); SAEximRunCond expanded to false Errors-To: [EMAIL PROTECTED] RETRY A lot of work has been done in this area under the designator "Microprocessor Controlled Crystal Oscillator" MCXO, which is probably not a really great name. Anyway, they are non ovenized and use SC cuts. I believe the original FCS paper on them was around 1990.
Regarding turnover specifically: many 10811 crystals do not have turnovers. Instead they have a broad range of very low (but not zero) tempco. There is nothing magic about being at a turnover other than zero tempco. Rick Karlquist N6RK Murray Greenman wrote: > ); SAEximRunCond expanded to false > Errors-To: time-nuts-bounces+richard > Hi, > > When comparing with AT-cut, we all know that the SC-cut crystal gives > better warmup without overshoot, better 2nd order temperature performance, > fewer dips, lower acceleration sensitivity and better short-term > stability. However, nothing's been said in any of the literature I've seen > whether this depends on running the crystal at/near a turnover point, or > whether these advantages APPLY AT ALL TEMPERATURES. > > I am particularly interested in post-correction by electronic means in low > power applications, rather than temperature compensation (TCXO), as an > uncompensated oscillator tends to have lower phase noise and is cheaper to > make. In some applications (such as the one of interest here), absolute > oscillator frequency is unimportant, but knowing all about its > environmental behaviour is important. The biggest problem with using a > polynomial temperature fit approach is that with an AT-cut crystal, it is > very difficult to mathematically correct for the second order temperature > effects. > > Would using an SC-cut crystal in this type of application provide a > measure of freedom from second order temperature and acceleration effects > over a wide (-40°C to +85°C) temperature range, or does it only apply at > or near turnover? > > Regards, > Murray Greenman > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
