Definition of:communications satellite
communications satellite

A radio relay station in orbit above the earth that receives, amplifies and redirects analog and digital signals contained within a carrier frequency. There are three kinds. Geostationary (GEO) satellites are in orbit 22,282 miles above the earth and rotate with the earth, thus appearing stationary. The downlink from GEOs back to earth can be localized into small areas or cover as much as a third of the earth's surface.

LEOs and MEOs
Low-earth orbit (LEO) satellites reside no more than 1,000 miles above the earth and revolve around the globe every couple of hours. They are only in view for a few minutes, and multiple LEOs are required to maintain continuous coverage. Medium-earth orbit (MEO) satellites are in the middle, taking about six hours to orbit the earth and in view for a couple of hours. See GEO, LEO and MEO.

Fixed (FSS) and Mobile (MSS) Satellite Services
Delivery from a communications satellite may be to stationary terminals such as rooftop dishes (FSS) or to mobile terminals in cars, planes and ships (MSS). See satellite bands, Teledesic, Iridium, DSS, FSS, DirecPC and bent pipe architecture.

Communications Satellite
There are hundreds of commercial communications satellites in orbit providing services for both industry and consumers.