In general, we do not recommend the use of our system
over a Satellite (SAT) Internet connection. However,
some customers do. There are a few technical issues
related to SAT links that can cause problems:
- Round Trip Time (RTT) Delay. Most SAT's used for
Internet connections are geosynchronous. This means
that their orbit period is the same as the length
of a day, so they are stationary in relationship to
a given point on the ground. To achieve such an orbit,
the SAT must be 22,235 miles (35,784 km) above the
earth's surface. Radio waves travel at the speed of
light, but even the speed of light takes a noticeable
amount of time to travel that distance 4 times (up
and back twice for a complete round trip from your
UA to our servers.) This delay, when added to other
factors on the ground, can cause delays anywhere from
500 ms to 1000 ms (1/2 second to 1 second.) It can
be very difficult to carry on a conversation when
there is that much delay.
- Network Jitter. Probably more important than RTT
Delay itself is the consistency (or lack of) of the
RTT Delay. Some packets take longer than others to
reach their destination which can cause voice data
to arrive out of order and possibly be dropped. We
have found that many SAT Internet connections have
this failing. Many UA's have adaptive Jitter Buffers
which can absorb some small inconsistencies in RTT
delay, but given large inconsistencies, the result
is often an almost unusable connection.
- Lack of uplink bandwidth. Typically SAT Internet
connections are asymmetrical with their download bandwidth
being much higher than their upload bandwidth. If
your uplink bandwidth is lower than the bandwidth
required by the vocal codec you are using (see the
Knowledge Base article on Codecs), then you will not
be able to use the connection for voice calls reliably.