Comments for The Nog

Comment on GPS Basics by Ted Driver

Ted Driver — Fri, 29 Apr 2011 16:00:43 +0000

lily,
A Least-squares formulation used used, such as can be found in books like:

Global Positioning System, Signals, Performance and Analysis

by Misra, Enge

Comment on GPS Basics by lily

lily — Sat, 26 Mar 2011 04:32:50 +0000

thank for your information above. i want to ask, what formula you use to calculate position error once we know GDOP?
tks

Comment on GPS constellation optimization analysis by MPacheco

MPacheco — Wed, 04 Aug 2010 04:15:35 +0000

Subject: SVN62 placement

Looking at FAA’s WAAS Satellite Status page, it looks like the new IIF SV1 satellite is right on top of PRN 30 (SVN 30).
http://www.nstb.tc.faa.gov/incoming/waas_sats.png

Considering:
1 – There’s already PRN12 close by
2 – The constellation optimization effort

Then why not position PRN 25 halfway between PRN 12 and PRN 16, so that it make the best possible contribution to the constellation ??? I’m assuming that PRN30 is the next satellite to be retired before IIF SV2 is launched, considering that we’re at the 32 PRN limit. Even if there are concerns about PRN12′s longevity, wouldn’t PRN30 be kept in residual status ?

I was under the impression that newer satellites would be positioned in a spread out configuration, providing for much better overall GPS geometry.

Perhaps this was just a launch issue, and IIF SV1 is about to the repositioned on a smarted position for optimum contribution to the GPS constellation.

Comment on GPS Error Budget by Parimal

Parimal — Mon, 19 Jul 2010 11:29:09 +0000

pl share information about GNSS I am designer of IRNSS payload form ISRO

parimal majithiya

Comment on SVN 49, PRN 1 URE too high by MPacheco

MPacheco — Thu, 17 Jun 2010 22:39:40 +0000

In that case, AFAIK, SVN49 isn’t going to be very useful at all for the GPS community. WAAS and EGNOS won’t use it (Raytheon/FAA/ESA already stated that). In the end it might be useful only for the standard, non precision user, and to a user faced with no fix without SVN49, using it as a last resort.

It seems to me that most IIR/IIRM (all except for SVN42/49) are still in perfect shape (I’m assuming since there’s no information to the contrary), when the 12 IIF are all in orbit, then all IIA’s will be decommissioned/put in residual status (there’s 11 IIFs to be launched and 11 IIAs left in operational status). Perhaps the first IIIA might be launched to take SVN49′s place and put SVN49 in residual status as well… It’s interesting that the latest IIF launch in slot B2 is just ahead of SVN49′s B6. Once IIF-1 is operational, couldn’t PRN30 (currently operational in slot B2) be moved from B2 to B6 ?

Comment on What’s the difference between SEM and YUMA almanacs? by Tony Babiarz

Tony Babiarz — Wed, 09 Jun 2010 15:44:35 +0000

Define SEM – the word. S________ E________ M_______?

Define YUMA – the word Y________ U________ M_______ A________?

Comment on What’s the difference between SEM and YUMA almanacs? by Propagator

Propagator — Wed, 12 May 2010 19:36:12 +0000

Very useful, thank you!

Comment on SVN 49, PRN 1 URE too high by Ted Driver

Ted Driver — Sun, 28 Mar 2010 13:43:19 +0000

Good idea! But, there is no chance that could happen – for at least three reasons. First and foremost, the Shuttle is not designed to travel to the heights the GPS satellite’s orbits reside in. The farthest the shuttle ever went was to service the Hubble Space Telescope, which still isn’t near the GPS satellites. Next, the last Shuttle mission will occur this year. With no more funding for the shuttle, it won’t be going anywhere. Third, even if it were possible to get there, the severity of the L5 problem on SVN 49 doesn’t warrant the cost of removing the L5 demo payload. Servicing a satellite in orbit is very tricky and damage can occur easily.

Comment on SVN 49, PRN 1 URE too high by MPacheco

MPacheco — Sat, 27 Mar 2010 23:35:58 +0000

Is there any chance at all, that with a successful launch of IIF-1, with a properly tested L5 payload, that a subsequent Space Shuttle mission could remove the L5 demo payload (space walk) restoring SVN49 into a standard, high quality GPS satellite ? No one have questioned that so far, so what the hell…

Comment on SEM and YUMA almanacs…they USED to give similar results…. by Vladislav35

Vladislav35 — Tue, 16 Mar 2010 20:35:23 +0000

Я писал что-то подобное, но у Вас тема более глубого раскрыта