Re: [time-nuts] Speaking of Costas loops (WAAS)
Hi
Yes, this has basically become a debate about weather WAAS sat's do or don't
contribute to a directly to a nav solution rather than just provide
correction information.
Bob
-----Original Message-----
From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On
Behalf Of David J Taylor
Sent: Thursday, July 11, 2013 12:57 PM
To: 'Discussion of precise time and frequency measurement'
Subject: Re: [time-nuts] Speaking of Costas loops (WAAS)
Hi
From the US patent:
"... and possibility of extending the operating range by allowing increased
separation of reference and base receivers by incorporating ionospheric
models provided by WAAS"
To me that says - position data from WAAS, carrier from GPS.
I had understood that WAAS provided data such as what were dead or
problematic satellites, and ionospheric data which allows the positions
derived from standard GPS satellites to be more accurately determined
through extra corrections, but WAAS satellite transmissions did not of
themselves contribute to to a position determination. Was I wrong in this,
or perhaps outdated?
Cheers,
David
SatSignal Software - Quality software written to your requirements
Web: http://www.satsignal.eu
Email: david-taylor@blueyonder.co.uk
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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@blueyonder.co.uk
Hi
It could be 10 pounds of stuff and 340 pounds of shielding …
It also could be 10 pounds of WAAS and 340 pounds of something they don't want to talk about.
Bob
On Jul 11, 2013, at 3:17 PM, David J Taylor david-taylor@blueyonder.co.uk wrote:
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@blueyonder.co.uk
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To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.