Saturday, 21 May 2011

Satellite Phone System

In a lot of the very remote places around the world, satellite phones are becoming more and more popular.  Since these phones do not require cabling, the need for communication in these areas has been covered by the use of these satellite phones.  A lot of these remote areas just do not have the infa structure available to allow for a more traditional land line phone.  Radio frequencies could be considered as well but all the frequencies for radio are for the most part, already occupied with other things.

For communication, satellite phones use what is called low earth orbiting satellites or LEO for short.  The main advantage to using these types of satellites over other types such as geo stationary satellites, is that there is very little latency.  Since low earth orbiting satellites are quite a bit closer to the earth, there is less delay in communication.

Each satellite phone system includes a number of LEO satellites usually called a constellation.  The use of many satellites makes sure that there is always a satellite visible to the phone so that calls can be made or received whenever they are needed.  This ensure that there are never any missed calls or calls that get go through to the person that you are calling.

There are a number of different providers that offer these types of phone services - Iridium and Globalstar are just a couple and there are a number more.  Each of these companies use various technologies to get the service done but in the end, they are mainly all the same.  They all provide the satellite communication service.

A few of these companies use a multiple access method of time division to allow and increased number of calls.  This includes connections that are satellite to satellite and the phones work directly with these satellites.  There are also digital technologies that are used to manage the traffic of calls and sometimes this is called, code division multiple access.

When division multiple access is used, the satellites are used to forward the incoming calls directly to the telephone gateways that exist on the earth.  This way, the call eventually goes through the tradtional land telephone network.

With the different ways this satellite phone technology work, the end result does not change.  The basic thing is that in the end, you get through to who ever you need to talk to!

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