System information

Maintenance and Troubleshooting 9497B-20 Ku-Band TVRO
7-4
Receiver and each of the Ku-Band Satellite Receivers is connected by coax cable to one of the
available IF outputs of the Matrix Switch. Total signal loss of this path is the accumulation of the
coax cable losses from antenna to receiver, plus the loss in the Matrix Switch.
7.3.3. Antenna Initialization (Series 97B & Series 00 )
Turn the pedestal power supply ON. The PCU will initialize the stabilized portion of the mass to be level with
the horizon and at a prescribed Azimuth and Elevation angles. The antenna will go through the specific
sequence of steps (listed below) to initialize the level cage, elevation, cross-level and azimuth to
predetermined starting positions.
Initialization is completed in the following phases, each phase must complete properly for the antenna to
operate properly (post-initialization). Observe the Initialization of the antenna pedestal.
Step 1. The brakes on the Elevation and Cross-Level motors release.
Step 2. The level platform motor drives the Level Cage CW, issuing extra steps to assure that the
cage is all the way to the mechanical stop. Then the Level Cage will be driven exactly 45.0 degrees
CCW.
Step 3. 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 4. 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 5. 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 "xx97", 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.
7.3.4. Troubleshooting using DacRemP
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.
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) Targeting
Sea Trial ADMC (Position) Targeting
Tracking
Stabilization