[LEAPSECS] WP7A status

[Richard B. Langley]

Not just for navigation. The geodetic community time-tags GPS measurements with GPS
(System) Time and all RINEX observation files, for example, use GPS Time as the
measurement epoch time scale. But, there are also other high-level time scales
maintained by different GPS analysis centres as well as a merged IGS time scale. More
info here for those interested in the intracacies:
<www.ngs.noaa.gov/IGSWorkshop2008/docs/IGS2008-Senior.pdf>.
-- Richard Langley

Quoting "Matsakis, Demetrios" <matsakis.demetrios at usno.navy.mil>:


> The best way to get "Time" out of GPS is to apply the leap seconds and

> subframe 4 corrections of the broadcast GPS navigation message to GPS

> time, and get UTC(USNO) via GPS.  Most GPS receivers do this

> automatically. There can be calibration and latency issues, which are

> usually but not always below 10 ns.

> 

> GPS time itself is provided for navigation solutions.  That is why it

> does not incorporate leap seconds, and that is also why GPS time is

> steered by acceleration (not rate) to UTC(USNO), modulo 1 second, using

> the so-called bang-bang algorithm.

> 

> The best reference would be the ICD-GPS-202, which is written in style I

> would describe as "for engineers".

> 

> -----Original Message-----

> From: leapsecs-bounces at leapsecond.com

> [mailto:leapsecs-bounces at leapsecond.com] On Behalf Of Greg Hennessy

> Sent: Thursday, December 18, 2008 6:53 AM

> To: Leap Second Discussion List

> Subject: Re: [LEAPSECS] WP7A status

> 

> 

> > http://www.newscientist.com/article/mg20026875.400-calls-to-scrap-the-

> > leap-second-grow.html

> 

> The report has a sentence "GPS time is not a reference, it is simply an

> internal time for GPS system synchronization, as GLONASS time is and

> Galileo time will be."

> 

> Is what it takes to be a reference documented any where?

> 

> 

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===============================================================================
 Richard B. Langley                            E-mail: lang at unb.ca
 Geodetic Research Laboratory                  Web: http://www.unb.ca/GGE/
 Dept. of Geodesy and Geomatics Engineering    Phone:    +1 506 453-5142
 University of New Brunswick                   Fax:      +1 506 453-4943
 Fredericton, N.B., Canada  E3B 5A3
     Fredericton?  Where's that?  See: http://www.city.fredericton.nb.ca/
===============================================================================