Well, since they are above the atmosphere (or at least in a region where
the visibility is a constant), then thye don't have to do nearly as much
processing as one would think, but even then I've got to ahdn it to the
people who make it work.

Point a camera away from the earth - there will be several stars which are
brighter (and maybe color variations are used) than the rest.

At that point you can reference your real time clock (which is accurate)
compute the positions of the stars, match up the positions to get a 3d fix
on the camera, and then compute the earth's position and rotation (based
on the RTC), find the error in the inertial navigation and correct for it.

But image processing is probably the hardest part for me to
conceptualize.  Since the image is simply a black background with white
dots it should be significantly easier than, say, robot vision on earth.

-Adam

"Sean H. Breheny" wrote:
>
> Can anyone point me to more info on how they do star sighting? That seems
> to me to be a fairly difficult problem. It would be especially interesting
> to see how they solved it with 1950s or 60s electronics.
>
> Sean
>
> At 08:54 AM 2/8/01 -0800, you wrote:
> > >    Missiles that are only going to be fired on cloudless nights can
> > >    take star sightings.
> >
> >
> >They take the star sighting after they leave the atmosphere to correct for
> >errors in their inertial nav.
> >
> >John
> >
> >--
> >http://www.piclist.com hint: The PICList is archived three different
> >ways.  See http://www.piclist.com/#archives for details.
>
> --
> http://www.piclist.com hint: The PICList is archived three different
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