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Satellite Phones and their Use on Ship.

written by: Raunekk • edited by: KennethSleight • updated: 2/11/2012

How can a ship stay in touch with shore once it's miles away from the land?A continuous contact with the shore is important to prevent accidents and emergency situations. Satellite phones are the only mode of communication. Let's have a look as to how do they work and what are their applications.

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    Introduction

    Communicating with people when on land is not a difficult task. You just punch a number in your cell phone and you are connected to the desired person. The service is easy, fast and reliable. Cell phones have stipulated towers to send and receive signals upto an approximate range of 1-5 miles. But what when we are at a place where there are no cell phone towers? Satellite phone in an answer for a " No tower" communication system. A satellite phone directly connects to the satellite without the use of any mediator. You can make a call from any place on the surface of earth , provided you are under a clear and unobstructed sky. So how do satellite phones work on board a ship? Let's find out.

    satellite phone  

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    Which satellite the phones use?

    A satellite phone like any other cell phone uses radio waves for the transfer of signals. There are many satellite phone service providers but the quality of service depends on the type of satellite they use. The two main types of satellites are :

    • Low Earth Orbit satellites(LEO)
    • Geosynchronous satellites

    The height of a LEO satellite, orbiting the earth varies greatly. Some satellites are polar, which means they reach both the poles of the earth while orbiting. Satellites that are not polar do not reach the Antarctic and the Arctic regions. The quality of service a satellite phone provides depends on the height of its orbit. If the phone is using a satellite of a lower height, the coverage area provided to it will be less. This means that the satellite at lower heights have lesser coverage area as compared to the higher ones. LEO satellite phones rarely face delay in connection but have lesser mobility due to smaller coverage area.leo  

    Geosynchronous satellites are located at higher orbits, at an approximate height 22,300 miles above the earth's surface. These satellites move at the same rate as that of the earth. As they are located at higher orbits, they have a very large coverage area. One satellite can cover around one-third of the earth's surface. The phones using these satellites generally have long antennas,facing the direction of the satellite and often face delay in connection. A clear and unobstructed sky is a must.

    GEO   There are also Iridium phones that use non-directional antennas. This means that the phones antenna needn't be pointing in a particular direction.

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    How do they work?

    When a crew member makes a call from a satellite phone the signal goes directly to the satellite of that service provider. The call is processed by the satellite and is then sent to the earth through a gateway. The gateway directs the call through the regular landline or the local cell phone service providers.

    If a person from the ship wants to make a call to an another satellite phone, the signal is sent to the satellite and is relayed to the receiver phone without the help of any gateway. Thus there is no inter mediator in a satellite to satellite phone.

    The only issue regarding the usage of a satellite phone is that they have long antennas. The antennas should face the satellite whenever the call is being made. A satellite call will face interruption and delay if the call is made from inside of a building or the sky is not unobstructed. As the satellite phones do not use any land infrastructure and also due to their capability to provide uninterrupted services, the call charges are very high compared to that of a normal cell phone. Also the handsets are large in size and heavy in weight.

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    Applications

    A satellite phone is a boon for a ship and its crew members. It's the only and the most effective source of communication on ship. Satellite phones have made a life saving difference during emergency times. Weather conditions are often unpredictable at sea and satellite phones are used to caution a ship in case of storm, rogue waves or any sudden change in the weather condition.

    Satellite phones are also used by the ship personnel to connect to the nearest shore in case of any emergency situation. Not only that, satellite are used for business purposes too. It is an important tool to remain in contact with the clients of the next port of call. It also provides data line to send and receive business information and transactional documents.

    In case of natural disaster such as Hurricane, Floods or Earthquakes, land based cellular towers are often destroyed, cutting off the communication with the affected ares. It is during such conditions that satellite telephony becomes the only mode of communication for beckoning help.

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    References

    http://www.satellitephones.us/phones.htm

    How do satellite phones work? By Rex Strong

    Image credits

    http://njlawman.com/images/Satellite-Phone.jpg

    http://www2.plymouth.ac.uk/distancelearning/satellite.html