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.
