Satellite communication

Satellite communication uses artificial satellites to relay signals between distant locations. Satellites receive, amplify or process, and retransmit radio signals across areas beyond the reach of direct terrestrial links.

Communications satellite: An artificial satellite designed to receive and transmit communications signals. It is the orbital relay at the center of each satellite link.
Satellite television: Television distribution in which satellites relay broadcast signals to receiving dishes or cable systems. It is a major one-to-many use of satellite communication.
Radio propagation: The behavior of radio waves as they travel through space and interacting materials. Satellite signals encounter distance-related loss, atmospheric effects, and obstacles during propagation.
Low Earth orbit: An orbit relatively close to Earth, commonly used by satellites below about 2,000 kilometers altitude. LEO satellites reduce signal delay but move quickly across the sky, unlike geostationary satellites.
Telstar 1: A 1962 communications satellite that relayed the first live television images across the Atlantic. Its demonstrations made transatlantic satellite broadcasting visible to the public.
Transponder: A device that receives a signal, shifts or processes its frequency, and retransmits it. Traditional satellites use transponders to relay signals between uplink and downlink frequencies.
Satellite internet access: Internet connectivity delivered through communication links involving satellites and user terminals. It extends broadband service to locations beyond practical wired or cellular coverage.
Radio spectrum: The range of electromagnetic frequencies used for radio transmission and reception. Satellite services depend on allocated frequency bands to separate links and manage interference.
Medium Earth orbit: An Earth orbit between low Earth orbit and geostationary orbit in altitude. MEO offers an intermediate balance of coverage, satellite count, and latency.
Intelsat: An intergovernmental organization established to operate a global commercial satellite communications system. Its network helped make international satellite telephone and television services widely available.

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