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

Tom Van Baak tvb at leapsecond.com
Wed Jun 28 23:00:50 EDT 2006

> My question exactly. I just talked to someone who uses
> SRS PRS10  Rb's, and apparently SRS admitted to him
> that the <10s ADEV is fairly  bad on the PRS10 units
> (without any details).

I very much agree with his report, although it's not
like SRS is trying to hide anything. Look again at the
PRS10 specs and nice composite ADEV plot at:
and see <2e-11 @1s; <1e-11 @10s; <2e-12 @100s

So I'm curious what sort of short-term performance
you or others are _expecting_ out of a PRS10, or
any low-cost, compact, telecom-market Rb standard
for that matter?

True, Rb have low drift and Cs have no drift but if
you want really good short-term stability use an
OCXO, or at least a lab-grade rubidium (like an
hp 5065A, about ~5x better than PRS10 at 1s).

For a GPSDO, Rb has very good price and holdover
performance relative to cesium or quartz. And you
can use a much longer GPS time constant with Rb
or Cs. However, if long-term holdover is not a key
spec for you; if you're after exceptional short-term
performance, then a high-end OCXO is probably a
better choice than a low-end Rb.

What makes the PRS10 a really nice unit is the
combination of good performance and a huge set
of RS232-accessible irresistible functionality.


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