Definition: 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. Based on their distance from the earth, there are three categories: GEO, LEO and MEO.

Geostationary (GEO) satellites are in orbit 22,282 miles above the earth. Because they rotate with the earth, they appear motionless to an observer on the ground. The GEO downlink to earth can be localized into small areas or cover as much as a third of the globe's surface. Low-earth orbit (LEO) and medium-earth orbit (MEO) satellites are much closer to the ground, and they revolve around the planet. See GEO, LEO and MEO.

Fixed and Mobile Satellite Services (FSS/MSS)
Delivery from a communications satellite may be to stationary terminals such as rooftop dishes (see FSS) or to mobile terminals in cars, planes and ships (see MSS). See satellite Internet, satellite frequency bands, space pollution and bent pipe architecture.

Communications Satellite

There are thousands of communications satellites in orbit providing private channels between business and government facilities as well as telephony, radio, TV and access to the Internet for the general public (see satellite Internet).