-------- Matthias Welwarsky writes: > > My heuristic is that when you plot the histogram of the time between > > zero-crossings, you want the "bulge" on the low side of, but close to, > > the "allan-intercept" (Ie: where the OCXO and GPS allan curves cross.) > > > > If you are working with 3rd order PLLs (predicting frequency drift), > > plotting separate histograms of the duration of positive and negative > > phase inputs helps: The more they overlap, the better your drift estimate. > > That's an interesting metric, but just as well you could record the phase > error over a certain time and feed it into a linear regression solver.
Not even close. That will only give the (least-square) average, you *really* want to look at the curve-shape. > give you the drift in s/s and you want it to be 0 (or, like, close). You'll > know if your PLL is coupled too loosely if you see a drift. > Or, just look at the ADEV of the phase error. If the curve is going up > instead > of down, you know something's not quite right ;) Yes, but neither way are suitable metrics as input to an autotuning PLL. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com -- To unsubscribe send an email to time-nuts-le...@lists.febo.com To unsubscribe, go to and follow the instructions there.
