Research Concepts RC2000A - Manual (Page 28)

28 RC2000A Dual Axis Antenna Controller Chapter 3 Installation
3.5 Slow Speed Adjustment
The Adapti-Drive slow speed control system allows the user to specify a desired slow speed. When the
antenna is moving at slow speed the controller will vary the voltage to the drive to maintain the actual
antenna slow speed at the value specified by the user. Other slow speed drive systems in use reduce
the voltage to the drive to a constant value whenever slow speed movements occur. This results in
poor speed regulation as the load on the motor varies or as friction in the drive system changes with
temperature.
For the RC2000A the user sets the slow speed for each axis independently by entering a slow speed
code via the AZIM SLOW and ELEV SLOW modes. This section outlines the procedure for selecting
the appropriate slow speed code. When the system memory is reset the azimuth and elevation slow
speed codes are initialized to 254. This code value effectively disables the slow speed system by
making slow speed equal to the maximum possible speed.
When slow speed movement occurs, the RC2000A determines the speed at which the actuator is
moving by measuring the rate at which position feedback pulses are received for the axis which is being
moved. The controller adjusts the voltage to the drive by using a Pulse Width Modulation (PWM)
scheme, which essentially turns the 36 volt drive voltage off and on very rapidly. Whenever the antenna
is manually jogged at slow speed (in MANUAL, SETUP, AZIM SLOW or ELEV SLOW modes) an
indication of the voltage delivered to the drive is displayed in the lower right hand corner of the display.
This quantity, referred to as a 'voltage code', varies from 1 to 24. The drive voltage associated with a
voltage code of 1 is the minimum voltage which can be delivered to the actuators. A voltage code of 24
is associated with the maximum voltage which can be delivered to the drive.
The azimuth slow speed is set in AZIM SLOW mode. In this mode the SCROLL UP and SCROLL
DOWN keys are used to change the speed code, the LEFT and RIGHT arrow keys can be used to jog
the antenna in azimuth at the selected slow speed, and the ENTER key is used to store the selected
speed code in non-volatile memory.
When jogging the antenna in the AZIM SLOW mode after the speed code has been changed through
the use of the SCROLL UP/DOWN keys, note that it may take 5-10 seconds for the speed to settle out
to a steady state value. Watch the voltage code displayed in the lower right hand corner of the display.
When the steady state condition is reached it should it should slowly toggle back and forth between a
pair of adjacent voltage codes.
After the voltage code settles to a steady state range of values, check the rate of movement to make
sure that it is slow enough to be useful but not so slow that the motor stalls or moves in a jerky fashion.
If the movement is not satisfactory, increase or decrease the speed code using the SCROLL UP and
SCROLL DOWN keys. Increasing the speed code will result in a faster slow speed. For most 36 volt
motors, an appropriate slow speed code will be in the range of from 140 to 175.
The elevation slow speed is set in ELEV SLOW mode. Note the values for the azimuth and elevation
slow speed codes may be set via the CONFIG mode Azim Slow Speed and Elev Slow Speed prompts.
Note that if the speed code for a given axis is set to 254 (the maximum speed code) the slow speed
system is disabled and full voltage is applied to the axis whenever slow speed is selected. If the speed
code is set to 254 and slow speed is selected, the SLOW banner and a voltage code will be displayed,
but the drive will move at fast speed and the voltage code will not change.
3.6 Programming Satellites
After the limits have been set and the slow speed code determined, satellites can be programmed into
the controller's memory. If the controller is used with an elevation over azimuth type of antenna mount,
the user should review this section along with the following section before programming in any
satellites. The following section discusses the display of azimuth and elevation position data in an
angle format and explains the use of the IBM PC programs found on the disk included with the
controller. Displaying the azimuth and elevation position in an angle format can be a great aid in
locating satellites.
All satellites are programmed into memory via SETUP mode. In SETUP mode the user can jog the
antenna in azimuth and elevation to peak up on a satellite, specify the satellite name and jog the
polarization to assign H and V polarization values. This information is retained in the controller's non-
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