[time-nuts] Speaking of Costas loops (WAAS)

David J Taylor david-taylor at blueyonder.co.uk
Thu Jul 11 15:17:22 EDT 2013


If you look at the pictures here

    http://www.orbital.com/NewsInfo/Publications/Galaxy_Fact.pdf

the satellite on the right has things sticking out the bottom, in the
back corner, that are missing on the others and that look a lot like
the antennas on GPS satellites.  The WAAS satellite is also 350 pounds
heavier than the other two even though the C-band payload is identical
on all three, so it seems like there could be a fair amount of extra
stuff added for WAAS support.

Dennis Ferguson
_______________________________________________

Thanks, Dennis.  The antennas don't surprise me, as they would need to 
produce a near-whole-disk coverage at a similar ground received power level 
to the GPS satellites.  That extra weight /does/ sound a lot if it were 
"just" a simple transponder for earth produced information.  Here in Europe 
was have three EGNOS sources (all on other satellites, I believe), and I 
don't believe they play any part in actual position fixing, but they do 
provide extra information enabling the fix to be refined.

Cheers,
David
-- 
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor at blueyonder.co.uk 



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