[time-nuts] Thinking outside the box a super reference
brooke at pacific.net
Thu Nov 3 23:36:07 EDT 2016
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.
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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