[time-nuts] Neutrinos not so fast? (defectove connector)

Jim Lux jimlux at earthlink.net
Thu Feb 23 14:36:33 UTC 2012

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 -?)

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