Satellite phone systems are now getting popular because of the need for people to communicate even from the remote corner of the world. Communication is taking new strides of its own and mere cable connections and radio lines are not able to satisfy the growing need for wider coverage.
Satellite phone systems are now necessary, because the cable lines cannot be fixed to all the parts of the earth and the bandwidth of radio frequencies, which connected most of the parts on the surface of the earth, is exhausted. The satellite phone systems include Low Earth Orbiting (LEO) satellites. LEO satellites are preferred to geo stationary satellites because the latter introduces delay. This delay introduced by geo stationary satellite can vary with the distance at which it is placed. The least delay is about 0.5 seconds and this is a major disadvantage of geo stationary satellites so we go in for LEO satellites that have become a part and parcel of the satellite phone systems.
The system of satellite phones include not a single LEO satellite, but a constellation of LEO satellites, this is done because the LEO satellites are placed close to the earth and so they revolve faster than the earth making them invisible at times. So when one satellite is moving out of the horizon, another LEO satellite comes up close by to receive the calls.
The technology implemented by the satellite phones depends on the type of service providers like GlobalStar systems and Iridium systems. Satellite phone systems also include the various techniques used for the transmission of data, be it audio or video signals.
Some companies like the Iridium uses time division multiple access scheme to increase the number of calls that can be attended. It has satellite-to-satellite connections as a part of the phone systems thus handsets work directly with the satellites. Another satellite phones system, the GlobalStar implements new digital technology called code division multiple access and satellites for attending the traffic of calls.
In this system, satellites are used only as relay stations that is, they receive and forward calls to the gateways on the earth and the call reaches the public switched telephone network. Regardless of the technology used, the main aim of the satellite phone systems and service providers is to keep their customers in contact wherever they go.
