[time-nuts] Z3801A

[SAIDJACK at aol.com]

Hi Tom,
 
we mesaured an early Fury prototype against a PRS10 using the  TSC5120A with 
an external 5MHz MTI 260 type free-running OCXO as  a reference. The Fury was 
significantly better <100s against the MTI  reference than the PRS10 was 
against the MTI ref, almost a factor of 10x better  1s to 10s.
 
This was due to the fact that the PRS10 has a large Rb  control-loop hump 
around 20s.
 
Above several 100s, the free-running 260 Oscillator was drifting away to  
make the measurements meaningless unfortunately.
 
On the long term internal TIM measurements, as stated below we are  basically 
getting to be within parts of 1E-014 of the M12+. As stated that is  
basically limited by the accuracy of the M12+ receiver itself. We are now  qualifying 
the absolute accuracy of the unit against a Cs standard to see how  good the 
M12+ and our OCXO can get.
 
bye,
Said
 
In a message dated 11/12/2006 13:54:34 Pacific Standard Time,  
tvb at leapsecond.com writes:

> Hi  Rick, Jose, Hmurray,
>
> forgot to mention:
>
> the  Fury unit only uses about 0.35A at 12V, and runs from 11V to 14V,   so
it
> can easily be run from a Pb battery, < 4.5W power  consumption. 45min
warmup
> time typ. with the double-oven  OCXO.

Said, this is very nice. Well done.

> Better <100s  Allan Deviation stability than the PRS10 SRS Rb  standard.

Are  these SRS specs or an actual measurements?

> Allan Deviation of <  2E-14 with 18 hour averaging possible, see  attached
> Allan  Deviation plot (Vertical in Nanoseconds, double-oven  OCXO).
Basically
> that's the accuracy of it's internal M12+ Timing  GPS.

Careful - that plot is not the performance of your GPSDO.
It  looks more like a measure of internal jitter or something
rather than  external accuracy or frequency stability. I'll
take this offline with you.  It's misleading to claim or to think
you're getting 2e-14 @ 18h performance  out of an M12+.