Hi Back in the long ago, processing was expensive. Much of what we do goes back to that era and paradigm.
A bidirectional loop with smarts on both ends would make a lot of sense today. Spend $5 on each end and you can be sure of what's going on. Yell to higher authority if something didn't look right. If it's "your" connection (as it is for most simple timing links) send lots of data and average to improve the SNR. The added cost is nearly zero... Bob -----Original Message----- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: Thursday, February 23, 2012 9:37 AM To: time-nuts@febo.com Subject: Re: [time-nuts] Neutrinos not so fast? (defectove connector) 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.