Hi The "how long can I go?" part of the question goes immediately to "how good do I want?". For a good confidence level, you might want 100 samples at your longest Tau rather than 5... For long Tau, that can indeed get pretty nasty. 100 samples at 10,000 seconds is a very long time. It is worth keeping in mind when you look at most plots. The confidence drops off significantly at the longer Tau.
Bob -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Tom Van Baak Sent: Monday, August 15, 2011 11:42 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] frequency stabilty question > Is it correct to assume that if you collect data every 10 ms for > 10 seconds (1000 data points in total), you could actually split > that data set into 100 sets of data at 1 seconds for 10 seconds > (10 data points in each set), which would have the same statistical > quality (I am sure caveats would apply) as a single data set of > 1000 data points collected at one second interval over a total > period of 1,000 seconds? > > Didier KO4BB If you look every 10 ms and collect data for 10 seconds you will be able to make a log-log ADEV plot for points from 0.01 s to 2 seconds, no more, no less. In order to plot ADEV points less than tau 0.01 s you need to re-measure using an instrument that gives data faster than one every 10 ms. In order to plot ADEV points more than tau 2 seconds you simply need to let the measurement run much longer than 10 seconds. For example, if you measure for 4 or 5 hours then you can plot ADEV out to 1 hour. In other words, the leftmost point on any log-log ADEV plot is determined by how *fast* you can collect data and the rightmost point is determined by how *long* you collect data. /tvb _______________________________________________ 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.
