[time-nuts] DC Voltage Ramp?

Tom Van Baak tvb at leapsecond.com
Sun Sep 4 02:57:39 EDT 2005

> The problem is coming up with the voltage ramp.  I hear that the Austron 
> 2010B Disciplined Oscillator has steps that are too crude.  Has anyone 
> come up with a viable way to do this

Actually, the finer your ramp the more hopeless
the idea becomes. If you can look closely enough
at the output of a quartz oscillator it wiggles and
wanders all over the place most of the time. It is
true that a well behaved oscillator will follow a
general "ageing rate" on average over the long-term.

But even if the frequency follows a nice ageing
curve over many weeks or months, it does not
also mean that it will follow the same smooth
looking curve from day to day, or hour to hour,
or minute to minute.

GPSDO or Cesium devices do more than just
correct oscillator drift. They make continuous
and dynamic adjustments for any phase and
frequency deviations in the quartz LO, regardless
of the underlying physical reason.

The 2010B is quite nice, really. The phase and
frequency steps it makes are infrequent and
their size is less than the short-term noise level
so you can't actually see the steps.


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