MnGCA

spinowner · Posted: Mon May 18, 2009 7:27 am Post subject: GPS accuracy may worsen

I saw this link at the Iowa Geocachers Organization forum.

http://db.tidbits.com/article/10276
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Pear Head · Posted: Mon May 18, 2009 10:03 am Post subject: Re: GPS accuracy may worsen

Arcticabn · Posted: Mon May 18, 2009 10:47 am Post subject:

Mostly filled with half truths.

All of the Block 1 Sats went off line in 18 Nov 1995.

There are a series of Block II sats.

Block II totaled 9 and went out of service in 2005

Block IIA total 19 sats 6 of which were taken out of service in Jan 2009

Block IIR total 12 sats all of which are in service

Block IIM total 8 sats all of which are not launched (will replace aging Block IIA sats

Block IIF total 12 sats currently under contstruction

Block III - currently in design. GPS III, will give new navigation warfare (NAVWAR) capabilities to shut off GPS service to a limited geographical location while providing GPS to US and allied forces. GPS III will offer significant improvements in navigation capabilities by improving interoperability and jam resistance.

As of 2002 the constellation of 27 operational GPS satellites consisted of three different generations, or block types. Specifically, the constellation included 3 Block II, 18 Block IIA, and 6 Block IIR vehicles. Of the 21 older II/IIA satellites, 20 were past their contracted mean mission duration of 6 years, and 17 are past their design life of 7.5 years. Moreover, of all the satellites, 13 were one component away from mission failure, and nine are one component away from bus failure. Since that time 17 additional satellites have been launched to replace aging platforms.

The is a continual build and launch schedule of current Block II design which will if necessary be extended to additional platforms if the Block III falls behind schedule either due to the contractor or the government.
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