RC4500 Antenna Controller Chapter 4 Software Configuration / Installation
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4.2.4.3 Polarization Scale Factor
The polarization position sensor most often used is the potentiometer, although a resolver may also be
used. The scale factor for the potentiometer is given in degrees per volt, whereas the resolver scale
factor is given in pulses per radian. Before continuing, be sure to familiarize yourself with the type of
polarization position sensor that is used.
Note: in most cases the default scale factors for a mount will be correct and
should NOT be
changed. Perform scale factor calibration only if the Appendix B suggests that the scale factor for
your particular mount should be characterized.
4.2.4.3.1 Polarization Scale Factor for Potentiometer
VREF:2.500 OFF: 0.000 CONFIG-POL
CCW:-100.000 CW: 100.000 SF: 40.000
POT SCALE FACTOR <1.000-180.000 DEG/V>
To calculate the polarization scale factor, move the feed between two known physical polarization
positions and note the difference in the sensed polarization voltage between the two locations.
Example: at +90 degree reference position the polarization voltage is 3.86. At the -90 degree reference
position the polarization voltage is 1.14. The polarization scale factor is calculated as:
180 degrees / (3.86-1.14) = 66.16 degrees / volt
66.16 would be entered as the scale factor.
The polarization position sensor is the resolver and the scale factor is a constant that should not be
changed. The polarization scale factor can be found in the CONFIG – AZIMUTH CALIBRATION screen.
4.2.4.3.2 Polarization Scale Factor for Resolver
CONFIG-POL
CCW:-100.000 CW: 100.000
PSF:10431 ROFF: 0.000 DIR:0
RESOLVER OFFSET <+/-300.000 DEGREES>
PSF: PULSE SCALE FACTOR <1 – 32767 CNTS/RAD>
This value specifies the approximate number of pulses measured per radian of polarization travel. This
This value allows the ACU to correctly display the resolver position in angular format.
NOTE: The default value for this item will typically be correct.
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