Hi Bob, they should and do, and if it jumps the Rb will pull-in the OCXO frequency correcting for the error. This pull in time is determined by the loop time (cut-off frequency) of the Rb PLL loop. I expect this loop time to be much shorter than a GPSDO's loop time, so the effect is probably much less visible. One should still be able to see it as a distinct offset when plotting the EFC control voltage of the OCXO. Considering that jumps often hit 1ppb offset, I am surprised how many folks on this forum have discussed that their oscillators jump, and how little research actually has gone into figuring out how to minimize these jumps. I would not be a big fan of contraptions that use two or three OCXO's to minimize the impact since all three could potentially jump at the same time. I would rather attack the problem at the source - most of the time its the crystal. There is probably something that can be done to minimize jumps, such as the crystal cut, modifying the crystal operating temperature, modifying the current through the crystal, comparing different mounting methods, changing the direction (orientation) the crystal is mounted in, etc etc. Here is a hint for experimentation: I once had an OCXO that jumped all the time (many times per hour). Since this was a reject part (definitely a factory RMA), I took a large screwdriver and gave the OCXO a good bang. The jumping was immediately mitigated down to a couple of times per day. That causality was a real eye opener, whatever stresses were on the crystal were released by the shock. bye, Said In a message dated 10/23/2008 08:39:18 Pacific Daylight Time, [EMAIL PROTECTED] writes:
So why would they not show the same kind of jumps as plain OCXO's? Rick K. mentioned atomic standards avoid jumps. Bob Q. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
