Mailinglist Archive: opensuse (1420 mails)

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Re: [opensuse] openSUSE + gpsd + PPS + NTP
Le 15/01/2014 14:39, Roger Oberholtzer a écrit :
On Wednesday, January 15, 2014 02:03:12 PM jdd wrote:
Le 15/01/2014 13:22, Roger Oberholtzer a écrit :
We already have the GPS in the systems. These are very high end inertial
navigation systems that have a GSP as a component. We use equipment from
http://www.oxts.com/. Another supplier is http://www.applanix.com/

yes, the question is do these device have a way to maintain clock when there
are no satellite?

They do. But I don't know how consistent they are. We would not collect data
when the GPS is in that state anyway. I think we will gate having the GPS
obtain a sat fix. When that happens, the system ntp init script can then do
it's thing.



ntp is certainly not as good as a professional time keeper like the one you have in your high end GPS. Did you ask the GPS maker about this?

lot of things makes gps (satellite) clock out of sync, let only the distance and resulting travel time that needs correction.

a correct (usual grade) quartz clok is probably enough for any work under the 1s a month drift. I use a Wave casio clock, under €100 and radio piloted and always in sync.

PC original clock was horrible, I never understood really why a better clock was not implemented, even at this time quartz clocks where pretty cheap...

in conclusion, You should probably ask ntp to use the gps clock satellite or not. By the way is there a way to compare the gps internal clock and the satellite time?

jdd

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