Inmarsat Networks
Inmarsat is the pioneer of global mobile satellite communications.
Today it stands at the forefront of 3G wireless telephony, capitalizing on almost a quarter of a century's experience to deliver broadband communications solutions to enterprise, maritime and aeronautical users around the globe.
Inmarsat operates a constellation of geostationary satellites that extend mobile phone, fax and data communications to every part of the world, except the poles.
End-users can dial into the international telephone network and send data over the Internet at any time, simply by connecting to an Inmarsat satellite.
They include ship owners and managers, TV broadcasters, international aid workers, national governments, commercial airlines, banks and other financial institutions, and many others.
Inmarsat came into being as an IGO in 1979 to provide global safety and other communications for the maritime community. Starting with a customer base of 900 ships in the early 1980s, it then grew rapidly to offer similar services to other users on land and in the air, until in 1999 it became the first IGO to be transformed into a private company.
It now supports links for phone, fax and data communications to more than 287,000 ship, vehicle, aircraft and other mobile users.
The new Inmarsat I-4 satellites
started entering service in 2006. They are forming the backbone of Inmarsat's Broadband Global Area Network (BGAN) services, offering phone and mobile data communications at up to 492kbps for Internet access, mobile multimedia and many other advanced applications.
Inmarsat I-4: Gateway to Broadband
The launch of Inmarsat's next-generation satellite system has begun - two of three Inmarsat-4 (I-4) satellites are now in commercial operation in the Indian and Atlantic Ocean Regions.
The fourth-generation I-4 spacecraft are among the largest commercial communications satellites ever launched. They are replacing their highly successful predecessors (the Inmarsat-2 and Inmarsat-3 spacecraft) as the pillars of Inmarsat's new Broadband Global Area Network (BGAN) services.
Together they will usher in a new era, which we call 'Broadband for a Mobile Planet™', delivering simultaneous voice and data at speeds of about half a megabit per second.
Each I-4 is a veritable powerhouse compared with the Inmarsat-3 spacecraft, offering:
* Greater call capacity than all five I-3s put together
* 60 times more power than any one of its predecessors
* 12 times greater efficiency in its use of radio spectrum
* 16 times the capacity
* 25 times the receiver sensitivity.
The Inmarsat-4s, like their predecessors, are equipped with a single global beam that covers up to one-third of the Earth's surface, apart from the poles.
Each satellite also generates 19 wide spot beams that provide continuous coverage across the same region for Inmarsat's existing high-end services, including Fleet F77 128kbps, Fleet F55 and F33, and maritime mini-M.
New to the I-4s are an additional 228 narrow spot beams, designed to form the backbone of Inmarsat's future broadband services, including the Broadband Global Area Network (BGAN), which has launched as of the end of 2005.
BGAN delivers Internet and intranet content and solutions, video-on-demand, videoconferencing, fax, e-mail, phone and LAN access at speeds of up to 492kbps.
Together the I-4 beams will service about 85 per cent of the world's landmass, covering approximately 98 per cent of the global population.
In-orbit operations
The Inmarsat satellites are positioned in geostationary orbit. This means they follow a circular orbit in the plane of the Equator at a height of 35,600km, so they appear stationary relative to a point on the Earth's surface.
A call from an Inmarsat mobile terminal goes directly to the satellite overhead, which routes it back down to a gateway on the ground called a land earth station (LES). From there the call is passed into the public switched telephone network (PSTN).
