Hi Well ….
A reasonably good DOCXO will come in around 2x10^-10 over 0 to 70C. Over a typical 4 C “lab wander” you should see < 1x10^-11. After being on power for a month or three, aging should be below 1x10^-11 per day. ADEV wise, it should do better than the GPSDO …..parts in 10^-13 are not unusual at 10 seconds on a typical design. Bob > On Sep 11, 2020, at 3:35 AM, donald collie <[email protected]> wrote: > > Thankyou to all who responded. It looks as if 2 parts in 10^12 is about > what can be expected - certainly much better than the 1 part in 10^9 > available from a typical double ovened quartz crystal oscillator barefoot. > Cheers!...............................................................................................................................Donald > Brett Collie > > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> > Virus-free. > www.avast.com > <https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail> > <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> > > On Fri, Sep 11, 2020 at 1:15 AM Bob kb8tq <[email protected]> wrote: > >> Hi >> >> Maybe a good idea to “back up” a bit here: >> >> The most commonly plotted data for the performance of a GPSDO is ADEV. >> Very simply put, to do ADEV you take a series of readings at a specific >> time >> spacing ( called tau ). The delta frequency from one reading to the next >> is then >> computed. You take the standard deviation of that “delta” information. >> >> What you are looking at is the “good guess” at what the frequency will be >> in the >> next time slot, based on what it is in this time slot. This may or may not >> be what >> your system / measurement instruments are looking as a. spec. >> >> The big reason ADEV exists is that it is convergent. As you take more >> data, the >> results don’t move all over the place, they converge to a single value. >> Measure today, >> then measure tomorrow, you get pretty much the same number. >> >> You might want to know what the maximum frequency error compared to >> “absolutely >> correct” is in your 10 second time period. This is a measure that is >> non-convergent. The >> longer you collect the data, the bigger the number gets. Measure for an >> hour and you >> get a different number compared to measuring for a day. Measure today / >> measure >> tomorrow and you may get dramatically different results. >> >> This is not to say that nobody ever can know what the frequency is. Only >> that “max” is >> not a good limit for this sort of random fluctuation. Again, this is what >> drove the guys >> at NIST to come up with ADEV back in the 1960’s. It’s what keeps us using >> it as a >> means of comparison today. >> >> Bob >> >>> On Sep 9, 2020, at 7:04 PM, donald collie <[email protected]> >> wrote: >>> >>> Can any list member please tell me the "accuracy" that can be expected >> from >>> a typical GPSDO >>> over, say, a 10 second interval? I have several measuring instruments >>> connected to my Trimbal GPSDO, and would like to know what to expect. At >>> the moment I am guessing about 1 to 2 parts in 10^12. >>> >> Thankyou,................................................................................Donald >>> Brett Collie >>> >>> < >> https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail >>> >>> Virus-free. >>> www.avast.com >>> < >> https://www.avast.com/sig-email?utm_medium=email&utm_source=link&utm_campaign=sig-email&utm_content=webmail >>> >>> <#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
