The system does consistently come to lock with a constant offset. So its finding something. Just the odd little offset thats bugging me.
On Sat, Dec 6, 2014 at 2:48 PM, Magnus Danielson <mag...@rubidium.dyndns.org > wrote: > It's a challenge indeed. IF you are running on fumes, it will be harder > for the automatic locking to find first and second modulations, and if it > does this, it is much more likely to be the central pedestal as the others > will be even further down into the noise. The lack of the fundamental tone > will cause that FLL may fail to lock, since the sweep signal can be too > strongs, and if it does lock, it will be weak as the loop gain will be off > by the lack of signal and then naturally the S/N will be problematic. > > Not sure that it in itself will be the cause of systematically drifting of > the mark, but rather varying a lot around that mark. > > Cheers, > Magnus > > > On 12/06/2014 08:16 PM, paul swed wrote: > >> All good answers with a good tube and enough current to read on the meter. >> But I am working at the very limit of the Cs fumes. There is current, >> about >> .5 to 1 tick mark on the meter of a 5061 using a 5060 tube. >> Thats the challenge on a very eol tube. >> Regards >> Paul. >> >> On Sat, Dec 6, 2014 at 1:56 PM, Magnus Danielson < >> mag...@rubidium.dyndns.org >> >>> wrote: >>> >> >> Tom, >>> >>> On 12/06/2014 06:04 PM, Tom Van Baak wrote: >>> >>> Paul, >>>> >>>> There are 7 peaks total, about 40 kHz apart (on my 5061A). If you're >>>> talking about just the central peak, there are two smaller peaks on >>>> either >>>> side, about 1 kHz apart. The exact value depends on internal magnetic >>>> field, which is specific to each beam tube design. >>>> >>>> For some measurements of all the peaks, have a look at: >>>> http://leapsecond.com/pages/cspeak/ >>>> >>>> >>> These are the 7 Zeeman pedestals, and on top of them you have the Ramsay >>> fringes. You can indeed lock onto the wrong Ramsey-fringe, but they too >>> have amplitude differences. For a normal tube, they are quite >>> significant, >>> but if you look at the Ramsay fringes on the NIST-F1, they are much >>> denser >>> and looses amplitude much slower, so you need to pay more details of >>> which >>> fringe you use. The density of the Ramsay fringes is due to the >>> observation >>> time, which has been one of the driving forces to develop hydrogen masers >>> and cesium fountains, but for a simple cesium tube, it's a few dm of >>> distance and the average speed of the cesium steam. >>> >>> You can play with the C-field in addition to playing with peaks: >>> >>>> http://leapsecond.com/images/cfield.gif (578 x 4610 pixels) >>>> >>>> >>> Which is a good illustration. It would be good. >>> >>> For more details search the archives for the word Zeeman. For example: >>> >>>> https://www.febo.com/pipermail/time-nuts/2005-April/018171.html >>>> >>>> A nice description from hp how a cesium beam standard works: >>>> http://leapsecond.com/museum/hp5062c/theory.htm >>>> >>>> >>> Do check the FTS-4065C manual as I just uploaded. Good complementary >>> information. >>> >>> Cheers, >>> Magnus >>> >>> _______________________________________________ >>> 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.
