Setting Azimuth And Elevation Limits; Motor Drive Polarity; Elevation Movement - Inclined Orbit Operation - RESEARCH CONCEPTS RC2000C Manual

RC2000C Polar Tracking Antenna Controller
the rotating feed, polarization motor, or potentiometer may occur if the limits are exceeded. If the user
attempts to jog the polarization motor and no movement is detected on the position sense lines, or
movement is detected in the wrong direction, the ANTENNA POL alarm will activate. If a polarization
alarm is active, an error message will flash on the bottom row of the display, and the polarization drive will
be disabled. The alarm can be de-activated via RESET mode.
4. Once the polarity of the motor drive and sense lines have been verified, the pol limits may be set. To
set the limits, the pol motor is jogged to each position where it is desired to set a limit. This is done
from MANUAL mode (with the Rotating Feed CW Limit and CCW Limit CONFIG mode items set as
described above). It is recommended that an assistant be stationed at the antenna to ensure that the
polarization motor's (or sensor's) mechanical limits are not exceeded. Record the count shown on
the display at each of these positions for CW and CCW limit. Return to CONFIG mode, and enter
these new limits for Rotating Feed CW Limit (the lower value) and Rotating Feed CCW limit (the
greater value).
3.4

Setting Azimuth and Elevation Limits

The next step in the installation procedure is to ensure that the polarity of the motor drive wiring is correct,
the position sensors and polarotor function properly, and then to set the azimuth and elevation limits. If
there is an optional 24V pol drive installed, the polarotor function does not need to be checked. If the
polarotor does not function properly (or if there is no polarization control of any type in the system), make
sure that the Rotating Feed Present CONFIG mode item is set to 0.
All of the operations outlined in this section can be carried out with the controller in LIMITS mode. IN
LIMITS MODE THE USER HAS UNRESTRICTED MOVEMENT OF THE ANTENNA, THERE ARE NO
SOFTWARE AZIMUTH OR ELEVATION LIMITS, AND ANTENNA JAMMED SENSING DOES NOT
TAKE PLACE. WHEN MOVING THE ANTENNA IN LIMITS MODE AN ASSISTANT SHOULD BE
STATIONED AT THE ANTENNA TO INSURE THAT THE ANTENNA DOES NOT MOVE PAST A
PHYSICAL LIMIT. NOTE ALSO THAT THE CW AND CCW POLARIZATION ADJUSTMENT KEYS
ARE ACTIVE.
3.4.1

Motor Drive Polarity

The polarity of the azimuth motor drive is checked by depressing the LEFT ARROW key and verifyingthat
the antenna moves east. If the antenna does not move in the proper direction , connector J2 pins 4and 6
need to be reversed. The polarity of the elevation motor drive is checked in a similar fashion. TheUP
ARROW key corresponds to up elevation movement.
The azimuth and elevation position sensor operation can be checked by jogging the antenna about the
appropriate axis and verifying that the position count changes for that axis. Note that the position count
will always decrease for east and down movement, and will always increase for west and up movement.
Also the count will not decrement lower than 1 or increment higher than 65535.
Polarotor operation is checked by using the CW and CCW keys to skew the polarization.
3.4.2

Elevation Movement - Inclined Orbit Operation

This section guides the installer through the process of insuring that the range of antenna elevation
movement is adequate to track the desired inclined orbit satellites. The tracking algorithms employed by
the RC2000C assume that the mount has been configured so that when the elevation position is equal to
the value specified by the Geo Elevation Position, the antenna can be aligned with the geostationary
satellite with movement only about the azimuth axis. This is the manner in which a single axis polar
mount is adjusted to 'track the arc'.
The apparent motion of an inclined orbit satellite is a narrow figure eight pattern. The inclination of the
orbital plane of satellites in an inclined orbit can typically be as great as 10 degrees ( referenced to the
center of the earth). As seen from the surface of the earth, the angular extent of the apparent motion of
the satellite will be approximately plus and minus 1.2 times the Clarke Belt. The long axis of the figure
eight is oriented perpendicular to the Clarke Belt at the position along Clarke Belt where the satellite
would reside if it were geostationary. The center of the figure eight lies on the Clarke Belt and the motion
of the satellite is symmetrical about the Clarke Belt. The installer must configure the mount such that the
range of elevation movement of the antenna is symmetrical about the Clarke Belt.
Research Concepts, Inc. • 5420 Martindale Road • Shawnee, Kansas 66218-9680 • USA
Chapter 3 Installation/Setup 15
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