Hi The gotcha is that if the duration gets long enough, the numbers on a GPSDO will get silly small. You very much have to decide what time duration is appropriate to your system / application. If you always run your frequency counter on a 1 or 10 second gate …. you really don’t care about 10,000 seconds.
Bob > On Jul 2, 2019, at 7:15 PM, Chris Burford <cburfo...@austin.rr.com> wrote: > > Hi Bob, > > I'm seeing 4.22E-12 as the slope value in the upper right of the TimeLab > phase difference plot. Is that telling me that my DUT is within +4.22ps / sec > from my reference 1PPS for the 24 hour measurement duration? > > I have attached a screen capture that will hopefully make its way through for > viewing. > > Thanks, > > Chris > > On 07/02/19 11:50:10, Bob kb8tq wrote: >> Hi >> >> The difference in seconds between the start phase and the end phase divided >> by the number >> of seconds duration gives you the parts in whatever of the error. >> >> If you see 1us ( = 1x10^-6 seconds) of change in a second, you are off by 1 >> ppm (or 1x10^-6). >> If you see 1 us of change in 1,000 seconds you are off by 1 ppb (or >> 1x10^-9). At a bit over 10 >> days (1,000,000 seconds) your 1 us change is 1 ppt (or 1x10^-12). >> >> Bob >> >>> On Jul 2, 2019, at 10:17 AM, Chris Burford<cburfo...@austin.rr.com> wrote: >>> >>> Is the slope value for the phase difference shown in TimeLab an average of >>> the overall data sample duration? The reason I ask is that my service >>> manual for my RFS says: >>> >>> /"//A faster way to make the comparison between the reference frequency and >>> the DUT is to use the time interval measurement mode of the counters. In >>> this case, the time intervals between the 10MHz zero crossings of the >>> reference frequency and the DUT are measured and averaged. If this time >>> interval changes by less than 10ps per second, then the DUT is within 1 >>> part in //10^11 of the frequency reference."/ >>> >>> I'm just curious if the phase difference slope value can be plugged in to >>> this equation. >>> >>> Regards, >>> >>> Chris >>> >>> >>> _______________________________________________ >>> time-nuts mailing list --time-nuts@lists.febo.com >>> To unsubscribe, go >>> tohttp://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> _______________________________________________ >> time-nuts mailing list --time-nuts@lists.febo.com >> To unsubscribe, go >> tohttp://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > <Phase Diff Slope.png> _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
