Satellite latency (fwd)

Wed Feb 27 14:08:08 UTC 2002

>The radius of the earth is about 6400km.  Geostationary orbit is, as
>you note, 36000km above the equator.  The path from the satellite to
>the North Pole is the hypotenuse of a right triangle with legs of
>6400km and (6400+36000)km.  That gives a distance from the North Pole
>to the satellite of 43000km.  It's reasonable to conclude that the
>distance from either New York or San Diego is less than that.

Is that 36000 km above the equator measures from the surface of the earth, 
or the center of the earth?  I would assume that most companies would use 
the surface of the earth to determine the orbit, or sea level.

Looking at a spam I just received from satcast.com, it looks like they are 
considering the distance from the dish to the satellite to be roughly 44000 
miles.  That's roughly  70000 km.  Assuming that they are stating that from 
the dish to the bird, that would account for the larger RTT times that 
people see.

My real problem with these directpc type systems are two fold.  The first is 
that these systems use a USB connection.  I use wireless at home since I 
have a number of laptops.  I certainly am not willing to tie myself down to 
a usb cable.

The second problem is that the users are addressed using rfc1918 address 
space and are translated via nat to the Internet.  This may mess up any 
number of applications that I use, including VPN software.  Add to this the 
first problem, and suddenly I have two levels of NAT that I have to contend 
with, one on my windows machine connected to the USB cable (with Internet 
sharing), and one at earthlink's edge.

Those are what's keeping me at dialup, even though I only get 28.8 at best.  
Well... that and the fact that I can't get cable where I live, and the CO is 
sonething like 15 miles away (not that they can spell DSL out here).

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