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A '''satellite modem''' or '''satmodem''' is a [[modem]] used to establish [[data transfer]]s using a [[communications satellite]] as a [[relay]]. A satellite modem's main function is to transform an input bitstream to a radio signal and vice versa.
There are some devices that include only a demodulator (and no modulator, thus only allowing data to be downloaded by satellite) that are also referred to as "satellite modems."
== Satellite link ==
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Similarly, a signal received from a satellite is firstly [[downconverter|downconverted]] (this is done by a [[Low-noise block converter]] - LNB), then demodulated by a modem, and at last handled by data terminal equipment. The LNB is usually powered by the modem through the signal cable with 13 or 18 V [[Direct current|DC]].
== Features ==
The main functions of a satellite modem are modulation and demodulation. Satellite communication standards also define [[error correction]] codes and [[framing (World Wide Web)|framing]] formats.
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* ''Embedded Distant-end Monitor and Control'' (EDMAC), allowing to control the distant-end modem;
* ''Automatic Uplink Power Control'' (AUPC), that is, adjusting the output power to maintain a constant [[signal-to-noise ratio|signal to noise]] ratio at the remote end;
* [[Drop and insert]] feature for a [[multiplexing|multiplexed]] stream, allowing to replace some channels in it.
== Internal structure ==
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== Applications ==
[[File:NovelSat Satellite Modem NS3000.png|thumb|The NS3000 Satellite Modem modulates and demodulates data and video signals transmitted via satellite.]]
[[File:ASTRA2Connect Modem front.jpg|thumb|right|The "
Satellite modems are often used for home [[satellite internet|internet access]].
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== See also ==
* [[Communications satellite]]
* [[Data collection satellite]]
* [[Al Yah Satellite Communications|Yahsat]]
* [[Intelsat]]
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== External links ==
{{Satcomm}}
▲# ITU Radio Regulations, Section IV. Radio Stations and Systems – Article 1.113, definition: ''satellite link [http://www.itu.int/ International Telecommunication Union (ITU)]''
▲# Talal, M. (1997). ''Modem design for digital satellite communications'' (Doctoral dissertation, Loughborough University). https://core.ac.uk/download/pdf/288390356.pdf
[[Category:Satellite broadcasting]]
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