[time-nuts] Optical link connects atomic clocks over 1400 km of fibre

Bob kb8tq kb8tq at n1k.org
Thu Aug 25 07:11:19 EDT 2016


There is also the minor issue of putting the (very thick) layers on in a spiral around the "core". You put one layer on clockwise and the next counter clockwise. Since the materials are quite springy, controlling the whole process through heat treating is a real chore.


> On Aug 25, 2016, at 4:25 AM, Poul-Henning Kamp <phk at phk.freebsd.dk> wrote:
> --------
> In message <1057836989.2088307.1472104857885.JavaMail.yahoo at mail.yahoo.com>, Br
> uce Griffiths writes:
>> You'd need a rather thick copper jacket to shield effectively
>> against the 50Hz magnetic field.
> As in: A good-sized fraction of the wavelength if I recall :-)
> Electric fields are so much easier...
> One interesting thing here is that across distances like this,
> there would be significant longitudal currents in such a shield.
> Not as bad as metal spanning the Mississippi, but getting there.
> -- 
> 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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