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

[Joseph M Gwinn]

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-bounces at febo.com wrote on 02/22/2012 06:31:54 PM:

> From: Jim Palfreyman <jim77742 at gmail.com>
> To: richard at karlquist.com, Discussion of precise time and
> frequency measurement <time-nuts at febo.com>
> Date: 02/22/2012 06:32 PM
> Subject: Re: [time-nuts] Neutrinos not so fast? (defectove connector)
> Sent by: time-nuts-bounces at 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 <richard at 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-3875-43B2-8383-5CA2F86BE8E2 at 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
> > > phk at 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.
> > >
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> >
> >
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