If dither is a consideration it will be the most critical test. Bert Kehren In a message dated 1/13/2012 12:52:16 P.M. Eastern Standard Time, lists@rtty.us writes: Hi Another thing that would need to be investigated - How fast (and how uniformly) does it respond to a frequency set command. If you dither, you care about how long it's at this or that frequency. Measuring 7x10^-13 frequency shifts on the unit probably isn't the best way to check that out .... Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of EWKehren@aol.com Sent: Friday, January 13, 2012 6:20 AM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Mechanical Question What we know is that you can set the Rb in 7 E-13. Dithering would allow even closer setting, the question is what rate will the Rb accept with out loosing lock or deterioration of the performance. Some one should explore that. I am still waiting to se some aging. Taking the 10 MHz output and than use an analog loop and something like a Morion OCXO and you have the best of all. Digitally controlling the Rb will cut the cost of the control loop in half. For $10 in parts and a PC board for less than $10 using Shera like controller can be realized. What is needed is some one able to do the PIC. If some one is interested and able, please contact me off list. A low cost GPS or a 1 pps output of a Tbolt be perfect source. Bert Kehren In a message dated 1/12/2012 12:20:15 P.M. Eastern Standard Time, lists@rtty.us writes: Hi I think it would be worth the effort to try dithering the DDS commands into the Rb while measuring ADEV. You *might* find that you can do it with little or no impact on the unit's stability. If so it takes out some modification effort and should make the controller cheaper. Bob -----Original Message----- From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On Behalf Of EWKehren@aol.com Sent: Thursday, January 12, 2012 10:43 AM To: time-nuts@febo.com Subject: Re: [time-nuts] FE-5680A Mechanical Question Bringing out the C field in my estimation does not effect long or short term. External magnetic field I think is a joke. An other option is a loop that generates a tuning word for the DDS but that means your steps are 7 E-13. Bert Kehren In a message dated 1/12/2012 10:34:10 A.M. Eastern Standard Time, davidwhess@gmail.com writes: I was more interested in the technical details of how to adjust the output of a RbO without sacrificing the short and long term stability. I have seen a few designs that used a DDS to generate the 10 MHz output which lends itself to this but they all suffer from DDS and tuning noise. I see now that the RbO can be adjusted with an external magnetic field. On Thu, 12 Jan 2012 07:34:44 -0600, "J. L. Trantham" <jltran@att.net> wrote: >David, > >I have been following discussions on the list about a GPSDRbO for a year or >so. Some interesting challenges and probably best implemented in a 'stable' >environment rather than portable operation but as best I can tell, it would >require a very stable and good antenna location, stable and clean power, and >I was thinking of using something like an LPRO-101 with an Ext C Field >input, a Shera type controller, and a GPS timing receiver, though, I suspect >there are likely to be some 'multi-tasking' receivers out there that will >look at several sources including GPS, GLOSNASS, etc. > >While the project might be fun, for portable work, it is likely far easier >and probably just as good (almost), to use a Tbolt. > >In any event, something to think about for the future. > >Joe > >-----Original Message----- >From: time-nuts-bounces@febo.com [mailto:time-nuts-bounces@febo.com] On >Behalf Of David >Sent: Wednesday, January 11, 2012 11:12 PM >To: Discussion of precise time and frequency measurement >Subject: Re: [time-nuts] FE-5680A Mechanical Question > > >How would a GPSDRbO work? Phase lock the DDS output to the GPS? Phase lock >a VCXO to the GPS and then phase lock to the RbO on loss of GPS lock? > >On Wed, 11 Jan 2012 22:55:58 -0600, "J. L. Trantham" <jltran@att.net> >wrote: > >>Bill, Brian, Bill, and Peter, >> >>Thanks for the info. All I need now is a 'project' to incorporate the >>unit into. >> >>In the back of my mind, I have the thought of a 'box' that will be >>battery powered or 110 VAC powered (perhaps with an internal SLA >>battery) and include a GPSDO and Rb unit (possibly a GPSDRbO) for the >>purpose of a 'reference' for portable operation in the microwave >>regions. > >_______________________________________________ >time-nuts mailing list -- time-nuts@febo.com >To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. > > >_______________________________________________ >time-nuts mailing list -- time-nuts@febo.com >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.