So the way to eliminate that perturbation would be to put a copper jacket over it to attenuate the EM field?
André Esteves 2016-08-25 0:33 GMT+01:00 Bruce Griffiths <[email protected]>: > The Kerr effect is Proportional to the square of the field so one would > expect a strong 100Hz component from this. > > The magneto optical Kerr eefect which rotates the plane of polarisation is > linear however. > > Bruce > On Wednesday, August 24, 2016 07:04:31 AM Bob kb8tq wrote: >> Hi >> >> I would not rule out line noise into the electronic side of things. >> >> Bob >> >> > On Aug 23, 2016, at 7:06 PM, Magnus Danielson > <[email protected]> >> > wrote: >> > >> > Don't over-interpret the 50 Hz aspect, I don't remember those details > from >> > 4.5 months back or so, as I already indicated. I can ask on the details >> > tomorrow. I think they discussed the Kerr effect: >> > https://en.wikipedia.org/wiki/Kerr_effect >> > The PTB folks asked me the same question essentially. >> > >> > Would be nice to verify it. >> > >> > Cheers, >> > Magnus >> > >> >> On 08/24/2016 12:11 AM, David wrote: >> >> I could not find it in the links but Magnus mentions 50 Hz instead of >> >> 100 Hz. >> >> >> >> I would expect a 100 Hz noise signal if it was vibration coupled from >> >> magnetostriction in a transformer; magnetostrictive strain depends > on >> >> the magnitude of the magnetic field strength and not the sign which > is >> >> why 50/60 Hz transformers hum at 100/120 Hz. 50 Hz however fits > with >> >> piezomagnetism if the optical fiber was in an oscillating magnetic >> >> field and antiferromagnetic; for piezomagnetism, the strain does >> >> follow the sign. >> >> >> >> https://en.wikipedia.org/wiki/Magnetostriction >> >> https://en.wikipedia.org/wiki/Piezomagnetism >> >> >> >> I do not know if optical fibers are even slightly antiferromagnetic >> >> but maybe doping can make them susceptible? >> >> >> >>> On Wed, 24 Aug 2016 09:31:57 +1200, you wrote: >> >>> >> >>> What is the coupling mechanism giving rise to the 50Hz > disturbance? >> >>> DaveB, NZ >> >>> >> >>> ----- Original Message ----- >> >>> From: "Magnus Danielson" <[email protected]> >> >>> To: <[email protected]> >> >>> Cc: <[email protected]> >> >>> Sent: Wednesday, August 24, 2016 8:54 AM >> >>> Subject: Re: [time-nuts] Optical link connects atomic clocks over > 1400 >> >>> km of fibre >> >>> >> >>>> ... >> >>>> >> >>>> These links is in principle not very complex, but they are > regardless >> >>>> somewhat sensitive. One link experienced excessive 50 Hz > disturbance, >> >>>> which they could trace to the fact that for a short distance the > fibre >> >>>> was >> >>>> laying alongside the house 400V three-phase feed-cable with > quite a bit >> >>>> of >> >>>> current in it. >> >>>> >> >>>> ... >> >>>> >> >>>> Cheers, >> >>>> Magnus >> >> >> >> _______________________________________________ >> >> time-nuts mailing list -- [email protected] >> >> To unsubscribe, go to >> >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the >> >> instructions there. >> > >> > _______________________________________________ >> > time-nuts mailing list -- [email protected] >> > To unsubscribe, go to >> > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the >> > instructions there. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the >> instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
