Lacerta M-GEN User Manual page 43

When enabled they invert the apropriate axis' autoguider signal direction. It is
important to know that these inversions are made just before putting them physically
to the output and so they will invert all the signals generated by any part of the unit. If
a calibration data is used, these need to be disabled. Inverting one of them may be
necessary after a meridian-change of the mount (pointing to the same point of the sky
but physically differently).
At manual autoguiding setup (when the Camera's horizontal (X) axis is parallel to the
RA of the mount) this can be used to set the polarity of the image. For example using a
mirror will need one axis to be inverted.
• Manual: (button)
By pressing it the autoguider signals stop and the direction buttons can be used to
control them manually. On the screen a "MANUAL, ESC to quit" inverted text
indicates this manual control mode. You can exit this mode with pressing ESC.
May be used for checking the axes' directions or for maunal guiding for some
purpose.
• Calibration: (submenu)
Enters the Calibration screen to show and start or delete the current calibration data.
5.1.9.2.1 Calibration screen
The screen displays all of the current calibration data if there is one.
(The "Calibration" inverted text on the top indicates this screen.) If there
is no calibration data present, "no data" text is shown (see screenshot at
right) and only one option is possible: starting a new calibration with the
Calibrate
button.
The calibration procedure is the following:
First the DEC axis is moved according to the settings given in "guider settings" screen
(AG speed DEC value). (This helps the calibration to move the desired amount without a
knowledge.) If the star moved a little (no backlash is on the DEC now) the measurement of
the DEC direction and correction speed is started. After it the RA axis' direction and speed
can be measured now easier, the device supposes that the actual RA speed is equal or less
than the DEC's. (Less due to the actual DEC coordinate where the mount points to.)
After all is finished, both the directions and speeds are stored as the calibration data. The
correction speeds precision can't be checked diretly but the directions can. In an ideal case
these directions (vectors) are orthogonal to eachother but during the measurement the star
may drift some due to polar alignment failure or due to the periodic error of the RA axis. (The
constant speed drifts are mostly corrected by the measurement method.)
After the calibration the orthogonlity measure is displayed on the screen as "ortho.", in
percent. The interpretation of the resulting value is described later.
The calibration procedure can be interrupted by pressing ESC. The mount will stay in the
position where it was stopped. The mount is tries to set back to its original position only after
all the calibration steps has run.
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