RESEARCH CONCEPTS RC4500 - Azimuth Offset Angle; Azimuth Offset Angle - Northern Hemisphere

RC4500 Antenna Controller Chapter 4 Software Configuration / Installation
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4.2.3.2 Azimuth Offset Angle
The goal of this step is to approximately align the azimuth axis’ displayed true heading angle to True
South (if antenna is in Northern hemisphere) or True North (if in Southern hemisphere). True South or
True North will be referred to as the azimuth reference position. As with the initial elevation calibration, a
more precise azimuth calibration will be done later with respect to a known satellite.
NOTE: there are 3 angles discussed with respect to azimuth angle. They are defined here to try to avoid
confusion:
1) Resolver Angle – actual angle read from the resolver sensor. This angle will read from 0.00 to 359.99.
It is important that throughout the antenna’s full range of azimuth movement the resolver does not “wrap
around” (i.e. move from 0.0 to 359.99 or from 359.99 to 0.00). The recommended way to achieve this
situation is to rig the resolver close to its center of travel (180.00 deg.) when the antenna is approximately
at its reference position (either True North or South).
2) True Heading Angle – this is the azimuth angle (TRUE) most commonly displayed for the RC4500.
This represents the true (not magnetic) heading that the antenna is pointing. For fixed-based applications
this is the most common angle used when referring to the antenna’s azimuth position.
3) Antenna Angle – internally within the RC4500, the “antenna” angle (AZIM) is calculated as a value
between -180.00 and 180.00 with 0.00 typically being around the center of travel of the axis. This version
of azimuth angle is more commonly used throughout the RC4000 mobile antenna controller applications
that the RC4500 was derived from.
Follow these steps if the antenna is located in the northern hemisphere.
4.2.3.2.1 Azimuth Offset Angle – Northern Hemisphere
Step 1) Enter the MAINTENANCE – RES OFF screen.
RES TRUE REF RES OFF
a:179.05 0.00 0.00 (-359.05)
e:181.14 22.30 22.30 (-158.84)
<1-AZ,3-EL>REF <5>LON <7-AZ,9-EL>OFFSET
Step 2) Manually jog the antenna to approximately True South.
Step 3) First verify that the “raw” resolver angle (under “RES”) is approximately its center of travel
(resolver angle (RES) ≈ 180.00 deg).
Set the AZ REF (Azimuth Reference) to the same value as determined in Step 2.
RES TRUE REF RES OFF
a:179.05 0.00 180.00 (-359.05)
e:181.14 22.30 22.30 (-158.84)
<1-AZ,3-EL>REF <5>LON <7-AZ,9-EL>OFFSET
Now suppose that at this reference azimuth position, REF is changed to 180.00 for True South. This
angle will be entered in the azimuth REF field after pressing the <1> key on the keypad.
Step 4) Calculate Resolver Offset
Press the <7> key on the keypad to calculate the new Resolver Offset angle.