From: "Tom Van Baak" <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Oops - wrong URL for tvb plot! Date: Tue, 10 Apr 2007 07:46:30 -0700 Message-ID: <[EMAIL PROTECTED]>
> >> Tom's (tvb) plot I referred to in a previous message is at > >> > >> http://www.leapsecond.com/pages/3gps/gps-adev-mdev.gif > >> > >> Sorry for the confusion. > > > > Phew, I was kind of worried there for a while. The ADEV plot showed three > > straight parallel lines with no tendendency to converge. > > > > Interesting to (finally) see MDEV used for this analysis. > > > > Cheers, > > Magnus > > Me too. Using ADEV to look at the three receivers seemed like > the obvious thing to do, but then Brooks suggested I look at > MDEV instead and I was very surprised, and pleased, to see > the result. It much better reflects what we all do with GPS > receivers, something Tom Clark first popularized with his VP > TAC a decade ago -- which is to time average the sawtooth > away [ OK, for the purists: not to average away to zero, but > to reduce it somewhat through short-term averaging ]. > > The other thing about the plot is that it show a nice real world > example where using ADEV doesn't convey the right message > at all; using MDEV is closer to the truth. Indeed. I have long wondered why you guys are not using MDEV or at least ADEV and MDEV. Did you drift-rate compensate the measures before ADEV/MDEV them? That's another real world effect one may need to handle. For GPS receivers against a good reference (H/CS) it may not be such a big issue thought. It should be interesting to pull the drift rate values out and plot them alongside to see when they take over. Cheers, Magnus _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
