[ntp:questions] Stick to PPS, even if the prefer server fails

David Mills mills at udel.edu
Tue Mar 24 21:29:33 UTC 2009


alkopedia,

Your PPS signal is working, but not necesarily discipining the kernel. I 
can't help you with Linux.

Dave

alkopedia at googlemail.com wrote:

>On Mar 23, 5:00 am, Dave Hart <daveh... at gmail.com> wrote:
>  
>
>>Dr. Mills,
>>
>>Thank you for your confirmation.  The original poster should be
>>satisfied, assuming their kernel time is being disciplined directly by
>>their cesium standard.
>>    
>>
>
>What do I have to do to use the kernel discipline?
>At the moment I'm using a Linux kernel 2.6.28.1 with LinuxPPS patch
>(http://wiki.enneenne.com/index.php/LinuxPPS_support). The PPS signal
>is connected via RS232 DCD pin and used by the ntpd refclock_atom
>driver.
>I don't see the PPSTIME bit in ntptime:
>
>monitor202[~]# ntpq -pn
>     remote           refid      st t when poll reach   delay
>offset  jitter
>==============================================================================
>+192.168.12.3    .GPSi.           1 u    8   64  377    1.047
>2.127   0.194
> 192.168.12.5    .INIT.          16 u    -  128    0    0.000
>0.000   0.000
>o127.127.22.0    .PPS.            1 l    8   16  377    0.000
>-0.027   0.028
> 192.168.12.11   192.168.12.3    13 u   10   64  377    0.979
>-152.47   0.147
>
>monitor202[~]# ntpq -crv
>assID=0 status=21b4 leap_none, sync_atomic/PPS, 11 events, event_peer/
>strat_chg,
>version="ntpd 4.2.4p5 at 1.1541-o Mon Dec  1 14:26:35 UTC 2008 (1)",
>processor="i486", system="Linux/2.6.28.1elan", leap=00, stratum=2,
>precision=-16, rootdelay=0.000, rootdispersion=0.351, peer=63523,
>refid=PPS(0), reftime=cd739da1.0860c62e  Tue, Mar 24 2009
>17:57:53.032,
>poll=4, clock=cd739da3.1eedef80  Tue, Mar 24 2009 17:57:55.120,
>state=4,
>offset=-0.032, frequency=77.428, jitter=0.026, noise=0.092,
>stability=0.005, tai=0
>
>monitor202[~]# ntptime
>ntp_gettime() returns code 0 (OK)
>  time cd739daa.7ecb5320  Tue, Mar 24 2009 17:58:02.495, (.495290872),
>  maximum error 5074 us, estimated error 91 us, TAI offset 0
>ntp_adjtime() returns code 0 (OK)
>  modes 0x0 (),
>  offset -30.903 us, frequency 77.428 ppm, interval 1 s,
>  maximum error 5074 us, estimated error 91 us,
>  status 0x2001 (PLL,NANO),
>  time constant 4, precision 0.001 us, tolerance 500 ppm,
>
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>  
>




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