Inmarsat uses lower, L-Band frequencies (1.5Ghz), which have wider beam width and are therefore more forgiving on pointing accuracy than higher frequency VSATs. This allows the use of slightly less sophisticated stabilization and lower cost terminals.
The downside is that there is not much bandwidth available at L-Band compared to the the higher frequency C-band and Ku-band and is therefore at a premium. As an analogy, the value of L-Band bandwidth is like city real estate, whereas C and Ku-Band are like country farmland.
Inmarsat provides global coverage (except extreme polar regions) using 3 or 4 dedicated, geostationary satellites to over 200 000 maritime terminals.
The legacy I3 satelites use 4 satellites positioned at:
|IOR||Indian Ocean Region||64.0E|
|AOR-E||Atlantic Ocean Region East||15.5W|
|AOR-W||Atlantic Ocean Region West||53.0W|
|POR||pacific Ocean Region||178.0E|
The new technology Fleet Broadband is covered by three I4 satellites at
|Americas||98o W||N and S America, E. Pacific|
|EMEA||25o E||Europe, Middle East and Africa|
|Asia-Pacific||143.5oE||India, China, Australia, W.Pacific|