What Are Communication Satellites?

Satellites were developed to reduce the cost of long distance transmission via terrestrial microwave repeater stations and to provide a cheaper and better overseas communications medium than undersea cable. Many older satellite maintain geosynchronous orbits 22,300 miles above the earth. Geosynchronous means that, because the satellite travel at the same speed as the earth's rotation, they appear to remain stationary over a given spot on the globe. Such satellites are so far above the surface of the earth that it takes only three of them to blanket the planet with signals. Not all satellites travel thousands of miles above the earth.

Two relatively new satellite projects that use a low-earth orbit(LEO) strategy are IRIDIUM and telexes. LEO satellites circle the globe at an altitude of less than 500 feet. They are cheaper to build, and because of their lower orbits, they provide faster ,message transmission than traditional satellite. Both communications satellites and terrestrial microwave stations work best when they transmit large amounts of data one way at a time. Thus, they are ideal for applications such as television and radio broadcasting and getting information from the internet