Sea Tel 9497B-21 Скачать руководство пользователя страница 55

Страница: 55 / 104

9497B-21 C/Ku-Band TVRO

Maintenance and Troubleshooting

7-13

Step 2.  Elevation axis then activates - Input from the LV axis of the tilt sensor is used to drive the
Elevation of the equipment frame to bring the tilt sensor LV axis to level.  This step takes
approximately 10 seconds and will result in the dish being at 45.0 degrees in elevation. The level
cage may still be tilted left or right at this time.
Step 3.  Cross-Level axis activates - Input from the CL axis of the tilt sensor is used to drive Cross-
Level of the equipment frame to bring the cross-level axis of the tilt sensor to level (this results in
the tilt of the Cross-Level Beam being level).  This step takes approximately 10 seconds.
Step 4. Azimuth axis activates -  Antenna drives CW in azimuth until the “Home Flag” signal is
produced. This signal is produced by a Home Switch hitting a cam (or by a Hall Effect sensor in close
proximity to a Magnet). After another 10 second wait, the antenna will report its version number at
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 engaged on the home flag cam).
If any of these steps fail, or the ACU reports model "

97", re-configure the PCU as described in the this

chapter. If initialization still fails, this indicates a drive or sensor problem, refer to the Troubleshooting
section.

7.7.4.

While troubleshooting a Sea Tel 3-Axis Antenna System, you must classify the fault you are dealing with as a
failure within one of 3 major system functions, Targeting, Stabilization, and Tracking. Should there be a
failure with any one of these functions, your system will not operate properly. A few simple checks may help
determine which fault (if any) that you are dealing with. The matrix below lists some test(s) and which of the
DacRemP graph selection would be best to use to identify a fault. The end of this chapter contains examples
on how to use DacRemP to diagnose a fault.

Troubleshooting using DacRemP

Targeting:   is the ability to accurately point the antenna to an angular position in free space and is
controlled by the ACU.  (Does the system drive to the Azimuth, Elevation, and Polarity positions within 1
degree of the desired satellite?)
Stabilization:  is the process of de-coupling the ships motion from the antenna and is controlled by the
PCU. (Does the system maintain the satellite link after turning off TRACKING?)
Tracking:

is the process of issuing fine adjustments to the

pointing

angle of the antenna to optimize the

received signal level and is controlled by the ACU. (Does the system pass a four quadrant-tracking test?)

Functional Test(s)

DacRemP Graph
Selection to use

System Function(s)

Four Quadrant Tracking.

ADMC (Position)

Tracking

Azimuth Encoder Verification.

ADMC (Position)