RESENT WITHOUT ATTACHMENTS
Fellow Timenuts, Here are the clues that will answer some of your questions concerning the newer version FEI Rubidiums and also its Kissing cousins from Symmetricom; the newer series XPRO and SA22c. It appears both companies have came with up with same idea at the same time or copied each other to a large extent. In the old days the Atomic loop was in the analog domain. The loop output signal was a fixed frequency and any other frequency was derived from that fixed frequency outside of the loop. These newer devices have incorporated a different paradigm using a digital control process for the actual Atomic loop. Thus the output frequency is truly part of the loop rather then derived from the loop. The AD9832 provides but a fraction of the control loop error signal allowing for adjustments to be made in steps of parts in 10 to the minus 13 (10E-13). The C-field adjustment is done with either an A/D or some digital potentiometer, but may also have some possible external access. The end result is that the output frequency is factory selected by changing the frequency of the main crystal oscillator. This makes it very hard to change a Rubidium with an odd-ball frequency because of internal firmware. All of this is gleamed from two (albeit cryptic) documents from Symmetricom. One document is on their XPRO unit and the other is on the SA22c unit. In the XPRO document carefully read pages 15 through 19 (PDF pg 21-25). Then carefully read the SA22c document pages 20 and 21 (PDF same). Keep in mind that the info is written so as to not give away so-called trade secrets. So you have to do some critical thinking and reading between the lines to get the whole picture. The XPRO document block diagram on page 16 (PDF-pg 22) is the primary key to all of the above. I am including the two aforementioned documents as attachments. Hopefully they will get through. If not I will ask Didier (KO4BB) to host them on his site. Bill....WB6BNQ _______________________________________________ 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.