An on-ground terminal linked to a spacecraft or satellite by an antenna and associated electronic equipment for the purpose of transmitting or receiving messages, tracking, or control.
A dish antenna, amplifier, and transmitter or receiver used for sending or receiving signals directly to or from communications satellites.
An on-ground radio communication site used for tracking, controlling, or otherwise communicating with spacecraft or satellites.
A ground-based receiving or transmitting/receiving station in a satellite communications system. The counterpart to the earth station is the satellite in orbit, which is the "space station." Earth stations use dish-shaped antennas, the diameters of which can be under two feet for satellite TV to as large as fifty feet for satellite operators. Antennas for space exploration have diameters reaching a hundred feet.Multiplex, Modulate and UpconvertAn earth station is generally made up of a multiplexor, a modem, up and downconverters, a high power amplifier (HPA) and a low noise amplifier (LNA). Almost all transmission to satellites is digital, and the digital data streams are combined in a multiplexor and fed to a modem that modulates a carrier frequency in the 50 to 180 MHz range. An upconverter bumps the carrier into the gigahertz range, which goes to the HPA and dish.Downconvert, Demodulate and DemultiplexFor receiving, the LNA boosts the signals to the downconverter, which lowers the frequency and sends it to the modem. The modem demodulates the carrier, and the digital output goes to the demultiplexing device and then to its destinations. See earth station on board vessel and base station.