[ntp:questions] Odd results with Oncore UT+ ref clock

Richard B. Gilbert rgilbert88 at comcast.net
Tue Feb 1 18:11:17 UTC 2011


On 2/1/2011 12:44 AM, Chris Albertson wrote:
> I just set up a new Linux based stratum 1 server using a Motorola
> Oncore UT ref. clock.  Seems to mostly be working except for a
> periodic anomaly Look at this output from ntpq:
>
> chris at atom:~$ ntpq -p
>       remote           refid      st t when poll reach   delay   offset  jitter
> ==============================================================================
> oGPS_ONCORE(0)   .GPS.            0 l    6   16  177    0.000    1.401 377.675
> +dp.cx           128.227.205.3    2 u   39   64  377   86.133   -4.062   0.423
> +64.73.32.134    129.6.15.28      2 u   50   64  377   75.212    1.608   0.804

Did you, by any chance, start NTPD a few seconds before issuing the 
above command?
>
> The I do nothing but wait and try again and get this
>
> ==============================================================================
> *GPS_ONCORE(0)   .GPS.            0 l   64   16  360    0.000    0.816   0.115
> +dp.cx           128.227.205.3    2 u   16   64  377   85.835   -3.523   0.642
> -64.73.32.134    129.6.15.28      2 u   24   64  377   73.538    1.635   0.869
>
>
> Some times the offset and jitter will be as low as 0.004 and 0.002
>
> In the clockstats file it looks OK I see many lines that, I think say
> the GPS sees 5 to 8 satellites with good signal
>
> 55593 20317.217 127.127.30.0 3505527516.999033699 2011 32  5 38 37 36
> rstat   08 dop  0.0 nsat 12,7 traim 1,0,0 sigma 44 neg-sawtooth -30
> sat 88088878
> 55593 20318.217 127.127.30.0 3505527517.999037365 2011 32  5 38 38 37
> rstat   08 dop  0.0 nsat 12,7 traim 1,0,0 sigma 44 neg-sawtooth -41
> sat 88088878
>
>
> What I've hoping is that before I spend many hours on this someone
> else has seen it and knows
>
> =====
> Chris Albertson
> Redondo Beach, California

  It looks as if  you issued that ntpq -p command a minute or so after 
starting NTPD.

NTPD can take up to thirty minutes to get a halfway decent approximation 
to the correct time and up to ten hours to achieve the best possible 
results.  It was meant to be run twenty-four hours a day and seven days 
a week.

If you want to run "nine to five" it's a poor choice.  If that's what 
you want, consider a program called "chrony" which can give you a decent 
approximation in a few minutes.




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