[time-nuts] uC ADC resolution (was: Poor man's oven)

Poul-Henning Kamp phk at phk.freebsd.dk
Sat Jun 10 17:15:18 EDT 2017

In message <B90B65D3-5E09-4C1C-ADE1-100A0A26D418 at n1k.org>, Bob kb8tq writes:

>If you want the controller noise to *not* be the limiting factor at an ADEV floor of 1x10^-12, 
>that drives you to a noise floor of < 0.1 mK. You can then work through the various thermal 
>gains to come up with a level of DAC bits that you need. You could equally as well decide
>on a 1x10^-13 floor and / or might have a 1x10^-9 sensitivity. 

Which gets us back to what SRS does for low noise:

Implement the low noise stuff, the PI(D) loop, in analog, but
tune/calibrate/adjust the analog circuitry with DAC's set (infrequently)
by a uC.

Poul-Henning Kamp       | UNIX since Zilog Zeus 3.20
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