There are an astonishing number of satellite networks in existence. The following table focuses on most of the major networks offering or planning voice services in the next year.
Global Star:
n Operational October 1999
n 52 LEO Satellites (1 400km altitude), in eight planes.
n 60 Ground stations planned. One at Hartbeesthoek in North-West.
n Phones: Combined cellular/satellite personal mobiles are likely to sell at about R8 000, with the usual range of other fixed, vehicular and maritime options.
n Costs: Predicted at being under R18/minute. A monthly subscription through Vodacom will be about R250.
n Capacity: Data services will be available first quarter 2000, at 9 600bps.
n Coverage: Land masses and 200km of ocean adjacent to land (from which 70% of ocean voice traffic is generated). No mid-Atlantic or polar calls, though.
ICO:
n Speed: ICO will use 10 MEO satellites at an altitude of 10 000km, in two planes. At that altitude, there is likely to be some lag, and data services may be slightly complicated.
n Reliability: ICO’s relatively high orbits should mean minimal handover problems. However, since there are fewer satellites in the network, ICO may have problems supporting you in difficult terrain. Most of the time, though, you should be in sight of at least two, and up to four, satellites. The ICO satellites have a 12- year lifespan.
n Capacity: Data capacity services will be offered at 9 600bps. Each of the 12 satellites will be able to handle 4 500 simultaneous calls, which means 54 000 simultaneous calls for the network.
n Costs: To be determined, but lower costs than are currently on offer are promised.
n Coverage: ICO will cover all the world’s land masses, and most of the oceans.
n Phones: ICO promises a range of phones the size of current GSM cellular phones, from NEC, Panasonic, Mitsubishi and Samsung, costing around $1 000 each. Dual mode or satellite-only phones will be available. Vodacom are in discussion with ICO over possibly becoming agents for their services.
Iridium:
n Speed: Iridium satellites are just 780km up, so latency should be minimal.
n Reliability: Horizon-to-horizon time is 10 minutes. Iridium satellites are currently expected to expire in five years, according to Wired.
n Capacity: No data services at present, and will be an unbelievably limited 2 400bps when introduced later this year.
n Cost: MTN costs between R17 and R75 a minute. Calls from Telkom, currently R83 a minute.
n Coverage: The Iridium network has over 60 satellites orbiting north-south in 11 planes, with six satellites in each plane. The highly focused spot beams are 20km wide, meaning coverage can be highly country-specific, depending on how comprehensive Iridium licence agreements are. Parts of the oceans will be excluded.
n Phones: Motorola dual handset, about $3 469; Kyocera satellite only handset, about $3 150; and Kyocera dual handset, about $3 495. Phones weigh around 400g to 500g.
Inmarsat:
n Speed: Four geosynchronous satellites at 36 000km.
n Reliability: Because geosynchronous satellites move with the Earth, maintaining the same position in the sky above you, there are no problems with “handover” of calls from one satellite to the next.
n Capacity: Data at 2 400bps in current STN Atlas 2000 P terminal. A new Mini-M terminal should soon be able to provide 9 600bps data services. Inmarsat B-terminal (weighing 25kg and the size of a suitcase) offers 64 000bps. The Inmarsat B-terminal is used by TV crews transmitting video signals, and fits seamlessly into Earth- bound high-speed data links.
n Cost: $2 or $3 a minute. Satphone to satphone calls are more expensive.
n Coverage: The large footprints of the four geosynchronous Inmarsat satellites make coverage almost global, excluding only the north and south poles. But the limited number of land Earth stations, around 15, means that use of the terrestrial network to get calls to places is extensive, and so rather pricey.
n Phones: The recommended STN Atlas phone (Mini-M-terminal), which with waterproof detachable antenna and battery pack is around the size of a small notebook computer, comes at a cost of around R20 000 (down from R60 000 when it was introduced in February 1997). The phone does need to be aimed before it can be used, unlike later-generation handsets.