[ntp:questions] Performance of the shared-memory reference clock

Loretta Goldberg loretta_1958 at yahoo.com
Tue Feb 23 16:28:48 UTC 2010

The shared-memory reference clock was modified (ntp-4.2.5p138) to collect data each second, rather than once per polling interval.  What would be the impact of this modification on how accurately I can estimate the current time from a given GPS?  
If my system requirements specify that I have to use a version of NTP that predates this modification, can I attain the same accuracy from my GPS?
Is the limitation that it will take me longer to synchronize to my GPS?  Or does the increased polling interval prevent me from attaining the same degree of accuracy in my estimation of the current time?
I do have both a pulse-per-second signal and a time-of-day message coming from my gps.  The pulse-per-second will be designated as the "prefer" instance of the shared-memory reference clock.  The time stamp for the pulse-per-second will not be passed to NTP until NTP has "locked on" to the time stamp coming from the time-of-day message.


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