[time-nuts] oscillators

Richard (Rick) Karlquist richard at karlquist.com
Thu Aug 30 03:45:02 UTC 2012

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

> 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

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