[LEAPSECS] WP7A status

[Matsakis, Demetrios]

Agreed, and I'm sure many other uses have been found for GPS time, as
well.  It wouldn't surprise if some poorly-programmed GPS receivers
ignore the UTC(USNO) correction and just put in leap seconds, for
example.

Both sides on this mailing list could use this example to promote their
case.  Opponents to a change would say that perfectly fine solutions
exist to handle leap seconds, while advocates would say that engineering
solutions naturally gravitate towards the timescales that don't jump,
whether or not they lead to confusion or suboptimal daily performance.

-----Original Message-----
From: Richard B. Langley [mailto:lang at unb.ca] 
Sent: Thursday, December 18, 2008 1:14 PM
To: Leap Second Discussion List; Matsakis, Demetrios
Subject: Re: [LEAPSECS] WP7A status

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-th

> > e-

> > 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/
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