Hi A lot depends on just what is being measured.
If you are looking at three PPS signals, you *might* be running on the internal reference for a second. If you are comparing 10 MHz signals, the max time is 100 ns. Getting (say) 1 ps accuracy in the first means 1x10^-12 / 1 = 1 ppt on your local reference. In the second case it’s 1x10^12 / 100 x 10^-9 = 100,000 ( so 10 ppm). In the first case the local reference could matter a lot. In the second case … not so much. The most common approach is to run the local references all off of a “good” standard and to align the signals so that it’s not a major issue in the results. ( so keep your 1 PPS signals close to each other). Bob > On Apr 3, 2022, at 5:50 PM, Marek Doršic <marek.dor...@gmail.com> wrote: > > Hi, > > 3-cornered hat was mentioned several times past days. What reference > should be used for time interval counters comparing oscillator pairs? > Should internal references be used what ever bad they are? A home standard > (4th oscillator)? The third oscillator C when comparing pair A-B? ...? > > Thanks, > .marek > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an > email to time-nuts-le...@lists.febo.com > To unsubscribe, go to and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
