[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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