Mailinglist Archive: opensuse (1420 mails)

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Re: [opensuse] openSUSE + gpsd + PPS + NTP
If you have a bios clock you are probably good. Any pc grade clock will be
within a couple minutes even after months in the powered off state.

Should be Easy to test this, just put two of them away somewhere and check the
drift after a month with no gps and no Internet connection.

Your local clock should be fine.


Roger Oberholtzer <roger@xxxxxx> wrote:
On Wednesday, January 15, 2014 08:08:29 AM Per Jessen wrote:
Roger Oberholtzer wrote:
On Tuesday, January 14, 2014 11:47:31 AM John Andersen wrote:
NTP will often NOT compensate for several hours of difference.

This is a worry. These systems are in vehicles on the road. We have
no
control over the time on the PC clock at boot.

The ntp init script used to run 'ntpdate -g', I'm sure it does
something
similar now. That'll set the clock, but with a jump, not a slow
adjustment.

Provided that the GPS is providing times at the time the init script
runs.
What if the user turns on the measurement system in a parking garage
where
there is no satellite available? Time will not be available when the
init
script runs. In typical Catch 22 fashion, the operator cannot know the
GPS has
acquired sats and thus be able to provide correct time unless they turn
on the
computer. At which time the init script runs. We do not want the
operator to
have to assess if the GPS is ready and then run the init script. Maybe
we will
need to modify the script so it runs a program that waits until the GPS
has
satellites before proceeding? I suspect that this is the bigger issue
than if
the BIOS clock is within one hour of UTC.

--
Yours sincerely,

Roger Oberholtzer

Ramböll RST / Systems

Office: Int +46 10-615 60 20
Mobile: Int +46 70-815 1696
roger.oberholtzer@xxxxxxxxxx
________________________________________

Ramböll Sverige AB
Krukmakargatan 21
P.O. Box 17009
SE-104 62 Stockholm, Sweden
www.rambollrst.se
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