The little brother in Inmarsat's Fleet family is now complete and ready to go following the launch of Fleet 33's mobile packet data service (MPDS). Fleet 33 is the smallest of the three-system-strong Fleet family. Fleet 77, the first to be rolled out, offers a full voice and data service with global coverage (global, in Inmarsat-speak, meaning coverage of all except the two Polar Regions) and is aimed at the ocean-going merchant marine market. The two smaller options, Fleet 55 and Fleet 33 (the numbers correspond roughly to the diameter of the antenna required), offer global voice coverage, though data coverage is limited to the spot beam area. Spot beam coverage is presently available in all coastal waters and ocean regions in the northern hemisphere, though southern hemisphere ocean coverage is limited. The major difference between Fleet 55 and Fleet 33 is that the former offers 64Kbit/s ISDN data, whereas the latter transfers at 9.6kbit/s.
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