[time-nuts] Fwd: CS reservoir depletion

John Miles jmiles at pop.net
Mon Jan 17 01:03:13 UTC 2011

> We can see that the Fury actually out-performs the 5071A between 0.1s to
> 10s with quite a bit of margin. Then it is less than one order of
> magnitude
> difference between the two from 10s to about 40Ks, at which time the Fury
> seems  to "catch up" to the 5071A. The GPSDO likely also out-performs the
> 5071A in  terms of phase noise performance.
> There is about a 33x price difference between the two units new,  and as
> you mentioned the GPSDO is maintenance-free, whereas the 5071A
> requires  care
> from time to time. There is also a massive difference in
> power-consumption
> and thus operating costs.

The performance of the Fury looks great for an off-the-shelf unit.  My
tweaked 10811 Thunderbolt can beat it only under ideal conditions (i.e.,
cherry-picking from among multiple runs) and with the loop TC set to 1000

Is the raw data for the Fury and 5071A traces available?  The 5071A looks a
bit noisy, although it's still in spec.  You're winning the race between
t=0.1s to 10s because the 5071A seems to be using a shorter time constant
than is reasonable for disciplining a high-end 10811.

Interestingly, a 5061A with Tc=100s would have been pretty competitive with
the Fury in that test.  I'd be curious to plot the Fury data set next to the
ones that I keep around for reference.  (In this example, the blue trace is
the one Tom just posted for his 4-day Thunderbolt run, and the magenta one
is a weeklong run of my 5061A against his maser.)

-- john, KE5FX
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