[ntp:questions] SIRF time output wobble, GPS or NTP fault?

David Lord snews at lordynet.org
Thu Mar 8 14:51:14 UTC 2012


Ron Frazier (NTP) wrote:

....

> Based on the aforementioned web page, it looks like the possible 
> validity fields are as follows:
> 
> GPRMC sentence - POS_STAT
> GPGLL sentence - POS_STAT
> GPGGA sentence - FIX_MODE
> GPZDA sentence - none, as you observed
> GPZDG sentence - V or maybe signal strength
> 
> I don't know if my GPS will do GPZDG.  Otherwise I might try it.  It may 
> be proprietary to some GPS's.
> 
> We still don't know if NTPD recognizes any of these fields, or if the 
> behavior is different in Windows and Linux.  If it does, I might switch 
> back to another sentence.  However, I already know it will increase my 
> NMEA jitter.  If I can get PPS working, that won't matter as much.  
> That's not an option with the BU-353 though.
> 
>> []
>>> This is the part of my ntp.conf file in windows related to stats.  Do 
>>> I need to add anything else?  I think all the stats are already on in 
>>> Linux.
>>>
>>> enable stats
>>> statsdir "C:\NTP Service\NTP\etc\"
>>> statistics loopstats
>>>
>>> Thanks for the help.
>>>
>>> Sincerely,
>>>
>>> Ron
>>
>> You may want to add peerstats:
>>
>> statistics loopstats peerstats
>>
>> so that you can look at the 5th column of the results, and read the 
>> offset for each clock.
>>
>> Cheers,
>> David
>>
> 
> Peerstats is now on.  Not totally sure what to do with it, but it's there.
> 

There are scripts in the distribution to produce summary files
from the stats files:


eg. peer_summary:

peerstats.20120126
        ident     cnt     mean     rms      max     delay     dist     disp
==========================================================================
192.168.59.67    315    0.738    0.537    1.194    0.593    6.525    3.033
127.127.20.2    1350  -64.665   14.597   60.075    0.000    2.369    1.781
127.127.22.2    1350   -0.000    0.004    0.036    0.000    0.928    0.928
192.168.59.22    287    0.595    0.345    1.033    0.588    5.302    2.462
81.187.61.69     161    1.499    0.729    1.541    0.770   11.659    5.202
192.168.59.242   273    0.786    0.753    1.887    1.188    7.113    2.734
81.187.61.74     147    1.196    0.605    1.437    1.025   12.334    5.765
192.168.59.210   269    0.923    0.866    2.079    1.190    6.375    2.953


eg. loop_summary:

loopstats.20110922
loop 1350, 6+/-41.5, rms 5.9, freq -35.51+/-0.639, var 0.227

loopstats.20110923
loop 1350, 6+/-27.4, rms 3.2, freq -35.79+/-0.157, var 0.090

loopstats.20110924
loop 1350, 8+/-24.8, rms 3.7, freq -35.76+/-0.171, var 0.067

loopstats.20110925
loop 1350, 9+/-28.2, rms 5.6, freq -35.31+/-0.555, var 0.191


David




More information about the questions mailing list