[ntp:questions] Acutime Gold

David Lord snews at lordynet.org
Fri Aug 16 12:55:18 UTC 2013


David Lord wrote:
> Mark C. Stephens wrote:
>> This is what I had with no time1:
>>      remote           refid      st t when poll reach   delay   
>> offset  jitter
>> ============================================================================== 
>>
>> oPPS(0)          .PPS.            0 l   13   16  377    0.000   
>> -0.007   0.005
>> *GPS_PALISADE(0) .GPS.            0 l   12   16  377    0.000    
>> 0.008   0.003
>>
>>
>> And this is what I get with time1 of 0.015
>>      remote           refid      st t when poll reach   delay   
>> offset  jitter
>> ============================================================================== 
>>
>> oPPS(0)          .PPS.            0 l   10   16  377    0.000    
>> 0.012   0.005
>> *GPS_PALISADE(0) .GPS.            0 l   10   16  377    0.000   
>> 15.031   0.008
>>
>> Seems I have put myself out 15 ms by adding time1 0.015
>>
>> Also in my ntp.conf I have:
>> saveconfigdir /etc/ntpd
>> however if I do a ntpq -c saveconfig it comes back asking for a filename.
>> Have I not compiled saveconfig mechanism in or something?
>>

.....

> 
> You don't need to get a very accurate time from the GPS as the
> PPS when present sets the offset. Some GPS are a disaster when
> used to set a clock and several of my devices have variations
> of > +/- 50 ms. Your GPS_PALISADE is very accurate by comparison.
> eg.
>     fudge 127.127.28.0 stratum 4 time1 0.024 refid MSFa
>     fudge 127.127.20.2 stratum 6 time2 0.417 refid GPSb
> 
> Note that I don't really want either to be used for offset as
> neither is as good as internet time.
> 
> If you really want to fudge out the time offset of GPS_PALISADE
> you would need 0.000008 (s) or better run peer_summary for a
> while so you can get an average in case that value varies.
> 

Hi

from my peer_summary

ident                mean(ms)  rms     max(ms)
127.127.22.2 (.PPSb.)   0.000   0.004    0.004
127.127.20.2 (.GPSb.)  -0.125  20.180   69.578

Peer and loop summary are scripts from the ntp distributions.
4.2.6p5 has both a perl and .sh versions.

David



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