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

Ron Frazier (NTP) timekeepingntplist at c3energy.com
Fri Mar 9 00:13:12 UTC 2012


On 3/8/2012 9:51 AM, David Lord wrote:
> 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
>

That's pretty cool.  I'll have to check them out.  Does that work under 
Windows and Linux, and, where would I find them?

Sincerely,

Ron

-- 

(PS - If you email me and don't get a quick response, don't be concerned.
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Ron Frazier
timekeepingdude AT c3energy.com



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