[ntp:questions] Very large offset and jitter values after reboot

Nicola Berndt nb at komeda-berlin.de
Sun Aug 24 22:53:27 UTC 2008

Richard B. Gilbert schrieb:
> Nicola Berndt wrote:
>> Hello,
>> I have now successfully set up my machine to use a usb-gpd-mouse to set 
>> the time. Strangely every time I reboot I get results like this, wich 
>> settle down after a (not so short) while:
>>      remote           refid      st t when poll reach   delay   offset  
>> jitter
>> ==============================================================================
>>  GPS_NMEA(0)     .GPS.            0 l    9   64   37    0.000  -580.75 
>> 3965.19
>> The problem is, that this takes rather long and the computer's job 
>> actually is, to provide exact time outdoors right after booting..
>> I already tried what would happen if I did a 'hwclock --systohc' once 
>> things are settled, but with no luck. My driftfile btw. says -35.666 - 
>> looks good to me - and I am very worried about the huge jitter...
>> Any ideas for me, anyone?
>> Thx and regards,
>> ../nico berndt
> 1.  Don't reboot!  My Windows, Linux, Solaris, and OpenVMS systems will 
> all run until the power goes off for longer than the run time of my UPS.
> 2.  Start ntpd with the "-g" switch.  The -g switch tells it to get and 
> set the correct time.  Following startup, ntpd will discipline the clock 
> in the usual way.  It may take a relatively long time, around thirty 
> minutes, to settle into really tight synchronization.
> _______________________________________________
1, As I wrote already, the device has to work outdoors, where there is 
no unlimited power-source, so I have to reboot. Also I think, a computer 
that cannorttake a reboot has a problem wich needs to be adressed. Just 
my opinion, though..

2, I forgot to mention that I already do so, still takes too long to 
settle. I also don't understand what is taking so long, since - jitter 
or not - the nmea time is precise enough to just quickly set the time at 
startup and then let things go their way. Can someone explain that to me?

Best regards,
../nico berndt

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