It looks like there is a need for more tools to not only modify the data but to analyse the raw data to measure parameters like linear and logarithmic drift. I guess plain old statistics should give this sort of information.
73, Steve 2009/4/10 Tom Van Baak <[email protected]>: >> Steve >> >> Just dont get too carried away. >> Remember that the Hadamard deviation is only insensitive to linear >> frequency drift. >> If the drift is quadratic for example then it will affect the Hadamard >> deviation. >> >> Bruce > > Correct. This is another reason why the practice of removing > systematic drift from raw data first and then computing ADEV > on the residuals is quite useful. > > It allows you to separate the task of modeling systematic effects > from the calculation of stability (ADEV) of the residuals. > > For example, you may suspect ahead of time, or you may find > through analysis, that your DUT is following a slow logarithmic > drift trend rather than just linear drift. Either way, you can remove > the systematic effect to get to a closer measure of the intrinsic > stability limits of the DUT. > > This is common with OCXO which have aged, say more than > a few days, but less than a few months. It's pretty cool to see > very linear drift rates each day, but to also notice that the rate > itself slowly decreases week by week. > > As another example, you may find a strong correlation between > temperature and frequency. You could plot ADEV of the raw > data, and then plot ADEV of the temperature compensated > residuals and observe the difference in the plots. > > /tvb > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > -- Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW Omnium finis imminet _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
