[time-nuts] LORAN C shutdown

[bg at lysator.liu.se]

> 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.

Most RLGs have a mechanical dither mechanism, but that is only moving the
optical subsystem within the gyro. There is no platform at all for the
accelerometers, and the three gyros typically do not use the same dither
frequency. There are RLGs (Litton/NGC Zero Lock Gyro) that have no
mechanical movement, they instead have an 'optical' dithering of one
mirrors.

FOGs have no moving parts at all.

> But that is a minor detail.

True.

> Poul-Henning

--

    Björn