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lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:2
reply to TomS_

Re: Do Satelites have routers in them?

Yes, broadband satellites use polarity and frequency to provide enough isolation between TX and RX.

Someone asked about 140gbps spec for viasat-1 ... imagine there was a single large antenna receiving each beam at highest modulation ... then their hub transmitter would be pushing out that much raw data. This is higher than other broadband satellites because of more beams and some frequency tricks explained here:
»www.viasat.com/broadband-network ··· ess-pcma


54067323

join:2012-09-25
Tuscaloosa, AL

1 edit
said by lutful:

This is higher than other broadband satellites because of more beams and some frequency tricks explained here:

There are not more beams with PCMA as those are dependant upon the design of the bird, it PCMA is however for all intents and purposes predicative TDMA, that may and that is a big may, provide additional bandwidth per channel efficiency at the cost of higher transponder power demands and since on-board power is limited and metered out on a per channel/transponder basis users of PCMA may or may not realize the claimed benefit of higher bandwidth by deploying PCMA.

lutful
... of ideas
Premium
join:2005-06-16
Ottawa, ON
kudos:2
said by 54067323:

said by lutful:

This is higher than other broadband satellites because of more beams and some frequency tricks explained here:

There are not more beams with PCMA ...

I wrote frequency "tricks" because I share your concerns about PCMA. Otherwise, I just implied that Viasat-1 has more beams than typical broadband satellites.


54067323

join:2012-09-25
Tuscaloosa, AL

3 edits
said by lutful:

I just implied that Viasat-1 has more beams than typical broadband satellites.

Beams or more precisely beam shaping is an old technology that allow the designers to aim power where it is desired versus just blanketing a continent and are nothing more than precise modifications of the downlink antenna reflector.

As for Viasat1 if you look into the company it becomes clear they are the remnants of WildBlue cobbled together hoping this one will make them profitable, but I wouldn’t hold my breath waiting for that to happen.

And as for PCMA it is really nothing more than carrier within carrier versus the standard single carrier per channel and is a technology that was developed back in 2010 so it's really not breaking news either.