Satellite IP

Lamar Owen lowen at pari.edu
Mon Jan 10 13:37:53 CST 2011


On Monday, January 10, 2011 01:28:07 pm Jay Ashworth wrote:
> My motivation for asking the question *here* was of course to get the operator
> perspective on the actual transport, if anyone had any.  

I helped a radio station put together a remote trailer using a mobile satellite system back in 2004; SDN was the provider.  Bandwidth we had available was I believe 1.5MB down and 384K up, burstable to 512K IIRC.  Mobile satellite operations is a trip, especially with the 4 watt uplink transmitter required at the time for the wide uplink bandwidth.  

For the target use, UDP video and audio streaming, it worked very well once the system linked up; satellite acquisition and clearance for uplink transmitter RF turnon was typically a half an hour or so.  When using TCP, however, the latency was noticeable.  Once the stream started and slow-start finished the bandwidth was what you'd expect from a terrestrial circuit, but slow-start was really slow, thanks to the propagation time to and from geosync orbit.

These systems had great use for VoIP PBX trunks for setting up a field phone system; the IP phone 'extensions' connected with WiFi, and the PBX itself was in the trailer, with the PBX to outside trunks handled by the satellite link.

The system was decommissioned just this past year due to the uplink bandwidth cost, the intermittent system use, and the penetration of G3 data services in the area.




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