[time-nuts] HP5065A environmental sensitivities

[Bob Camp]

HI

Very neat !!!

Bob

> On May 18, 2016, at 2:57 AM, DG2OM at gmx.de 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>_______________________________________________
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