[Asterisk-Users] Satellite Broadband and VOIP

[trixter http://www.0xdecafbad.com]

On Sat, 2005-08-27 at 12:14 -0700, Julius Igugu wrote:
> I use a satellite connection and VOIP is ok!  
> 
> It depends,mostly, on what you expect!  
> 
> There's an inherent delay in the system usually about 700ms - 800ms! but this
> is bearable.

That depends on how you define satellite and the network itself...
Satellites are things that orbit the earth (duh) but where they orbit is
critical to latency.  Some systems are in geostationary orbit and have
much higher latencies.  Radio signals go about the speed of light (just
to cut off anyone who wants to correct my 'about' comment ...  when
passing through matter even light slows down).  LEO (low earth orbiting)
satellites that are not fixed to a given location in the sky are much
closer, and have much ess latency.  The newer variant of artificial
satelites is a solar powered airplane, which is WAY closer and thus has
much less latency (about 18 miles so the latency is hardly detectable
from the RF link).  afaik there are no stratelites (what the solar
powered airplanes are now being called because they fly in the
stratosphere) in active deployment but there are companies planning on
doing those.  1 stratelite can do an area roughly the size of texas (for
non americans that is a very large area, google it if you want to know
the sq km/mi :)  At 18 miles you still need a good antenna system (wifi
has done 125 miles at 11mbps unamplified with a 300mw card so it is
possible ...)

A lot of satelite providers overload their networks for cost reasons
(its really expensive to upgrade the routing equipment) as such those
devices add extra latency to the mix, geostationary orbit is about 250ms
each direction so anything over 500ms is normally caused by routing
equipment not being able to transmit as quickly as it should ...

With the newer systems coming out it should be even better.  18 miles
would be no worse than wire based systems in most instances, provided
the equipment is upgraded regularly, and time to deploy, dost to
upgrade, etc are lower so that just might happen.


-- 
Trixter http://www.0xdecafbad.com     Bret McDanel
UK +44 870 340 4605   Germany +49 801 777 555 3402
US +1 360 207 0479 or +1 516 687 5200
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