This implies that in a Rb or Cs there is not a voltage reference source?
On Mon, Jul 17, 2017 at 3:49 AM, Bob kb8tq <kb...@n1k.org> wrote: > 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. _______________________________________________ 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.