Steve, > So why would my counter show any significant differences > between a 1 sec or 2 sec gate time?
suppose your source has a 0.5 Hz frequency modulation. Would you see it with 2 s gate time or a integer multiple of it? Would you notice it with 1 s gate time or an odd integer of it? > I've just done a Google search for "dead time correction > scheme" and I just turn up results relating to particle > physics where it seems measurements are unable to keep up > with the flow of data, hence the need to factor in the dead > time of system. Google for the STABLE32 manual. THIS literature will bring you a lot further, many well documented source examples in Forth and PL/1, hi. F.e. you may look here: http://www.wriley.com/ Best regards Ulrich Bangert > -----Ursprungliche Nachricht----- > Von: time-nuts-boun...@febo.com > [mailto:time-nuts-boun...@febo.com] Im Auftrag von Steve Rooke > Gesendet: Freitag, 10. April 2009 12:55 > An: Discussion of precise time and frequency measurement > Betreff: [!! SPAM] Re: [time-nuts] Characterising frequency standards > > > Ulrich, > > 2009/4/10 Ulrich Bangert <df...@ulrich-bangert.de>: > > Steve, > > > >> I think the penny has dropped now, thanks. It's > interesting that the > >> ADEV calculation still works even without continuous data > as all the > >> reading I have done has led me to belive this was sacrosanct. > > > > The penny may be falling but it is not completely dropped: > Of course > > you can feed your ADEV calculation with every second sample removed > > and setting Tau0 = 2. And of course you receive a result > that now is > > in "harmony" with your all samples / Tau0 = 1 s > computation. Had you > > done frequency measurements the reason for this appearant > "harmony" is > > that your counter does not show significant different behaviour > > whether set to 1 s gate time or alternate 2 second gate time. > > So why would my counter show any significant differences > between a 1 sec or 2 sec gate time? > > > Nevertheless leaving every second sample out is NOT exactly > the same > > as continous data with Tau0 = 2 s. Instead it is data with > Tau0 = 1 s > > and a DEAD TIME of 1s. There are dead time correction schemes > > available in the literature. > > I've just done a Google search for "dead time correction > scheme" and I just turn up results relating to particle > physics where it seems measurements are unable to keep up > with the flow of data, hence the need to factor in the dead > time of system. This form of application does not appear to > correlate with the measurement of plain oscillators. Yes > there is dead time, per say, but I fail to see how this can > detract significantly from continuous data given a sufficient > data set size (as for a total measurement time). > > I guess what we need is a real data set which would show that > this form of ADEV calculation produces incorrect results, IE. > the proof of the pudding is in the eating. > > 73, > Steve > > > Best regards > > Ulrich Bangert > > > >> -----Ursprungliche Nachricht----- > >> Von: time-nuts-boun...@febo.com > [mailto:time-nuts-boun...@febo.com] > >> Im Auftrag von Steve Rooke > >> Gesendet: Donnerstag, 9. April 2009 14:00 > >> An: Tom Van Baak; Discussion of precise time and frequency > >> measurement > >> Betreff: Re: [time-nuts] Characterising frequency standards > >> > >> > >> Tom, > >> > >> 2009/4/9 Tom Van Baak <t...@leapsecond.com>: > >> > The first argument to the adev1 program is the sampling > >> interval t0. > >> > The program doesn't know how far apart the input file > samples are > >> > taken so it is your job to specify this. The default is 1 second. > >> > > >> > If you have data taken one second apart then t0 = 1. > >> > If you have data taken two seconds apart then t0 = 2. > >> > If you have data taken 60 seconds apart then t0 = 60, etc. > >> > > >> > If, as in your case, you take raw one second data and > remove every > >> > other sample (a perfectly valid thing to do), then t0 = 2. > >> > > >> > Make sense now? It's still "continuous data" in the > sense that all > >> > measurements are a fixed interval apart. But in any ADEV > >> calculation > >> > you have to specify the raw data interval. > >> > >> I think the penny has dropped now, thanks. It's > interesting that the > >> ADEV calculation still works even without continuous data > as all the > >> reading I have done has led me to belive this was sacrosanct. > >> > >> What I now believe is that it's possible to measure oscillator > >> performance with less than optimal test gear. This will > enable me to > >> see the effects of any experiments I make in the future. > If you can't > >> measure it, how can you know that what your doing is good or bad. > >> > >> 73, > >> Steve > >> -- > >> Steve Rooke - ZL3TUV & G8KVD & JAKDTTNW > >> Omnium finis imminet > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > > > > > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > 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 -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.