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PUBLIC SATELLITE NETWORKS Satellites have been carrying communications since the early 1960s, serving as relays for voice, video, or data. They have long been dominated by the military and, in their direct broadcast form, by large television communications companies. In 1989 the Gartner Group believed that the mobile satellite industry will be one of the great growth markets of the next decade surpassing cellular telephones and digital paging, and in the same league as personal computers. 1 Gartner believed that there would be 800,000 satellite data terminals installed by 1993, growing to 2 million by 1995. A flood of vendors rushed toward this. | The Wireless Data Haadbaak Fourth Edition. James F. DeRose Copyright 1999 John Wiley Sons Inc. ISBNs 0-471-31651-2 Hardback 0-471-22458-8 Electronic 6 PUBLIC SATELLITE NETWORKS 6.1 INTRODUCTION Satellites have been carrying communications since the early 1960s serving as relays for voice video or data. They have long been dominated by the military and in their direct broadcast form by large television communications companies. In 1989 the Gartner Group believed that the mobile satellite industry will be one of the great growth markets of the next decade surpassing cellular telephones and digital paging and in the same league as personal computers. 1 Gartner believed that there would be 800 000 satellite data terminals installed by 1993 growing to 2 million by 1995. A flood of vendors rushed toward this magnificent opportunity many of which were never seen again. After this debacle intense activity began for new classes of satellites mostly for voice communications. The successful September 1993 deployment of NASA s Advanced Communications Technology Satellite ACTS showed the potential value of the new designs on-board processors spot beams and Ka band operation to penetrate rain clouds. Hundreds of competitive launches are scheduled for the next few years. By some tallies at least 1300 satellites are scheduled to be launched into the Ka band alone.2 Iridium was scheduled to be operational in September 1998. Broadband capability will not be operational until 2002 and includes Craig McCaw s and Bill Gates s Teledesic. The enormous broadband capacity is certain to revolutionize some forms of communications. Some market research firms now estimate thatjust the near-term satellite business could triple to 29 billion per year by 2000. But we have heard predictions like that before. 70 6.2 GEOSTATIONARY SATELLITE SYSTEMS 71 6.2 GEOSTATIONARY SATELLITE SYSTEMS 6.2.1 GEOS Overview Geostationary satellites GEOS operate at roughly 22 300 miles altitude above the equator where
