RESEARCH CONCEPTS RC4500 - Determine Offset Angles & Reference Voltages; Elevation Offset Angle

RC4500 Antenna Controller Chapter 4 Software Configuration / Installation
65
4.2.3 Determine Offset Angles & Reference Voltages
This section is used to determine the offset angles of the position sensor (typically a resolver or
potentiometer) for each axis. A proper offset angle will allow the displayed angle to match the antenna’s
true position.
Before continuing, an initial check of the resolver positions must be performed. Move the antenna over its
full range of travel on all axes and verify that the resolver wrap-around (step from 360° to 0°) does not
occur within the range of motion. If this does occur, loosen the retaining clamp of the offending resolver
and rotate it until the transition is out of the field of view. Be sure to re-tighten the clamp when finished.
The following procedures require pointing the antenna to known physical angles. One method to do this is
to use an Antenna Pointing Solution Calculator, such as RCI’s freeware: Antenna.exe (DOS) or
iWinAntennaCalculator Applets.exe (Windows). This software calculates the pointing angles of an
antenna to a satellite from a specific location on the earth (the antenna’s location.) The antenna can then
be manually jogged to point to the same satellite that was previously used for the calculation and then
peaked up. After the manual peak-up, the calculated angles from the program may be used as the
“known physical angle” that is requested in the following procedures.
4.2.3.1 Elevation Offset Angle
Step 1) Enter the MAINTENANCE – RES OFF screen.
RES TRUE REF RES OFF
a:179.87 359.87 0.00 ( 0.00)
e:181.14 181.14 0.00 ( 0.00)
<1-AZ,3-EL>REF <5>LON <7-AZ,9-EL>OFFSET
Step 2) Manually jog the elevation axis to a known physical angle (with respect to the local horizontal.)
Step 3) First verify that the “raw” resolver angle (under “RES”) is in approximately the center of travel.
Set the EL REF (Elevation Reference) to the same value as determined in Step 2.
RES TRUE REF RES OFF
a:179.87 359.87 0.00 ( 0.00)
e:181.14 181.14 22.30 ( 0.00)
<1-AZ,3-EL>REF <5>LON <7-AZ,9-EL>OFFSET
Now suppose that at this reference elevation position it is known that the true elevation RF look angle
should be 22.30 degrees. This angle will be entered in the elevation REF field after pressing 3.
Step 4) Calculate Resolver Offset
Press the <9> key on the keypad to calculate the new Resolver Offset angle.
RES TRUE REF RES OFF
a:179.87 359.87 0.00 ( 0.00)
e:181.14 22.30 22.30 (-158.84)
<1-AZ,3-EL>REF <5>LON <7-AZ,9-EL>OFFSET
The resulting display shows a displayed angle of 22.30.
Calculation: (181.14 – 158.84 = 22.30).
The Resolver Offset value will be automatically changed in the CONFIG – ELEVATION CALIBRATION
screen.