[time-nuts] oscillators

WB6BNQ wb6bnq at cox.net
Tue Aug 28 06:45:29 UTC 2012


That is a big no !  What the Thunderbolt is doing is adjusting the OCXO to keep
it aligned with a known reference from the GPS system.  The fact that a
microprocessor is involved is from a totally different perspective.

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 range.

A microprocessor controlled XO system allows for using cheap crystals with
minimum processing time and costs.  Because of limited storage space there is no
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.


Chris Albertson wrote:

> On Mon, Aug 27, 2012 at 7:33 PM, Jim Lux <jimlux at earthlink.net> wrote:
> > On 8/27/12 4:15 PM, Rick Karlquist wrote:
> >
> >> Several decades ago, the concept of the "smart clock" arose
> >> at what was then HP.  The idea was as discussed here to
> >> "characterize" past aging, "predict" future aging, and
> >> then "correct" the aging.
> >>
> >
> We know what a OCXO is and a TCXO is.  I was at a presentation at work a
> whike back and they called what you describe a "MPCXO"  or MicroProcessor
> Compensated XO.    They said the characteristics were between the OCXO and
> Doesn't the thunderbolt do this.  I think it watches the aging rate of the
> OCXO and adjusts during hold over.
> --
> Chris Albertson
> Redondo Beach, California
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