Re: [gpsd-users] Help with extracting time information from GPS to NTPD

[The Crew]

On Thu, 10 Nov 2011 16:22:20 -0800
Jordan <address@hidden> wrote:

<snip>
> Thanks!  I downloaded the ntp source and recompiled from scratch with the
> SHM driver.  NTPD can now see the GPS time and is syncing to it.  Now I'm
> 
> noticing another issue where the reported time from the GPS is ~24 seconds
> ahead of the public time servers.  I did a quick google search and saw this
> matches up with Loran-C time vs UTC.  Is it possible the GPS is reporting in
> 
> Loran-C time?  If so, can I compensate for this in NTPD?
<snip> 

Sorry for the delayed response....apparently I'm 1209600 seconds behind UTC.

.This is from 

http://www.leapsecond.com/    
http://www.leapsecond.com/java/gpsclock.htm    (...don't know if it's accurate.)

<quote>
GPS, Global Positioning System time, is the atomic time scale implemented by 
the atomic clocks in the GPS ground control stations and the GPS satellites 
themselves. GPS time was zero at 0h 6-Jan-1980 and since it is not perturbed by 
leap seconds GPS is now ahead of UTC by 15 seconds.
Loran-C, Long Range Navigation time, is an atomic time scale implemented by the 
atomic clocks in Loran-C chain transmitter sites. Loran time was zero at 0h 
1-Jan-1958 and since it is not perturbed by leap seconds it is now ahead of UTC 
by 24 seconds. 
TAI, Temps Atomique International, is the international atomic time scale based 
on a continuous counting of the SI second. TAI is currently ahead of UTC by 34 
seconds. 
</quote>

...who knew?  ...not me. 

It doesn't answer your question...but you already (by this time)  have the 
answer for that..



-- 
The Crew <address@hidden>