[time-nuts] LORAN C shutdown
Magnus Danielson
magnus at rubidium.dyndns.org
Wed Nov 11 00:01:48 UTC 2009
Poul-Henning Kamp wrote:
> In message <2455.41.130.184.218.1257890017.squirrel at webmail.lysator.liu.se>, bg
> @lysator.liu.se writes:
>
>> High performance mechanical rotating gyros are associated with platform
>> systems. Ring laser gyros and fiber optic gyros are typically strapdown,
>> which completely dominate modern navigation.
>
> Actually, they are usually strapped down to a deliberately moving
> platform to avoid mode-lock-in at the mirrors, which produces a
> "sticky" or "discrete steps" effect at slow rates of rotation.
>
> But that is a minor detail.
While such laser gyros need to vibrate their mirrors to avoid the
locking (having heard the audioble noise out of Björns basement lab)
they remain part of the strap-down system. A little bit of vibration is
nothing to rotating objects.
There is also gyros having no vibration at all, but uses a roll of fiber
instead.
Cheers,
Magnus
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