[time-nuts] NCOCXO anyone?

Richard (Rick) Karlquist richard at karlquist.com
Thu Jul 21 21:47:24 EDT 2016

On 7/21/2016 4:56 PM, Nick Sayer via time-nuts wrote:
> Oh my. That’s a bit more than I was originally considering… What I had in mind was adding a DAC front end to an OCXO so that you could tune the EFC with serial commands rather than analog and calling that a product.

20 years ago when HP was working on a so called "smart clock"
GPS box, they decided to do what you said, use a DAC to
tune the EFC on the E1938A oscillator.  I
recommended to them NOT to try to do that, but they
didn't listen to me.  At that time, it
was nearly impossible to come up with a DAC, buffer
amplifier, and voltage reference that didn't degrade
the stability of the E1938A, which isn't even as stable
as a 10811.  What you need to ask yourself is:  in
2016, can I finally get analog components that are
an order of magnitude or two better than what was
available in 1996?  I don't know, without researching
it.  Certainly, we can't depend on Moore's law coming
to the rescue.  If anything, that works against analog
IC's by obsoleting older analog processes.

Also in 1996, phase microsteppers were already legacy
technology and didn't have a good reputation for spectral
purity.  Another non-panacea.


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