Thanks for the comments. I did a quick check of the noise floor of the 5370b while feeding the 10 mhz output of the tbolt to the start and stop inputs of the 5370b with a t connector. At a tau of 10 (approx 2.5 seconds) the Allan deviation is 1x10-11, at a tau of 100 (approx 25 seconds) it is 1 x 10-12. Optimizing the trigger settings might lower this some what but I used the same settings as before. I was not aware you need an instrument with a noise floor a couple of decades below the signals you are trying to measure. Sent from my iPad
On 2011-02-09, at 9:19 AM, "WarrenS" <[email protected]> wrote > Looks to be mostly a plot of the 5370B's noise floor at low taus. > You may need something a couple of decades better if you want to measure the > Tbolt at that tau setting. > > BTW, You should NOT set the TBolt's TC to >999 sec. I have found that the > control can become somewhat unpredictable, AKA S/W bug. > > ws > > ********************* > ----- Original Message ----- From: "Mark Spencer" <[email protected]> > To: <[email protected]> > Sent: Tuesday, February 08, 2011 7:48 PM > Subject: [time-nuts] Thunderbolt behaviour with long time constants. > > > First apologies for the zipped attachement. > > I thought some members of the mailing list might find the attached plot of the > performance of my Thunderbolt to be interesting. After looking at the > performance of my Thunderbolt with a time constant of 225 seconds which seems > to > > be about right for my Thunderbolt, I noticed that the Allan deviation appeared > to be be reduced at high values of Tau (approx 2,000 seconds..) > > I then changed the time constant of my Thunderbolt to 2,000 seconds and > compared > > the two plots. I'm quite surprised at the result and the similarity between > the peformance at low values of tau with the two different time constants. > I took 4 readings per second with a 5370B, hence each unit of tau on the graph > is approx .25 of a second. > > I'll likley try other time constants in the future > > _______________________________________________ > 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.
