HI This is a limitation on an OCXO based GPSDO. That’s really the bottom line here. It’s a limitation in an OCXO based part, but not in one based on an Rb or a Cs. If the added component costs far more than a Cs, it’s not an answer.
Bob > On Jul 16, 2017, at 7:25 PM, Chris Albertson <albertson.ch...@gmail.com> > wrote: > > What about josephson standards? After all, this is "Time Nuts" and we are > allowed to propose silly-complex solutions to simple problems if it > improves performance even a little. > > But seriously I thought the issue of making a perfect voltage standard was > solved because the Volt is defined to be whatever the Josephson array > produces. Yes expensive because to runs at nearly absolute zero. > > On Sun, Jul 16, 2017 at 4:10 PM, Bob kb8tq <kb...@n1k.org> wrote: > >> Hi >> >>> On Jul 16, 2017, at 6:33 PM, Richard (Rick) Karlquist < >> rich...@karlquist.com> wrote: >>> >>> >>> >>> On 7/16/2017 1:51 PM, Bob kb8tq wrote: >>>> Hi >>>> One gotcha with any ADC or DAC is going to be the reference. There, you >> are in the same >>>> “get what you pay for” dilemma. Stable and noisy, can do. Quiet and not >> very stable, can do. >>>> Both stable and quiet, not so easy if you want it cheap. >>>> Noise can also be the sigma delta ADC’s weak point. Even at slow rates, >> some of them need >>>> a lot of averages to quiet down. >>> >>> The reference initially used in the E1938A turned out to be too >> noisy/unstable. It was non trivial to find an upgrade. The >>> HP Smart Clocks of 20 years ago were limited in their performance >>> by the reference used. >>> >>> Has there been much improvement in references in the intervening >>> 20 years? >> >> They still don’t seem to have the hysteresis problem licked. Yes, you can >> do an oversized reference >> and take care of the issue. More or less that’s what you would have done >> 20 years ago. >> >> Bob >> >> >>> >>> Rick N6RK >> >> _______________________________________________ >> 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. >> > > > > -- > > Chris Albertson > Redondo Beach, California > _______________________________________________ > 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.