[time-nuts] Fury - Rubidium

Scott Mace smace at intt.net
Tue Jul 27 15:41:16 UTC 2010


I have done this with several LPRO-101, X72, and a FRS-C.  The FRS-C 
that I used was out of a Lucent RFG-RB box.  It had a hot TTL output 
that was causing issues with the Fury,  The level was the problem, not 
the ttl.  The EFC was hypersensitive, and it took a long time for the 
unit to settle down before the Fury would handle it.  Same thing with 
the LPRO, and X72, you have to wait for it settle for a week or so 
before it starts to work well if it's been off for a long time.  The X72 
was by far the worst, and it would jump from time to time, which would 
make the fury unhappy.  I didn't have a chassis that would fit the FRS-C 
and the fury, so I just went back to the LPRO.  The lpro-101 has been 
the best so far.  I put everything in a 1U chassis and placed it in the 
bottom of my rack away from the AC vent.

This is what I use with the LPRO-101.

dac gain: 1000
efc scale: 1.30
efc damping: 35
ocxo slope: positive
phaseco: 35

I test it by changing the antenna delay.  It should recover within a 
reasonable time.  Bumping the coarsedac is typically too much change and 
takes longer to recover.  I run it with a 20ns offset to my z3801a, and 
they always stay within 20ns of other.

I've had the Fury running for about 5400 hours since the last reboot, 
running v1.21 firmware.  It stays within +-10ns,  usually it's between 
+-5ns.  Over 24hrs, gpscon reports TI average 0.15 or so and stddev 
around 2.5ns.

	Scott

On 7/27/2010 9:07 AM, Brian Kirby wrote:
> Has anybody on the list interfaced a Fury GPS controller to a rubidium ?
>
> If you have, please advise the rubidium are using and your SERV:DACG ,
> SERV:EFCS , and SERV:EFCD settings.
>
> I am working with a FRS-C at the moment and I have not found the right
> combination to get a stable lock.
>
> Thanks - Brian KD4FM
>
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