Last updated: 30 November 2000

Autostar Drive Training Adjustment

Subject: Writeup on the "Flight to the Right" workaround.
From: horrox@HONet.com (Michael Rathbun)
I've had a couple more evenings to test and evaluate the results of feeding bogus information into the drive training algorithm to correct "Flight to the Right" Autostar/ETX behavior. I still see some unruly behavior at high magnification, but nothing approaching the magnitude of the original problem. At one point I moved Saturn to just left of center of FOV in a 9.7 mm EP and went in to supper. I returned 20 minutes later to find Saturn still there.


Some ETX/Autostar users see a condition in which attempting to move an object to the left in the FOV with the left arrow key results in the 'scope undoing the movement some ten or fifteen seconds later; in some cases the problem is so extreme that the final location of the object is further to the right than before the movement was attempted. The problem is practically nil near Polaris and becomes more pronounced as the telescope is aimed toward the celestial equator.

This condition appears to be related to azimuth backlash compensation routines in the Autostar and it is possible that it might be fixed by applying the "creep after beep" patch found here. I have not had a chance to load the patched binary and evaluate.

However, I have found that feeding a bit of incorrect information to the azimuth training routine will greatly reduce the problem.


1. Set up for azimuth training by placing your target object in the far left of the FOV rather than the center of the FOV.
2. For the first half of the training process, use the --> key to move the target back to its original far-left position.
3. For the second half of the training process, use the <-- key to move the target to a point to the right of the starting position. To begin with, try moving the target to the point midway between the center and the right edge of the FOV.

It will require some experimentation to determine how far to the right of the original target position you should move the target with the <-- key. Too far to the left and some vestige of the original problem will appear. Too far to the right and the drive will not take up the slack in the drive train in time to compensate for terrestrial rotation.

Altitude training may be performed in the normal fashion.

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Copyright ©1999-2000 Michael L. Weasner / etx@me.com
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