microHAM ARCO Manual page 11

visible distant place which can be found on satellite maps. Find GPS coordinates of this distant
point https://www.gps-coordinates.net/, aim antenna to that place and enter coordinates to the
ARCO. Controller consequently compute heading value and register it as an calibration point.
Please note, if you are calibrating antenna heading to GPS coordinates, use GPS coordinates
for ROTATOR LOCATION first as QRA locator method is too coarse for accurate calibration.
SOLAR AZIMUTH. Since ARCO known your rotator location coordinates, time and date,
controller can compute exact sun position, and knows azimuth of the shadow projected by the
tower on the ground. To use it, you need to turn antenna in direction of the shadow. Precisely
align antenna boom shadow in parallel to the mast shadow and touch FORWARD button. Or
turn antenna to opposite direction, align antenna boom shadow in parallel to the mast shadow
and touch REVERSE button.
Once position is calibrated it is confirmed by CALIBRATION STATUS line showing
CALIBRATED message and ANT #1 AZIMUTH will display antenna azimuth.
ARCO allows to set software (SW) rotation limits. By default they are worked out from the
rotation center position and TOTAL ROTATION parameter from the Rotator tab. They can be
narrowed down by touching CW and CCW SW LIMITS buttons.
(Rotators with limit switches and POT and RHEO sensors)
If you have rotator with POT or RHEO absolute sensor, for a better accuracy near
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travel over these limits will damage sensor, hence is more safe to let ARCO sample
exact position of both limits.
Turn rotator to desired CW limit position but watch ROTATOR CENTER number to not
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exceed 99%. Touch CUSTOM button and enter antenna azimuth. On next window
confirm CW limit position.
Turn rotator to desired CCW limit position but watch ROTATOR CENTER number to not
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run under 1%. Touch CUSTOM button and enter antenna azimuth. On next window
confirm CCW limit position.
You can increase accuracy and improve heading linearity by adding more calibration
•
points. ARCO can register up to 72 calibration points if new point is more apart from the
old one than (Total Rotation / 72) degrees, what is 5º for rotators with 360º rotation
range. If new calibration point is within +/- 5º from old, ARCO will delete old, and use new
point instead. Position of calibration points are shown on calibration strip as small yellow
vertical lines.
If you want to reset all calibration data, touch RESET button and restart calibration.
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POST CALIBRATION INSTRUCTIONS
rotation ends we highly recommend to calibrate also CW and CCW limits,
even if they are already registered by AUTO button. Reason is that single
turn potentiometric sensors are typically used for its full travel but ends
are usually not linear. In addition, if such rotator has no hardware limits,
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