Monday, February 16, 2009

Satellite phone

A satellite telephone, satellite phone, or satphone is a type of mobile phone that connects to orbiting satellites instead of terrestrial cell sites. Depending on the architecture of a particular system, coverage may include the entire Earth, or only specific regions.
 
Satellite phone (Inmarsat)

The mobile equipment, also known as a terminal, varies widely. Early satellite phone handsets had a size and weight comparable to that of a late 1980s or early 1990s mobile phone, but usually with a large retractable antenna. More recent satellite phones are similar in size to a regular mobile phone while some prototype satellite phones have no distinguishable difference from an ordinary smartphone[1][2]. Satphones are popular on expeditions into remote areas where terrestrial cellular service is unavailable.

A fixed installation, such as used shipboard, may include large, rugged, rack-mounted electronics, and a steerable microwave antenna on the mast that automatically tracks the overhead satellites. Satellite phones have notoriously poor reception indoors, though it may be possible to get a consistent signal near a window or in the top floor of a building if the roof is sufficiently thin. The phones have connectors for external antennas that are often installed in vehicles and buildings. Some systems also allow for the use of repeaters, much like terrestrial mobile phone systems.

In some countries ruled by oppressive regimes, such as Burma, possession of a satellite phone is illegal[3][4] as their signals will usually bypass local telecoms systems, hindering censorship and wiretapping attempts. In Australia, residents of remote areas may apply for a government subsidy for a satellite phone.[5]

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