[time-nuts] Thinking outside the box a super reference

Brooke Clarke brooke at pacific.net
Thu Nov 3 23:36:07 EDT 2016

Hi Bert:

Have you looked into the Stanford Research PRS-10?  It a current production Rb standard with internal provision to sync 
to 1 PPS.
You can choose to run it like a GPSDO but it needs an external 1 PPS for that (there is no GPS receiver in the PRS-10).  
Or, you can time stamp an external 1 PPS.

The company was founded by a physicist and they hire mostly physicists rather than engineers.  I like their stuff.
The crystal oscillator in the PRS-10 is the SC-10, also made by SR and comes in many flavors that among other things 
trade off aging for stability.  I assume you could order a custom PRS-10 with the desired crystal oscillator specs.

Before spending a lot of money you might want to experiment with the PRS-10 and the best currently available GNS timing 

I experimented with both hardware and software sawtooth correction and they both have pluses and minuses.  I seem to 
remember that CNS Systems had a sawtooth corrected GPS timing receiver that ran TAC32 software, but haven't kept up on it.

Have Fun,

Brooke Clarke
The lesser of evils is still evil.

-------- Original Message --------
> Over the past there has been talk about building from  scratch high
> performance references. I think consensus was that it is out of  reach. In the mean
> time Corby is reworking an active maser which takes a lot of  know how. But
> let us look at his work on the super HP5065. It is able to  outperform a
> passive maser in the below 100 second range! Long term a proper  GPSDO should
> be possible to step in. We are working on it including pressure and
> temperature control. To make full use of it you also need to have the capability
> to monitor, record and analyze on a continuous basis preferably with out
> tying  up expensive equipment. We have the pieces in place and looking forward
> of  combining all the pieces and compare with Corby’s active Maser. We are
> back to  the GPSDO after being distracted by Tbolt performance. A third party
> is working  combining the GPSDO data stream with the data from the unit that
> generates  frequency, pressure and temperature data along with time to a
> USB stick, while  also be able to monitor with a PC.
> I know it is considered by some heresy but our lack of a  Maser and in Juerg
> ’s case no access to one, we try to overcome it with a GPSDO  tailored for
> Rb and Cs and control our Cs’s C field .
> There was a time that I did have a HP5065A but got rid of  it when I got
> some Cs’s. My best counter was A HP5345 and even with a Tracor 527  1 second
> performance was not an issue. That changed when Corby introduced me to  time
> nuts and frankly it was the first  time I learned about ADEV. But the
> HP5065A was gone. Now I have a cell  that Corby has plotted and time permitting
> may become a project.
> Let me get to the real issue. There are not enough  HP5065A’s out there and
> not affordable for all time nuts. Most are being kept  and are not for
> sale. But if a combined effort by many time nuts it MAY be  possible to recreate
> the guts of the HP5065A. The key word is MAY. 200 time nuts  be willing to
> invest $ 5000 each may get us there. The market does not justify  such an
> effort but time nuts keep bringing up discussions. All the other ideas  kicked
> around in the past will cost more. There are some among us that know what
> it cost and who can make the key elements like lamps, cells, filters etc.
> Just a  thought outside the box and hopefully may turn in to a limited
> constructive  dialog. We will continue on our path, which include FRK/M100, HP5065
> and  Cs.
> We would not be capable to contribute technically on the  physics package
> but I would be willing to contribute financially and with  monitoring
> equipment even if I would not be around when finished.
> Bert Kehren
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