[time-nuts] Symmetricom SA22.c temperature sensitivity

Mark Sims holrum at hotmail.com
Sat Sep 2 18:23:58 EDT 2017

I connected a Tbolt to the 1PPS input of a Symmetricom SA22.c rubidium oscillator and ran Heather's software discipling code on it.   For some strange reason, you do get  better performance using a clean 1PPS rather than the crappiest one you can find ;-)

Anyway some interesting results came out.  White traces are the DDS frequency offset Heather is using to steer the SA22.c output freq,  yellow are temperature, magenta is the difference between the 1PPS in and 1PPS out (16.666 ns res of the SA22.c TIC).   The straight white and yellow traces are linear regression trend lines of those parameters.   A little math shows a clear dependence of the SA22 output freq on temperature of around 2.664E-11 parts per degree C.  This sort of agrees with a plot in the SA22.c data sheet that shows the TC vs ambient temperature... if "ambient temperature" means the baseplate temp reported by the unit.
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