[time-nuts] Datum FTS 4065B Plot

Brooke Clarke brooke at pacific.net
Wed May 14 15:26:47 EDT 2008

Hi Tom:

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 
other suggestions.

I haven't got the automatic logging started yet, but it's in process.

Have Fun,

Brooke Clarke
http://www.prc68.com/P/Prod.html  Products I make and sell
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Tom Van Baak wrote:
>> Hi:
>> 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.
> Brooke,
> 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?
> /tvb
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