The IRIDIUM communications system

The IRIDIUM communications system is to be a global, digital, satellite-based, personal communications system primarily intended to provide low-density, portable service via hand-held subscriber units, using low-profile antennas. Calls could be made and received anywhere in the world with a personal, pocket-size, portable unit. A constellation of small satellites are to be internetted to form the network´s backbone. Small, battery-powered, cellular-telephone-like user units are to communicate directly with the satellites. Terrestrial gateways are to interface the satellite network with the Public Switched Telephone Network. The system is intended to complement the terrestrial telephone network in densely populated areas by providing a similar service everywhere else in the world. Brief descriptions are given of the components of IRIDIUM: the G6-satellite constellation, the system control facility, the gateways, the subscriber units, and the communication networks.<>