[time-nuts] Datum FTS 4065B Plot
brooke at pacific.net
Wed May 14 15:26:47 EDT 2008
If you look at the plot I attached as a .pdf you can see that the current slope
looks like a nice straight line covering almost 4 days so temperature is not a
factor. The only factor I can think of is magnetic field. I guess the next
step is to rotate the box 90 degrees and see what happens unless there's some
I haven't got the automatic logging started yet, but it's in process.
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Tom Van Baak wrote:
>> I've been looking at the 4065B Cesium standard vs. GPS this month. After the
>> plot showed a slope of 472E-15 the frequency offset was changed from zero to
>> 472 on 8 May (gambling on the sign). For the next couple of days the points
>> all were in a box 20 ns high. BUT then the slope changed. It's now got a
>> positive slope that's very close to 472E-15 and the frequency offset is at 472
>> not zero. See attached plot.
>> What might be causing this? For example the 4065B is just sitting on a chest
>> of drawers and might be moved or rotated a little from time to time. Is there
>> a requirement that it be in a temperature controlled room on a concrete pillar
>> to get into the E-14 area?
>> It just turns on better than 5E-13 and the attached plot seems to indicate that
>> it and be manually adjusted to parts in E-14 but so far I've not been able to
>> do that.
> At the level of e-14 and e-15 you might need weeks of data to
> separate the normal flicker noise from any clear frequency
> offset or drift trends. Yes, it's quite possible that environmental
> effects are also polluting your data. You can either control
> temperature, or just collect temperature data and see if there
> is a correlation with your standard.
> Do you have a continuous set raw GPS-Cs 1PPS data that I
> can look at to see if I can help you?
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