[time-nuts] CSAC Project(was CSAC purchase)

jimlux jimlux at earthlink.net
Thu Jan 25 15:31:42 EST 2018


On 1/25/18 9:39 AM, gandalfg8--- via time-nuts wrote:
> 
> 
> At the time of writing a copy is available here....
> 
> www.obsip.org/documents/Gardner_IEEE_Oceans_2016.pdf
> 


"While results from an early batch of CSACs have been largely positive, 
later units have not performed as well. The CSAC specifications have 
changed, reflecting a decrease in reliability and accuracy of more 
recent units."

no kidding - there's a well known issue when MicroSemi took over 
building CSACs from Symmetricom, these things (like many precision 
timing widgets) have a "recipe" and it's easy to "lose the recipe" or 
find that there's unexpected and unknown components to the recipe.

Take a look at data sheet revs for the CSAC.. full temp range, then all 
of a sudden around rev G or H, temperature range is quoted at 0-35C 
operating, *0-40C non-op*.  I asked the sales rep if they ship them with 
icepacks in styrofoam like mail order cheese in the summer - that UPS 
truck gets way over 40C inside.

As always, this was discussed on the list and is in the archives.

That being said, I have no complaints about Microsemi being forthcoming 
about the issue and helping us to understand the nature of the problem. 
And they claim to have fixed the problem.

Hopefully, this summer, I'll have some data from a "narrow temp range" 
CSAC against GPS 1pps in an environment where there's no gravitational 
effects, and fairly small temperature fluctuations.




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