Satellite communications systems transmit signals in the gigahertz range – billions of cycles per second. The satellite must be placed in a geosynchronous orbit, 22300 miles above the earth’s surface, so it revolves once a day with earth. To an observer, it appears to be fixed over one region at all times. A satellite is a solar-powered electronic device that has up to 100 transponders (a transponder is a small, specialized radio) that receive, amplify, and retransmit signals; the satellite acts as a relay station between satellite transmission stations on the ground (called earth stations).
Although establishing satellite systems is costly (owing to the cost of a satellite and the problems associated with getting it into orbit above the earth’s surface and compensating for failures), satellite communications systems have become the most popular and cost-effective method for moving large quantities of data over long distances. The primary advantage of satellite communications is the vast area that can be covered by a single satellite. Companies must lease satellite communications time from suppliers such as Intelsat, Comsat, Inmarsat, Utelsat, and Telstar (AT&T), Large companies that have offices around the world benefit the most from satellite communications.