[time-nuts] using Fury GPSDO with Rb

SAIDJACK at aol.com SAIDJACK at aol.com
Mon Apr 7 04:38:52 EDT 2008

Hi Scott,
let me reply on this list since other users are also using Rb's.
Here is a quick pointer:
1) determine EFC slope of Rb (pos = frequency goes higher with higher  EFC 
voltage). Set the slope with serv:efc:slop [positive/negative]
2) Determine maximum frequency deviation at EFC = 0V (serv:coarsedac 0)  
using a frequency counter
3) Determine maximum frequency deviation at EFC = 5V (serv:coarsedac  255)

4) Set Dacgain according to table in user manual depending on the frequency  
difference between 2) and 3)
5) Set Integral part of loop to zero: serv:phaseco 0.0, this helps for  now
6) Set Proportional part of loop to a number that makes the unit lock as  
quickly as desired without oscillation and overshoot (for example:  serv:efcs 1.0 
to serv:efcs 6.0
7) Set the integral part of the loop so that the phase is driven to 0ns UTC  
offset as quickly as desired without overshoot/oscillation, for example:  
serv:phaseco 20.
Repeat 6) and 7) after some hours.
Hope that helps,
> -----Original Message-----
> From: Scott Mace
> Sent:  Saturday, April 05, 2008 17:51
> To: Said Jackson
> Subject: Re:  Fury GPSDO
> Said,  I finally got my fury up and  running, I'm using a efratom 
> FRS-A and also a LPRO-101.
> Do you  have any recommending starting points for tuning the servo 
> for a  rubidium unit?
>  Scott

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