Research Concepts RC2000A - Manual (Page 30)

30 RC2000A Dual Axis Antenna Controller Chapter 3 Installation
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 which 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. To run the antenna.exe program, simply type ANTENNA followed by the
enter key at the 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 scale2.exe program to calculate the AZIMUTH
SCALE, AZIMUTH OFFSET, ELEVATION SCALE, and ELEVATION OFFSET parameters which
will be entered into the controller via CONFIG mode.
4. With the controller, go to CONFIG mode and enter in the values for those parameters determined in
step 3. At the CONFIG mode Angle Display Enable item, enter 1 to enable the angle display
feature. The antenna longitude and latitude values must also be specified via CONFIG mode. 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.
For mounts which 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 arc to perform the
calibration with.
3.8 AutoPol
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. The
AutoPol feature, when enabled, is active whenever the controller is in MANUAL and REMOTE modes.
Note that the H, V, and SKEW keys do not work when AutoPol is enabled. The AutoPol input of the
RC2000A 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. It is not necessary to use the AutoPol feature with 2 port feeds that receive
horizontal and vertical polarizations simultaneously.
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
the AutoPol input. One side of the relay can be connected to ground and the other side connected to
the AutoPol input. When the relay is active the AutoPol input is connected to ground - a low level input,
and when the relay is open the AutoPol input floats high due to the pull-up in the RC2000A.
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