[Asterisk-Users] Satellite Providers

[Bill Ford]

The altitude of a geostationary satellite is about 37500 km for a
round trip distance of aboyt 75000 km. Light travels at 300,000
km/second, so you have a latency of about 250 ms per hop. That is just
for the transit time to and from the bird. Since you have a two way
conversation, a caller asking a question would have to wait a minimum
of  500 ms for a reply. This does not include any signal processing
that might take place. In other words, you will still have to account
for the "normal" voip latency. A satellite path might have several
hops, each adding its own 500 ms delay. With a geostationary
satellite, you really can't have anything approaching a full
duplex/real time telephone conversation. The conversations you have
would more closely resemble simplex two-way radio conversation.

That being said, if that's all you have, useful communications can be
had using this mode. The International space station, for instance.
uses several TDRS satellites to communicate with Houston. The big
thing is training the users.

Bill


On 5/11/05, Yiannis Costopoulos <lists at w2ns.com> wrote:
> Hi All,
> 
>         I am investigating the deployment of VoIP/* in Eastern European areas where
> there is no PSTN infrastructure. As you can understand DSL/Cable connections
> are a dream. The only option is satellite.
> 
> Does anyone know of any satellite providers that have low enough/acceptable
> delays for VoIP?
> 
> Thanks,
> Yiannis.
> 
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