Sea Tel ST144-21, Installation And Operation Manual

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Maintenance and Troubleshooting ST144-21 C/Ku-Band TVRO
13-18
13.7.8.
The DacRemP Comm Diagnostics Window provides a means to enter in Remote Commands for driving
each individual torque motor to test that motors functionality. By driving each axis and observing the
resulting motion of the antenna, a coarse operational status of the motor and motor driver may be
established.
Open Loop Motor Test
•
To manually drive the motors, select the
“Comm Diagnostics”
window under to the Tools
submenu or Press “CTRL + C”
•
Using the small field in the upper left hand corner of
the window, type in the remote command and verify
the motor appropriately drives in the direction
commanded.
•
To drive the Cross Level motor, key in ^ 1064, ^ 1128 or
^ 1192 and press ENTER to drive the Cross Level axis
LEFT, OFF or RIGHT respectively.
•
To drive the Level motor, key in
^
2064,
^
2128 or
^
2192
and press ENTER to drive the level axis FORWARD,
OFF or BACKWARD respectively.
•
To drive the Azimuth motor, key in ^ 3064, ^ 3128 or
^
3192 and press
ENTER
to drive the azimuth axis CW,
OFF or CCW.
13.7.9.
Tracking optimizes the pointing of the antenna, in very fine step increments, to maximize the level of the
satellite signal being received. DishScan® is the default mode of tracking.
To Disable/Enable DishScan®
To toggle the ON/OFF state of DishScan®, select the remote parameter DISHSCAN. This remote parameter
allows you to view, or change, the DishScan® ON/OFF status.
1. Press UP arrow and ENTER to turn DishScan® ON.
2. Press DOWN arrow and ENTER to turn DishScan® OFF.
3. If you change this remote parameter, you must save the change using REMOTE PARAMETERS.
If DishScan® is OFF and the Step Integral parameter is set to 0000 , you will get a constant ERROR 0016
(DishScan® error) and you will see zeros flashing in the lower left of the Azimuth and Elevation ENTRY menu
displays. This is a visual indication that DishScan® is turned OFF.
When DishScan® is turned OFF, the system will NOT be able to properly track any satellite.
13.7.10.
The ships gyro compass input to the ACU may be accurate and stable in static conditions and yet may NOT
be accurate or stable enough in some underway dynamic conditions. If there is no gyro compass or if the
input is corrupt, not stable or not consistently accurate the tracking errors will become large enough to cause
the antenna to be mis-pointed off satellite.
Satellite Reference Mode
Satellite Reference Mode will uncouple the gyro reference from the azimuth rate sensor control loop. When
operating in Satellite Reference Mode changes in ships gyro reading will not directly affect the azimuth
control loop. The Pedestal Control Unit will stabilize the antenna based entirely on the azimuth rate sensor
loop and the tracking information from DishScan®. This will keep the azimuth rate sensor position from
eventually drifting away at a rate faster than the tracking loop can correct by using the tracking errors to
regulate the rate sensor bias.
Satellite Reference Mode can be used as a diagnostic mode to determine if tracking errors are caused by
faulty gyro inputs.
It should normally be
OFF as long as you have an accurate, reliable, gyro compass input available.
It MUST be
OFF
when the elevation angle is greater than 75 degrees. Above 75 degrees Elevation, the
ability of Sat Reference tracking to correct the Az Rate sensor bias begins to degrade, especially on a circular
C system.
Satellite Reference Mode
•
No Gyro Compass is available.
MUST be ON when:
•
The Gyro Compass input is noisy, occasionally inaccurate or occasionally unavailable.