A possible mechanism occurs to me. High-precision GPS is very vulnerable to multipath errors. A loos connector will have a significant reflection. The reflected energy will propagate backwards, and be reflected off the transmitter output discontinuity, the twice-reflected energy propagating back to the receiver. The original and the triple-transit echo will add coherently (for the modulation, not the photons) in the receiver. This is a perfect multipath scenario. How long must the cable be? Depends on the relative strength of main signal and triple-transit echo.
Joe Gwinn time-nuts-boun...@febo.com wrote on 02/22/2012 06:31:54 PM: > From: Jim Palfreyman <jim77...@gmail.com> > To: rich...@karlquist.com, Discussion of precise time and > frequency measurement <time-nuts@febo.com> > Date: 02/22/2012 06:32 PM > Subject: Re: [time-nuts] Neutrinos not so fast? (defectove connector) > Sent by: time-nuts-boun...@febo.com > > Maybe the loose connector meant the clock at one end *never* synced with > the GPS and just happened to be 60ns fast. Tighten the connecter, clock > resyncs, problem solved. > > Jim > > > On 23 February 2012 09:57, Rick Karlquist <rich...@karlquist.com> wrote: > > > Maybe they checked the connector by replacing the whole > > fiber optic cable with a new one, and while doing that > > had the "oh sh.." moment of realizing the length of the > > old one was 20 meters different than it was supposed to be. > > I think this sort of thing has happened to all of us > > with significant experience. Or maybe the cable was marked > > with an incorrect length (not due to error by the experimenters) > > and they forgot "trust but verify". We've probably all > > gotten bit by that one as well. > > > > Rick > > > > > > Poul-Henning Kamp wrote: > > > In message > <9a458dba-3875-43b2-8383-5ca2f86be...@leapsecond.com>, "Tom > > Van > > > Baak > > > (lab)" writes: > > > > > >>Could be on the electrical side of the adapter, not the optical > > >>side. It's not impossible to get 60 ns of phase or trigger error > > >>with RF connectors. > > > > > > I don't buy that explanation. > > > > > > It's very hard to get 60 ns *consistent* phase or trigger error, > > > with any kind of connector, almost no matter how you go about it. > > > > > > 20m of extra fiber sounds *much* more plausible. > > > > > > Inventing an excuse about a loose connector to cover up the mistake > > > sounds even more plausible. > > > > > > You really don't want to defend your phd dissertation, being known > > > as the idiot who made a fool of both CERN and SanGrasso in one go. > > > > > > -- > > > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > > > p...@freebsd.org | TCP/IP since RFC 956 > > > FreeBSD committer | BSD since 4.3-tahoe > > > Never attribute to malice what can adequately be explained by > > > incompetence. > > > > > > _______________________________________________ > > > 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. > > > _______________________________________________ > 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.