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GPS Constellation, is the service in trouble?
 A report from the U.S. Government Accountability Office set a very stern and worrying tone this week.
In the summary it discusses the issues being experienced in supporting and maintaining the GPS constellation which is massively over budget and years behind schedule.
The report goes on to state that if the current difficulties are not resolved and replacements orbited on schedule there are;
" in 2010, as old satellites begin to fail, the overall GPS constellation will fall below the number of satellites required to provide the level of GPS service that the U.S. government commits to".
This isn't just a bean counters bleak summary either. Navstar is now three years behind in the launch schedule to replace satellites that are already long overdue for replacement.
Quite apart from the issues that exist in any billion dollar program, space brings its own unique difficulties and whereas there are stocks of some GPS satellites built and ready to go, the lack of launch vehicles and launch opportunities are not as easy to correct in the short term.
No-one is in any doubt as to the long term need for a GPS network and it is certain that the U.S. will do all they can to bring the network back up to full health, but, if there are any service issues you can be sure that civilian users will be the first to suffer, GPS is still primarily a U.S. Department of Defence service and so they will always get priority.
U.S. GAO Report in full.
| Comments
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 Posted by MaFt on Fri May 15, 2009 8:33 am |
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maybe it's time for galileo to start pulling their finger out as well as gps chip manufacturers to make sure all future receivers are compatible with both gps AND galileo (ya know, just in case!)
MaFt
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| Posted by Darren on Wed May 20, 2009 2:51 pm |
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Nice to see all the dailies printing this story today, slow as usual.
The bigger concern is that whilst no-one would want to allow it to fail, rocket launch is a difficult business and with it already being behind schedule we could be left with a network knobbled by failed hardware and no launched replacements.
Darren Griffin |
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| Posted by Darren on Thu May 21, 2009 9:07 am |
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I'm amazed at the cavalier responses to this issue being attributed to senior exec's at Tomtom and Garmin.
Tom Murray, vice president of market development for TomTom. "We are not concerned about this changing and there is no reason to believe it will. Quite the contrary, the U.S. government has pledged full support for GPS since 2000."
Ted Gartner, from Garmin, said in a statement. "There's no reason to fear that there will be a significant outage or service interruption."
A shockingly blase attitude. It was never suggested that the U.S. Govt did not fully support the Navstar Service but the issues are here and very real. There is a very real possibility of service interruption and the delays in launching replacement satellites will not disappear overnight.
If anyone spots someone with his head in the sand this weekend it could well be a Garmin or TomTom exec.
Darren Griffin |
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| Posted by MaFt on Thu May 21, 2009 10:50 am |
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yes, the US government have supported it since 2000. tomtom offer support to their customers too and we all know what THAT means...!! broken promises, delays, faults, bugs...!
MaFt
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| Posted by Pocketgps on Thu May 21, 2009 2:25 pm |
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I can't see the US Forces going without full coverage.
Think the main problem with the existing sats is the fuel needed for orbit station keeping is running low in some of them 
Having said that, there are lots of other sats that should have quite years ago and still continue to function.
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| Posted by G1LIW on Thu May 21, 2009 2:45 pm |
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It's would appear that it's not just the likes of the CEs of Garmin and TT et al that are burying their heads in the sand...
The bigger problem is not the personal satnav market, it's the commercial satnav market. Ever since the GPS system was opened up for civilian usage, all manner of uses have surfaced - including most importantly the use by commercial aircraft and shipping of GPS navigation systems.
This is an aspect that I suspect the USG hasn't fully thought through - the USG could well find itself lumbered with all manner of lawsuits for not maintaining an "essential safety product", for example!
Roger, G1LIW
Google Pixel 3a XL Android Smartphone | SatNav Sygic for Android | Waze for Android | CamerAlert for Android | Blog http://rogersblant.blogspot.com/ |
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| Posted by Arimus on Tue May 26, 2009 3:05 pm |
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GPS should never operate as the sole navigational data input source into any safety critical system, all GPS can be and should ever be is an aid not a definitive answer. Too many conditions both man-made and natural can cause the GPS signal to degrade for it to be classed as a safety system...
--<br>
Users a like a virus, each one causing a thousand tiny crises until the host finally dies.
51:35:00N 03:13:36W |
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| Posted by Arimus on Tue Jun 02, 2009 1:23 pm |
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(Ok; I'm replying to myself but this is some more info I've just worked on).
Taking the information from ftp://tycho.usno.navy.mil/pub/gps/gpsb2.txt and removing all the PRN's prior to 1997 (so 10 satellites) from the constellation and using Trimble's planning software for my location (Caerphilly) and today's date and almanacs:
1 hr 10 minutes with < 4 satellites, compared with just 20 minutes if the full constellation is operational.
Not brilliant but not too poor - and at no period would we lose total coverage, 3 sat's is enough for fairly accurate 2d fix.
--<br>
Users a like a virus, each one causing a thousand tiny crises until the host finally dies.
51:35:00N 03:13:36W |
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