Re: [ATM] Worm mounting

["Don Clement" <clement.focuser@verizon.net>]

> Agreed, smooth and linear are a fine place to start.   But we don't live
in a perfect world and electronic smarts can compensate for the jiggles,
wobbles and sags.
>

Dave,

Your are right, we don't live in a perfect world and electronics ain't
perfect either. If the open loop BW is not large enough and slew rate is not
fast enough of your electronics (negative feedback) to correct for the
jiggles, wobbles and sags, (transients) and you have nonlinear components in
your drive, then not only will there be the error from the original
transients, but you can also create additional errors or intermodulation
products.  Linear components do NOT produce modulation products. The open
loop BW and slew rate of the negative feedback in a telescope drive is
limited by large mechanical mass of the telescope  and slow response of the
ccd detectors used for guiding. One can increase the  open loop BW and slew
rate by using a lightweight tip-tilt mirror near the focal plane (AO7), but
the slow responding ccd detector is then the limiting factor. It might be
possible in further increase BW and slew rate with tip-tilt mirror by using
an image intensifier tube in front of  fast responding four-quadrant silicon
diode detector.



Don Clement

Running Springs, California



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