[time-nuts] Some results of PRS10 and Trimble Resolution T

Tom Van Baak tvb at leapsecond.com
Fri Jun 30 01:48:50 EDT 2006

> Hi Tom,
> The reason I investigated this is that I needed
> a very good (<2E-012 @ 1s) short term ADEV
> reference to measure the performance of our
> GPSDO (which is around 2E-012 at 1 second
> as you know :) on the TSC5120A.
> I found that I could use the MTI 260 reference from
> TSC for this purpose up to about 50s intervalls,
> then switch to the Rb above 50s.

Right. Depending on the UUT I sometimes do this too.

> They both have their strengths depending on the
> measurement intervall.

Yes, and this is true in general. It is not uncommon
to have to use two different references at two different
times to cover the range of tau you want to measure.

> It would make sense to slave an MTI 260 OCXO
> to a PRS10 with a PLL lock time of about 20s.
> This would generate a very clean output -  the
> Phase noise of the 260 is better than the PRS10,
> as well as the ADEV <20s would be improved.

Well, you can try this, and I know what you're saying,
but in my book it is more reliable and easier to make
two runs; one with each pure clean reference standard
rather than create (and debug, and trust) a noisy hybrid
of the two references to make one run. For some tau
in the middle the hybrid must always have more noise
than one of the two references so I say just skip the
hybrid and use each reference for the range of tau that
it excels.


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