OK, Yahoo has done it to me again. Sent to Tom direct and not to the list. So, repeated here:
Hi Tom, One of the biggest problems I've unwittingly faces is that of retrace. I had seen the term used several times, but hadn't looked it up until last night. As you can imagine, with a GPSDO under development I've had to remove power more than a few times to make hardware changes. I think the next time power is down I'm going to try to rearrange things so that the OCXO is permanently powered and just the board gets switched. But then again would big jumps in the EFC cause other problems that are almost as bad? There is just so much to learn to get this going; especially without either an engineering degree or experience in this field. Bob Camp is definitely right that you have to put your time in - lots of it. Bob - AE6RV ________________________________ From: Tom Van Baak <t...@leapsecond.com> To: Discussion of precise time and frequency measurement <time-nuts@febo.com> Sent: Monday, October 20, 2014 6:42 PM Subject: Re: [time-nuts] LTE-Lite module To add to Bert's note... Realize that for a GPSDO, (linear frequency) aging-per-day is irreverent, almost by definition. What matters is phase noise and short-term stability, neither of which you can possibly fix with disciplining against GPS. GPS takes care of the rest. Long-term stability can be critical for non-GPS applications, which is why oscillators with daily aging rates in the -11's and -12's are so amazing. Consider this: if you want to run your bench with a clean 10 MHz source, stable to 11 or 12 digits and accurate to 9 digits -- you may be much better off with a free-running, stand-alone OCXO with an aging rate down at 1e-11/day than using a GPSDO/TCXO. To maintain accuracy of your OCXO just re-tune your OCXO *once a year*. Aside from ADEV plots, this is another way to appreciate how amazing some OCXO are, any why many of us still troll eBay for high-stability, low-noise, low-drift quartz oscillators. /tvb ----- Original Message ----- From: "Bert Kehren via time-nuts" <time-nuts@febo.com> To: <time-nuts@febo.com> Sent: Monday, October 20, 2014 4:01 PM Subject: Re: [time-nuts] LTE-Lite module Allow me to clarify. I started out with 7 MV 89 one of it a total loss. The remaining 6 after 3 month + burn in show better than 1 E-11 aging per day, 2 closer to 5 E-12. Only two have been tested for ADEV and are close to 1 E-12, 2X not 10 X. Bert Kehren _______________________________________________ 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.
