On Mon, May 07, 2012 at 05:06:55PM +0100, Ed W wrote: > So my theory is that gpsd is measuring the timestamp of the end of > the ZDA sentence (and working that back to get the initial > timestamp) and this gives an additional 0.5-1ms jitter that might > not be there if we measured the timestamp of the initial $. If so > then I might expect to see a jitter distribution which is positively > skewed (every time the last character drops into a later 1ms read) > > Can someone give some guidance on the correct statistics to plot to > investigate this further? I'm a little unsure on how to interpret > the stats in /var/log/statistics.log also /var/log/tracking.log > seems interesting?
I think the best data for this investigation are the actual offsets measured by the refclock driver, i.e. cooked offset in the refclocks log. The dispersion of the filtered sample (- in raw offset) could be perhaps interpreted as a jitter divided by some small constant. The tracking log is more about the local clock and the statistics log is from already filtered data from refclocks. -- Miroslav Lichvar -- To unsubscribe email chrony-users-requ...@chrony.tuxfamily.org with "unsubscribe" in the subject. For help email chrony-users-requ...@chrony.tuxfamily.org with "help" in the subject. Trouble? Email listmas...@chrony.tuxfamily.org.
