Hi A clock and a hazmat site all rolled into one.....
Bob On Mar 5, 2010, at 2:41 PM, paul swed wrote: > OK then if you ground up cesium azide and put it in the hour glass wouldn't > you have a cesium clock at much lower cost (And accuracy) then an HP?? > Might last quite a while also. > > On Fri, Mar 5, 2010 at 1:53 PM, Tom Van Baak <[email protected]> wrote: > >> Even defining when the sand timer is "done" is not a real >>> simple thing. Waiting for that very last particle to drop may >>> not be the best approach. >>> Bob >>> >> >> Correct. Marking time with an hour glass is not that different >> from marking time with a 1PPS. Each signal has a rise time; >> one picks the appropriate live trigger level or sampled slope >> waveform model to minimize jitter. >> >> Waiting for the last grain is like waiting for the last millivolt of >> a TTL 1PPS pulse; no one does that. >> >> Note that [this] hourglass interval has a standard deviation on >> the order of 10 seconds. So my initial goal is 1 second timing >> resolution, which turns out to be pretty easy to do optically. >> >> Whether sand or cesium, phase comparators have a minimum >> resolution. While lower resolution is better, if the ADEV of the >> DUT is too far above the ADEV of the comparator then that >> resolution is wasted. So detection to a granularity of 1 second >> is sufficient for this application. >> >> >> /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. > _______________________________________________ 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.
