Gentlemen, first of all I would like to thank you for your feedback.
Reading in the literature that some of you supplied revealed that modern counters may work even more tricky than i had though but that their "tricky output" is NOT easily taken as the input for AD computations without additional precautions. > The Ref Output on the front panel of the SR620 is derived > (1/10,000) from the > EXT IN on the rear panel. So when you apply a 10 MHz signal > to EXT IN you get > a 1 kHz REF OUT. Appendix B in the PSR10 Rubidium source > manual describes how > to use this along with the arming function to average 1,000 > measurements per > second resulting in 2E-12 per second on the display. i.e. > very close to the > HP53132A. So no external hardware is required and no PC to > get this result. After I had read this suggestion of Brooke I immediately gave it a test. With a reference and a DUT both believed (due to other experiements/measurements) to be stable < 3E-12 @ 1s I received the results attached. And of course you do not get a frequency value as > second resulting in 2E-12 per second on the display may indicate. The counter works in time interval mode in this arrangement and you get 1 s data of delta ts between 0 and 100 ns that need to be un-wrapped. I would judge that this method is well suited if a DUT needs to be trimmed to 10 NHz with high resolution but I fear that it does not help us in high stability measurements since the intrinsic noise is still more than a decade too high. Best regards Ulrich Bangert > -----Ursprungliche Nachricht----- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Brooke Clarke > Gesendet: Mittwoch, 8. Oktober 2008 23:43 > An: Discussion of precise time and frequency measurement > Betreff: Re: [time-nuts] What is the best counter for a Time Nuts? > > > Hi Bruce: > > The Ref Output on the front panel of the SR620 is derived > (1/10,000) from the > EXT IN on the rear panel. So when you apply a 10 MHz signal > to EXT IN you get > a 1 kHz REF OUT. Appendix B in the PSR10 Rubidium source > manual describes how > to use this along with the arming function to average 1,000 > measurements per > second resulting in 2E-12 per second on the display. i.e. > very close to the > HP53132A. So no external hardware is required and no PC to > get this result. > > Have Fun, > > Brooke Clarke > http://www.prc68.com > http://www.precisionclock.com > > > Bruce Griffiths wrote: > ..... > > > > It is also possible to use a SR620 or a 5370 to take 1000 > > timestamps/sec. However may require using some external hardware > > (frequency divider). For maximum accuracy and precision the > resultant > > data has to be logged and processed off line using a PC or other > > computer. > > > > > _______________________________________________ > 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. >
SR620.pdf
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