> On Oct 5, 2016, at 4:52 PM, Bob Stewart <[email protected]> wrote: > > Hi Nick, > > Are you applying sawtooth correction to your phase measurement?
Yes, these are post-correction observations. I have some confidence that my corrections are scaled appropriately for the ADC values because of their stability “most” of the time (meanwhile, the uncorrected values are bouncing around inside a 12 ns corridor). > If not, are you merely seeing a hanging bridge that dissolves into at a > normal sort of tick-tock movement? > > Bob > > From: Nick Sayer via time-nuts <[email protected]> > To: Discussion of precise time and frequency measurement <[email protected]> > Sent: Wednesday, October 5, 2016 6:45 PM > Subject: [time-nuts] ADC sample voting algorithm? > > This is tangentially on topic, I suppose. It’s for my GPSDO. > > I notice periodically that the phase measurements seem “noisy.” You can see > that over the course of several seconds the value doesn’t change, then it > jumps a bunch and then comes right back. > > My theory at the moment is that sampling the ADC multiple times in a row > might help, but then what’s the best way to (quickly) pick which sample to > use? > > The mean would allow a bad sample undue influence. > > At the moment, I’ve coded taking 3 samples, averaging them and picking the > sample that is closest to the mean. If I’m right, and two of the samples > happen to be very close to each other and a third is an outlier, then that > seems like it would eliminate it. > > I guess what I want is the mode, but with 3 samples, that’s going to be > poorly defined (if at all). > > Anyone have any suggestions (besides a larger sample size)? > _______________________________________________ > time-nuts mailing list -- [email protected] <mailto:[email protected]> > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > <https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts> > and follow the instructions there. > > _______________________________________________ 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.
