I think your remark about Motorola are not only untrue but out of place in
this forum.
bill schmidt
-----Original Message-----
From: Peter Sterling [mailto:[email protected]]
Sent: Tuesday, October 03, 2000 12:22 PM
To: Smith JR, Harry E
Cc: [email protected]
Subject: Re: Moving Targets
Harry
The thing that killed Teledesic was a company called Motorola and a grossly
overpriced, no-bandwidth project called Iridium.
Your cell phone hands-off as you move around with no problem and a LEO
system can do the same with no technical problems.
The LEO satellite is in view of any one spot for around 10 minutes so the
hand-off issue is probably less than for a terrestrial system. The primary
advantage of LEO is the lower power requirements to connect, hence smaller
antenna possibilities. Also it costs one quarter the price per lb to put a
satellite into LEO than GEO. Add the power advantage to the cost advantage
and a global broadband LEO system can give 400% increase in available
bandwidth per $ over a global GEO system, and there's no 1/4 second delay
associated with LEO.
Despite what the GEO crowd believes, because of the latency issue, power and
LEO cost advantage, its probable that ten years from now LEO systems will
make up half of the satcom market.
Teledesic currently has a GEO-Type fixed LEO architecture with stupendous
capital costs and high technical risks, which indicate that it may not be
built in its current form.
Peter Sterling
----- Original Message -----
From: Smith JR, Harry E <[email protected]>
To: Sat TCP mail list <[email protected]>
Sent: Tuesday, October 03, 2000 7:49 AM
Subject: Moving Targets
>
> I am not sure that LEO are a good answer. Have you thought about how many
> satellites you will need. I would guess around 5 or 6 in the orbit
trace.
> The second problem will be the handover of the data between the
satellites.
> ( I think this was one of the things that killed Teledisc)
>
> This means either cross links or a single hub that all satellites can see
> and the routing is on the ground. A third concern would be that
> utilization. Most of the time they would not be over Australia.
>
> A better idea would be a set of towers along the route like 3rd generation
> mobile system. While the standards only give 2Mbps for fixed station
unless
> you are talking about a bullet train, I think they could be considered as
> stationary. It will take a little thought.
>
> Depending on the services offered, you might be able to use part of a GEO
> transponder to feed the 3rd Gen Mobile from a single access point.
>
> Harry Smith
> Lockheed Martin Mission and Data Services
> 408 - 473 6491
>
> --------------------------------------------------------------------------
-- > - > Harry Smith > 408 473 6491 > > >
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