[Asterisk-Users] Satellite Providers

[Terry H. Gilsenan]

  _____  

From: asterisk-users-bounces at lists.digium.com
[mailto:asterisk-users-bounces at lists.digium.com] On Behalf Of Michael D
Schelin
Sent: Thursday, 12 May 2005 7:32 AM
To: Asterisk Users Mailing List - Non-Commercial Discussion
Subject: Re: [Asterisk-Users] Satellite Providers
 
 The delay in the air is minor. Radio travels very fast through the air.
Almost at the speed of light. It's the electronics that are causing the
delays.  The less electronics touching your signal the better.   The up and
down is very fast.  But then you have all the converts and the land line
links to factor in.  Microwave also has delays such as the Motorola
equipment which is only half duplex.  This will also incress the time.  Max
is right, check into some ground based systems. 
 
 
<sigh>
 
geostationary orbit is about 38,000 km above the equator, a ping from a host
in the us to another host in the us via a vsat link will travel the
following distance:
 
(2 x Distance from HostA to Uplink) + (4 x 38,000km) + (2 x Distance from
Satellite NOC to HostB)
 
Which could be if HostA is directly connected to vsat...:
 
(2 x 10m) + (4 x 38,000km) + (2 x 1000km) =
20m + 152,000km + 2000km =
20m + 154,000km =
~154,000,000m
 
Which should take about 500ms plus about 50ms for _ALL_ the electronics in
between.
 
So ping times should be expected in the 550-800ms range for a good
connection.
 
I use satellite (vsat) all the time and I am using SIP and IAX2 with good
sound but about 800ms delay, which is ok once you get used to it.
 
Regards,
T
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