>>How is that data transferred to someone with only a satellite dish, not using a phone? Doesn't the internet feed have to go through space to get to people who only have dishes? Isn't that the whole concern, here? <<
Depends...
The Hughes system which we have been talking about here requires a phone line. You send data via phone, and receive data via satellite. The technical and cost advantage of this system is that the satellites are cheaper, they only need to listen to a single master transmitter who's signal they then rebroadcast. Another key point is that they only need a single satellite per hemisphere (maybe 4 for global coverage?), because they can park it in a high geo stationary orbit, and give it a powerful transmitter.
The Iridium and ORBCOMM systems (which are currently operational) are both two-way systems, you send and receive to the satellites through a conventional whip antenna (not a dish). Some of the problems with both of these systems are:
a) speed: both of them max out at something like 4800 baud, ok for email, but not for surfing.
b) satellite complexity: they have to listen for lots of weak signals and relay them back to home base.
c) number of satellites: because they need to be able to hear your weak signal the satellites need to be a lot closer to the ground, and they need a lot more satellites for global coverage (ORBCOMM has 28 satellites, and Iridium has 66).
The Teledesic system is planning to be able to deliver high speed connections (T-1+) by putting up more satellites (288) in even lower orbits (shorter distance = better/faster signal quality). Unfortunately this isn't expected to be operational until 2003, and it's privately held.
Cheers-
-EAB |
