mobile receivers. There are mobile satellite services to airplanes, ships at sea, and even hand-held transceivers. There are so-called fixed satellite services to earth stations of various sizes down to so-called very small antenna terminals (VSATs), microterminals, and even ultra small aperture terminals that can be located on desktops. There are data relay satellites and business to business satellite systems. The age of the Internet and data networking has certainly served to add to the diversity of satellite services. Technology innovation has also led to the growth and development of satellite communications services. Lower cost launch arrangements and development of earth station technology and particularly application specific integrated circuits have been key to driving down the cost and size of ground antennas and transceivers. The development of three axis body stabilized spacecraft, better solar cells and batteries, and more effective on-board antenna systems and on-board switching among multi-beam antennas have also furthered the cause. Finally, the development of not only bigger and better satellites but the evolution of satellite systems design and network architecture that allowed networks to be deployed in different types of orbits and network constellations has been part of this on-going evolution.
The latest iterations of satellite design have led to almost opposite extremes. On one hand there are large, sophisticated multi-ton satellites, known as high throughput satellites, deployed in traditional geosynchronous orbit locations. On the other hand, there are also small but capable satellites in low to medium earth orbit constellations. These new satellite networks are being designed with more and more mass-produced satellites – up to a thousand or more in a single system – to increase network capacity by means of deploying more and more satellites in lower orbit.
This chapter provides a general introduction to all of these changes and an overview to the entire field. Changes to satellite communication networks over the past half century have come not only in services and technology but also in regulation, standards, frequency allocations, economics, as well as the global reach and impact of satellites on the entire scope of human society.
KeywordsBroadcast satellite service (BSS) Data relay satellites Fixed satellite service (FSS) Geosynchronous earth orbit (GEO) International Telecommunication Union (ITU) Intersatellite link (ISL) Low earth orbit (LEO) Mobile satellite service (MSS) Satellite constellations Store and forward satellite service
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