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Global Satellite Communications
By Editor | February 4, 2008
Global satellite communications are made possible by several kinds of communications satellites like geostationary satellites, low earth orbit (LEO) satellites and Molniya satellites. These are artificial satellites which have been put up in space for telecommunication purposes. Satellite communications enable two different kinds of services. One, fixed point to point. This is similar to someone calling up from a landline number to another landline number. In fixed point to point services, as the name implies, both the points of telecommunication are fixed or stationary. In such cases, satellite communications provide a parallel to fibre optic submarine communication cables and though the latter is cheaper, the former continues to be used in places where it is not practical or possible to lay fibre optic submarine communication cables. Some islands like St.Helena, Ascension Island and the Pacific islands depend on global satellite communications as fibre optic submarine communication cables have not been laid over there. Also, the polar caps are other instances of places which depend on global satellite communications. Two, mobile satellite communications. In mobile satellite communications, one or both the points is/are mobile. For instance, the mobile point(s) may be a ship, a moving vehicle or an aeroplane. Also, unlike conventional mobile phones, satellite phones have unlimited coverage, as in, they provide global communication by their very nature.
Global communications satellites form a constellation or a system of interlinked satellites. For geostationary satellites, 4 to 6 satellites are enough to cover the whole surface of the earth. For highly elliptic and medium earth orbit satellite systems, more number of satellites is used. For low earth orbit satellite constellations, about 24 would be required at least. Iridium, the global satellite company has 66 satellites in their constellation. Molniya satellites are useful for telecommunication near the poles as geostationary satellites revolve around the equator. Molniya satellites are inclined for optimum use at the poles and are primarily used for telephony and TV services over Russia.
Global satellite communications provide not only telephone services but also internet and other telecommunication related services like television services. Satellite broadband and satellite television are extremely popular nowadays. Satellite radio is also provided by global satellite telecommunications. Then there are the Orbital Satellite Carrying Amateur Radio (OSCAR) satellites which are meant specifically for amateur radio operators.
These are some of the important services that global satellite communications provide but the most important and service remains the satellite phone. With several satellite phone operators like Iridium, Globastar and Inmarsat, it is a competitive field. Satellite phones are especially useful for frequent fliers, those working in remote locations like mountains, forests or near the polar caps.
Global satellite communications make use of satellites in space rather than physical cables connecting the two points. Therefore, with satellite communication, it is possible to connect any two points on earth. With a large portion of services being carried out through the internet and telecommunications playing a major role in our daily lives, global satellite communications are important means of communication in the modern world.
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