About Iridium
Most satellite communication runs through a handful of satellites parked above the equator. That works admirably up to around seventy degrees of latitude and no further, because beyond it the satellite sinks below the horizon. Iridium chose a different model: sixty-six satellites in low orbit, continuously handing over to one another. Wherever you sail, there is always one in view.
For shipping that is the difference between having a connection and not having one on the northern routes and in the far south. The network carries voice and data, and has recently been approved for GMDSS, the global distress and safety service, making it the first genuine alternative to Inmarsat.
On board you see this as a terminal, with a dome antenna on deck and a unit below. Iridium Pilot is the best known of them. The logo on the equipment itself is usually the builder's; Iridium is the network it runs on.
