The data I posted came from a 10 hour run collecting data every second. I could certainly set up other longer experiments.
We quickly arrive at the limits of my experience...I had never looked at Hadamard deviation before. I was curious to see what I could learn about the Tbolt without having anything better to measure it against. For the time being, this is my "lab" reference. Let me see whether I understand what I've measured. The Allan intercept for my tbolt's undisciplined oscillator as measured by the onboard GPS solution is on order tau=800s. The Hadamard intercept under the same conditions appears to be more like 1600s. Does that tell me that if the disciplining model includes a drift compensation, the optimal disciplining time constant is close to the Hadamard intercept tau, but if there were no drift model, the Allan intercept would be more appropriate? And a primer or reference to the other statistical measures you mentioned (Theo_1, etc.) would be appreciated. --bruce W1BW On Mon, Jan 26, 2009 at 3:36 PM, Bruce Griffiths <[email protected]> wrote: > > Bruce > > What was the record length? > > TOTDEV and TOTHadamard should give more reliable estimates over a > greater tau range. > > Bias corrected Theo_1 and the Hadamard equivalent should be even better > at longer tau. > > Bruce > > Bruce Walker wrote: > > Thanks for the suggestion. Here is a composite plot with Allan and Hadamard > > deviations for my tbolt run last night with disciplining disabled. I think > > I computed Hadamard correctly. > > > > OADEV (blue) has a minimum of 9.6e-12 around tau=790 > > OHDEV (red) has a minimum of 4.9e-12 around tau=1660 > > > > --bruce W1BW > > > > > > On Mon, Jan 26, 2009 at 2:05 PM, Bruce Griffiths <[email protected] > > > >> wrote: > >> > > > > > >> Some idea of the shift in the minimum can be gleaned by plotting the > >> Hadamard deviation vs tau. > >> > >> Bruce Walker wrote: > >> > >>> I ran the same test as Bruce Griffiths on my tbolt; that is, I turned off > >>> osc disciplining altogether and created an OADEV plot from the internal > >>> phase measurements taken from its GPS solution. The plot is attached. > >>> > >> It > >> > >>> has a minimum of about 1e-11 at tau=800, and it has the sane general > >>> > >> shape > >> > >>> as Griffiths'. > >>> > >>> The next experiment I plan to do is to repeat the same thing using manual > >>> holdover mode rather than "Disable disciplining". That should continue > >>> > >> to > >> > >>> try to compensate for temperature and long-term drift (just not steered > >>> > >> by > >> > >>> GPS), whereas the data taken last night use a fixed DAC. > >>> > >>> --bruce W1BW > >>> > >>> > >>> > > > _______________________________________________ > 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.
