In a message dated 4/10/2007 18:44:58 Pacific Daylight Time, [EMAIL PROTECTED] writes:
Knowing or calculating the sample rate is useful: 15-20 samples/second seems OK for a 53132. But if you were to measure it you would come up with a more exact number. One way to do this is time the collection of 1000 samples. Hello Tom, (BTW - I don't like the reply feature of AOL, I can't keep your original post prefixed with > etc. I think part of the reason is that the HTML stuff get's deleted by the server). Thanks for the info. I did do what you suggested, and I get 22.74 samples per second free-running over several hours. That makes the 0.1s Tau look nice. When using the timers' internal delay of 0.1s, I would expect the result to be slightly skewed, 1s + 50ns on average I would think since the measurement period has to be added as well? Presently, I am doing cross-correlation measurements using the 53132A: * Fury GPSDO (single AT-cut OCXO) against my FTS-4050 Cs * one Fury AT-cut GPSDO against our Fury Rubidium prototype (our secret project using a low-cost Russian Rb as the Fury OCXO) * Fury Rb against PRS-10 Rb, PRS-10 is GPS disciplined as well with ca. 7 hour time constant * PRS-10 Rb against FTS-4050 Cs. * Fury double-oven SC-cut unit against the best of all other oscillators (tbd) I do have some preliminary data which is very interesting: * The counter noise is dominant below 1s as you had mentioned. How can I do 0.001s measurements with such a noisy counter? * Our Fury Rubidium GPSDO prototype against the PRS-10 is the most stable combination, dropping below 1E-011 above 7s intervalls * The FTS-4050 is almost one magnitude more noisy than the Rubidiums at 100s intervalls. In fact it never catches the Rb's. I am a bit dissapointed by that. Of course it should be better long-term if GPS is completely turned off :) * All measurements get close to, or drop below 1E-012 at around 2000s intervalls (even the cheaper single-oven, AT-cut OCXO!). * The two Rubidiums drop below 1E-012 at around 1600 seconds. All measurements done using Ulrichs' Plotter ADEV utility. bye, Said ************************************** See what's free at http://www.aol.com. _______________________________________________ time-nuts mailing list time-nuts@febo.com https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts