ST88-21 C/Ku-Band TVRO
Maintenance and Troubleshooting
13-13
Cross-Level sensor is used to drive Cross-Level of the equipment frame to bring it to level (this
results in the tilt of the Cross-Level Beam being level).
Step 2. Azimuth axis activates - Antenna drives CW in azimuth until the “Home Flag” signal is
produced. This signal is produced by a Proximity sensor in close proximity to a metal tab. After a
short period of time (a total of approximately 1-2 Minutes after power is initially applied to the
antenna), the PCU will report its model setting and software version number to the Antenna Control
Unit (ACU).
This completes the phases of initialization. At this time the antenna elevation should 45.0 degrees and
Relative azimuth should be at home flag (home switch actuated).
If any of these steps fail, or the ACU reports model "
xx97B or xxx00B
", re-configure the PCU as described
in the Maintenance section of this manual. If initialization still fails, this indicates a drive or sensor problem.
13.7.4.
Antenna Loop Error Monitoring
The DacRemP
DISPIVC
graph chart provides a means for monitoring the accumulated velocity errors of the
antenna for diagnostic purposes. If this error is excessive, it indicates external forces are acting on the
antenna. These forces may be the result of but not restricted to static imbalance, excessive bearing friction,
cable binding, or wind loading. If these forces cause the antenna to mis-point by more than 0.5° from the
desired position the PCU will flag a “Stab Limit” error.
•
To view the position error, select the
graph chart.
•
This chart displays sensed axis errors via three traces, CL (Cross Level), LV (Elevation), and AZ
(Azimuth), at a fixed 0.05
º
/ vertical division.
•
The normal trace average will plots its display
±
3 divisions from the red reference line. Any trace
line average plotted above this is of concern and troubleshooting required. The example below
shows the forces exerted onto the antenna as a resultant of DishScan® Drive. The example below
shows the results of various forces put upon antenna.
Содержание ST88-21 C/Ku-Band TVRO
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