Autopol - RESEARCH CONCEPTS RC2000C Manual

RC2000C Az/El Tracking Antenna Controller
The following step by step procedure can be used to locate geo-stationary satellites. In the process, the
parameters needed to display azimuth and elevation parameters in an angle format will also be
determined.
1. Determine the antenna latitude and longitude. Obtain a satellite guide and identify the pair of
satellites that will be located initially and used to calibrate the angle display. A reasonable selection
would be a pair of satellites with many readily identifiable active transponders that are located 10 to
15 degrees apart (in longitude) placed somewhere in the middle of the arc.
2. Invoke the antenna.exe program to determine the magnetic heading and elevation angle needed to
intercept each satellite. If the elevation angles calculated for the two satellites are within 4 degrees,
select another satellite. To run the antenna.exe program, simply type ANTENNA followed by the
enter key at the DOS prompt. Position the antenna on each satellite. A magnetic compass and an
inclinometer can be used to help point the antenna in the proper direction. For each satellite, record
the longitude and the antenna azimuth and elevation count values where the satellite was located.
3. After the two satellites have been found, invoke the scale3.exe program on the floppy disk in the
back of this manual to calculate the Display Az Gain, Display Az Offset, Display El Gain, and
Display El Offset parameters which will be entered into the controller via CONFIG mode.
4. In this step the values obtained in step 3 are entered into the controller's memory via CONFIG
mode. Activate CONFIG mode, and enable Expert Access (section 2.5). At the Angle Display
Enable CONFIG mode item, enter a 1 to enable angle display. Next, enter the values obtained in
step 3 for Display Az Gain, Display Az Offset, Display El Gain, and Display El Offset. Values must
also be entered for the Antenna Latitude and Antenna Longitude CONFIG mode items. A latitude
or longitude entry is performed in two parts. The numerical value is entered first (followed by the
ENTER key). Next the direction is specified, either E (East) or W (West) for longitude or N (North)
or S (South) for latitude (followed by the ENTER key).
Be sure to terminate all CONFIG mode numeric entries with the ENTER key. When all of the
parameters have been entered, scroll back through the list to make sure that each entry is correct.
5. To locate additional satellites, invoke the antenna.exe program to determine the true heading and
the elevation angle required to intercept the satellite. Note that when the controller's angle display
feature is enabled, the azimuth position is displayed as a true heading. Simply jog the controller
until the displayed azimuth position matches the true heading value predicted by the antenna.exe
program and the displayed elevation position matches the elevation value predicted by the program.
Jog the antenna in azimuth about the predicted position to find the satellite
For mounts that employ linear actuators, there will be an error in the controller's displayed values for
true heading and elevation. The error will be negligible when the antenna is located near the satellites
used to calibrate the angle display (the satellites found in step 2). The error will be greater as the
antenna is moved away from those satellites. This occurs because the controller uses a linear mapping
of position counts to display angle. For a mount which uses a linear actuator, the actuator forms one
side of a triangle and as that side gets shorter or longer, the opposite angle changes. For this case the
mapping of position counts to antenna pointing angle is described by trigonometry and will be non-
linear. To minimize the error, try to choose a pair of satellites in the middle of the arc to perform the
calibration.
This section covers the installation and software configuration required to use the AutoPol feature. The
AutoPol function allows the antenna polarization to be controlled via a digital input to the controller.
When enabled, AutoPol is active whenever the controller is in MANUAL or TRACK mode. Note that the
H, V, POL CW and POL CCW keys do not work when AutoPol is enabled. The AutoPol input of the
RC2000C is driven by a digital output from a satellite receiver. The AutoPol input responds to a digital
level, with a high level being one polarity and a low level the other polarity. The mapping of a high level
on the digital input to either H or V polarization is referred to as the AutoPol polarity, and is controlled
via a CONFIG mode item.
The AutoPol input on the controller has an internal pull-up resistor which means that the input will float
high when it is not driven by the receiver. This allows the receiver to use a relay contact closure to drive
Research Concepts, Inc. • 9501 Dice Lane • Lenexa, Kansas • 66215 • USA
Chapter 3
3.8

AutoPol

Installation/Setup
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