Research Concepts RC2000A - Manual (Page 27)

RC2000A Dual Axis Antenna Controller Chapter 3 Installation/Setup 27
defined as seen by an observer located above the antenna looking down on the antenna. If the
antenna does not move in the proper direction, connector J2 pins 4 and 6 need to be reversed. The
polarity of the elevation motor drive is checked in a similar fashion. The UP 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 azimuth counter-clockwise and down movement, and will always increase for
azimuth clockwise and up movement. Also the count will not decrement lower than 1 or increment
higher than 65535.
Polarotor operation is checked by using the POL CW and POL CCW keys to skew the polarization.
3.4.2 Setting Limits
The azimuth counter-clockwise and/or down limits are set first. The bottom row of the display prompts
the user to set the limits for each axis. To set a limit, position the antenna at the desired limit, and hit
either the 7 key to set an azimuth limit or the 9 key to set an elevation limit. When the counter-
clockwise azimuth limit or down elevation limit is set, the position count for the axis is reset to 30. The
limits should be specified so that there is adequate clearance between the antenna and any obstacles
when the antenna is positioned at any azimuth/elevation combination within the limits.
3.4.3 Geo Elev Position
After the upper antenna limit has been set the installer is prompted to 'SET GEO LIMIT'. This refers to
the Geo Elevation Position. This quantity should be specified for modified polar antenna mounts. For
az/el mounts this quantity has no meaning and the user can exit LIMITS mode by depressing the MODE
key. It is not necessary to set the Geo Elevation Position at this time because this quantity can be
specified via CONFIG mode at any time.
A properly adjusted polar mount can track the geostationary satellites with movement of the antenna
about the polar axis. A modified polar mount is a polar mount whose elevation angle (sometimes also
referred to as latitude angle) adjustment has been motorized. The Geo Elevation Position is the
elevation position where it is possible to nominally track the geostationary satellites with movement
about the polar axis.
When system memory is cleared, the Geo Elevation Position is reset to zero. Whenever the Geo
Elevation Position is zero the elevation position which is displayed will be the actual elevation position
count, the down limit is 30 and the up limit will be some value greater than 30. Once the Geo Elevation
Position has been set, all elevation position values are displayed relative to the Geo Elevation Position.
When the antenna is located at the Geo Elevation Position (assuming it has been set), the displayed
elevation position will be 0.
A simple example will illustrate the interaction between the Geo Elevation Position and the elevation
display. The user enters LIMITS mode and sets the CCW limit. After the down limit is set the displayed
elevation position is 30. The user then moves the antenna to a position of 175 and sets the upper limit.
At this point the displayed elevation position is 175. The user then moves the antenna to an elevation
position of 100 and sets the Geo Elevation Position. The displayed elevation position is then 0. After
the Geo Elevation Position has been set, when the antenna is at the down elevation limit the displayed
elevation position is -70 (30 - 100), and when the antenna is at the up elevation limit the displayed value
will be 75 (175 - 100).
When LIMITS mode is entered, if a non-zero Geo Elevation Position exists, it is temporarily reset to
zero so that the actual elevation position count is displayed. If the user resets the down and up
elevation limits without resetting the Geo Elevation Position, the Geo Elevation Position is permanently
reset to zero when LIMITS mode is exited. If the user exits LIMITS mode without changing the down
and up elevation limits, the Geo Elevation Position which existed on entry is restored.
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