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.
http://prc68.com/I/PRS10.shtml
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
receiver.
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
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
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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