earth station

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earth station

[′ərth ‚stā·shən]
(communications)
A facility with a land-based antenna used to transmit and receive information to and from a communications satellite.

earth station

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 Upconvert
An 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 Demultiplex
For 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.


Earth Station
Earth stations use dish-shaped antennas to transmit and receive microwave signals to and from satellites.







On Board a Ship
Earth stations on board vessels (ESVs) are used to receive TV, make phone calls and access the Internet while traveling near the coast or on the high seas. Encased in a waterproof container, the ESV must be able to track the satellite with great precision. If the ESV deviates by a half a degree, it must shut down transmission immediately in order to not interfere with other satellites. (Image courtesy of Sea Tel Inc., www.seatel.com)
References in periodicals archive ?
Earth stations will allow much faster data speeds, as Ofcom is making available a relatively large amount of high-frequency spectrum for their use.
Thrane & Thrane has installed more than 150 Inmarsat Land Earth Stations to date.
Including the new order Thrane & Thrane has delivered 14 of the 22 Inmarsat-C land earth stations currently in operation.
Comtech Telecommunications Corporation (Nasdaq: CMTL - news) has announced that its Arizona subsidiary, Comtech EF Data Corporation, received a multi-million dollar order for satellite earth station transceivers and modems from Globecomm Systems, Inc (Nasdaq: GCOM), a leading global provider of end-to-end satellite-based communications solutions.
A third RFP will be issued later this year for ten remote rural earth stations, each carrying 12 to 30 circuits to operate with TDM wireless digital access systems.
Earth station electronics are also more mature for C-band micro earth stations and therefore less expensive.
The concept of planning an earth station, simply put, is to transmit and receive signals to and from specific satellites while avoiding interfering with, or receiving signal-degrading interference from, another communications facility.
During the day-long session the FCC took up the issue of individual carriers owning and operating US earth stations linked to Intelsat's global communications satellite system, asking for comments on the proposal (Docket 83-540).
Many considerations associated with receive-only earth stations are applicable to transmit/receive earth stations.