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. 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. Best regards Ulrich Bangert > -----Ursprungliche Nachricht----- > Von: [email protected] > [mailto:[email protected]] 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 <[email protected]>: > > 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 -- [email protected] > To unsubscribe, go to > 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.
