Does anyone know about what technology is used in Swiss watches to get much better performance from their xtals than you might expect? I assumed that they had look up lists to insert extra counts to compensate for ambient variations, but I have never heard any details. cheers, Neville Michie
On 30/08/2012, at 1:45 PM, Richard (Rick) Karlquist wrote: > > On 8/27/2012 11:45 PM, WB6BNQ wrote: >> >> >> A microprocessor controlled XO is a non oven crystal oscillator system that >> has >> additional computational control providing a bit more than just mere passive >> temperature compensation. The additional computational capability deals with >> having coefficients of that particular oscillator's behavior pre coded to >> compensate for the nonlinear behavior over a given temperature rang > > It doesn't use coefficients. It has a look up table of frequency vs > temperature. > >> >> A microprocessor controlled XO system allows for using cheap crystals with >> minimum processing time and costs. Because of limited storage space there >> is no > > No it doesn't use a cheap crystal. It uses a *special* SC cut crystal. > This crystal could very easily cost more than an OCXO crystal. > >> way for the system to have enough data to even try to compete with the >> quality of >> a decent OCXO. Beyond its initial calibration setup, it has no way of >> keeping it >> tied to a known reference, like the Thunderbolt is doing. >> >> Bill....WB6BNQ > > An MCXO is a very good, but expensive TCXO. Only temperature, not aging is > corrected. > > It has nothing to do with "smart clocks". > > Rick Karlquist 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. _______________________________________________ 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.