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Old November 5th 11, 03:39 AM posted to sci.geo.satellite-nav,rec.aviation.ifr
macpacheco
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Default The CBO is proposing to kill GPS IIIB and IIIC

On Nov 4, 11:00*pm, HIPAR wrote:
On Nov 4, 7:33*pm, macpacheco wrote:

http://www.gpsworld.com/defense/news...et-office-issu...


...
The best option is the other way around, skip IIIA manufacturing, and
go straight to IIIB.
...


If the program really needs to be restructured I'd agree with that.
The crosslinks of IIIB add so much utility maintaining the
constellation. *That's a benefit for every user class.

But, the USAF touts this procurement as a 'Back to the Basics'
approach. *That philosophy resists changing requirements after the
design has been approved. *That's (partly) how GPS IIF got into severe
programmatic difficulties.

Then there are 'Color of Money' issues. *For those who haven't been
evolved with DoD funding, *funds are allocated along lines ranging
from basic R&D to procurement of approved materiel. *The first *few
IIIA satellites are funded with R&D funds and there's a legal
requirement to not cross these funding lines by spending in an
unauthorized manner.

Notwithstanding programmatic issues, restructuring would delay
delivery of the IIIB satellites allowing OCX to phase into the overall
modernization schedule. *I suppose it can be 'spun' that way.

--- *CHAS


Building 2 IIIA is an ok idea. It really reduces risk. But beyond
that, its unnecessary (as long as IIIB and IIIC gets built).

IIA birds are still there, serving us well enough, and just 3 more
launches and we'll have 24 operational birds even assuming all IIA
birds "already dead".

It's funny that schedules from 10 years ago assumed all IIF birds
launched by now plus quite a few IIIA, with L2C FOC and L5 IOC this
year, we're essentially 12 launches behind from those older schedules.

Even with the solar maximum degrading older birds, I'm still betting
double launches won't be needed for another 4-5 years, assuming one
single launch per year until then. That's even if they are needed. So
far there have been around one launch every 15 months, with no change
planned for the next year (considering lead time for launch
announcements - around 9 months).

Since we're talking about the GPS constellation status, IIF-2/PRN1 is
still performing quite worse than IIF-1/PRN25, with RMS URE around
70cm versus 30cm, hopefully this is a phase of building ephemeris/
clock prediction data, and performance will improve over the next
weeks (it has improved since activation). IIF-2 performance is worse
than IIR-M average.

Source: http://adn.agi.com/GNSSWeb/PAFPSFViewer.aspx (the last chart)