The problem comes about when you use semi-automatic mode.
Semi-automatic mode (also known as point and shoot) allows
you to use an arrow key to quickly select the heading you want
and then release the arrow key and the antenna rotates to
that heading. This way you don't have to hold down the
arrow key and watch the rotator move, and then release it
when you get to the heading you want. If the antenna is pointed
at 5 degrees and semi-automatic is used to select 355 degrees,
the antenna will rotate the long way around (right) moving a total of
350 degrees instead of moving left 10 degrees. It is true as
you indicate that you can change to manual mode and then use
the left arrow key to move the antenna directly to 355, assuming
overtravel is enabled. Similarly, automatic mode, which is used
with computer control, has the same problem.
I should also note that even if you have the antenna south centered,
the semi-automatic and automatic modes are programmed to avoid the
overtravel region. Thus the overtravel feature really only works
in manual mode. It is fairly clear IMHO that whoever wrote the
firmware for the controller had only a superficial understanding
> I'm not concerned about the DCU-1 protocol (yet) but the lack of
> North-centering does concern me. From reading the manual, quoted
> below, it seems that after doing the reset procedure, one can indeed
> go both sides of North, with the ccw direction being in "over-travel"
> mode but perfectly usable. Are you saying your rotator can not do
> Here is the quote from the manual:
> "Since there are no mechanical limits in the rotator, it may be
> installed with the antenna pointing in any direction. There is no
> reason to locate ?TRUE NORTH? until you are ready to calibrate the
> control box. Use the controller to position the antenna to physically
> point north, then reset the controller as follows:
> Turn the unit OFF.
> While holding the button depressed turn control unit back on. This
> will now show on the display. The controller is now set for
> North. The display may also show ? press the button to cycle
> thru to the normal (i.e. blank) setting.
> This feature can be used if, for any reason, the direction of the
> antenna becomes incorrect. This may be caused by antenna to mast
> slippage or incorrect initial alignment.
> The AlfaSpid rotator is now set at the counter-clockwise end of its
> normal rotation range. Normal rotation range is in a clockwise
> direction for 360 degrees.
> From the reset position, you can rotate counter-clockwise an
> additional 180 degrees in over-travel, as well 360 degrees clockwise,
> plus an additional 180 degrees into clockwise over-travel.
> Counter-clockwise over-travel is indicated by a steady dot above the
> over-travel icon. Rotation past 359 degrees into the clockwise
> over-travel is indicated by a blinking dot above the over-travel
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