And by using a differential pair is like halving the rise time: when one arm rises the other falls, effectively doubling the speed of the crossing and the sharpening of the trigger event. Sort of auto_ schmitt_trigger...
On Thu, Feb 23, 2012 at 3:45 PM, Azelio Boriani <azelio.bori...@screen.it>wrote: > I recommend the differential pair: here the trigger have to sense the > crossing of the two signals and this crossing is well definite. > > > On Thu, Feb 23, 2012 at 3:36 PM, Jim Lux <jim...@earthlink.net> wrote: > >> On 2/23/12 6:24 AM, Alberto di Bene wrote: >> >>> On 2/23/2012 1:04 AM, Poul-Henning Kamp wrote: >>> >>> I simply don't buy the story that tightening the connector makes >>> a consistent 60 nanoseconds difference on a signal. >>> >>> I spoke with a physicist of Cern, friend of the leader of the team >>> that >>> performed the Opera experiment. >>> He told me that the badly seated connector caused the amplitude of the >>> signal to be lower, and for this reason the trigger point, which was >>> set at a specific level, was reached 60ns later. >>> 73 Alberto I2PHD >>> >> >> >> >> Darn those finite rise times<grin> >> I've been bitten more than once by this very phenomenon (which I admit >> doesn't say a lot for me.. being bitten once is ok, but since I've had >> multiple bites...) >> >> But this brings up an interesting time-nut problem for the hive mind.. >> >> If you had to design some scheme for interconnecting "boxes" and wanted >> to transmit an accurate time sync, what should it look like, so that you're >> insensitive to things like rise time. >> >> (maybe this harkens back to the discussion about 10 MHz, why sine vs >> square wave distribution) >> >> It has to be a single signal (maybe a differential pair), because >> otherwise, don't you have potential for skew between the multiple signals. >> >> Zerocrossing sort of works, if you take only one direction, but does >> asymmetry of the waveform screw you up? (e.g. what's "zero".. is it half >> way between peak values + and -?) >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. >> > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.