From: Magnus Danielson <[EMAIL PROTECTED]> Subject: Re: [time-nuts] Oops - wrong URL for tvb plot! Date: Tue, 10 Apr 2007 17:28:40 +0200 (CEST) Message-ID: <[EMAIL PROTECTED]>
> 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. Infact, if you send me the raw data I could process them and see what pops up. I have some code lying around already. Should get into the habit of doing some cheesy plots (gnuplot maybe). Cheers, Magnus _______________________________________________ time-nuts mailing list [email protected] https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
