HI Very neat !!!
Bob > On May 18, 2016, at 2:57 AM, [email protected] wrote: > > This is my first contribution to the Time-Nut list, but I am a follower for > several years. > I have made 30 days phase difference measurements of an HP5065a versus a > modified Thunderbolt GPSDO (got a MV180 oscillator) with a Fluke PM6681, > and recorded the results with Timelap. Starting signal of the PM6681 was the > 5MHz of the HP5065A, stop signal the 10MHz from the Thunderbolt. A single > measurement was triggered once a second from the PPS of the TB. > I also have a weather station at 6 km distance away, which records barometric > pressure at time intervals of 10 minutes. Out from these measurements, I > divided > my phase measurements into 10 minute intervals, calculated the 10 min average > frequencies and made a linear regression with the 10 minute pressure > measurements. > I got a slope of 3.86E-14/hPa frequency difference versus pressure. > Then I corrected the original 10 min average frequency measurements with the > result from the linear regression and imported the original and the corrected > datasets into Timelap. > The influence of the barometric pressure to the ADEV for long time intervals > is shown in the picture. > Just for fun, to render the pressure sensitivity visible for the human eye, I > removed the noise of the GPSDO by generating a plot of overlapping 1 day > frequency averages in 10 minute time intervals. On the second picture you can > compare it with the 10minute pressure data from the weather station. I think, > it is quite impressive. The calculated slope out of these overlapping > averages was with 3.74e-14/hPa a little bit different compared with the non > overlapping dataset. > > Best regards > Wulf<HP5065A ADEV.png><HP5065A freq and > pressure.png>_______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
