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.
