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Procedure, Field Replacement, Level Cage Kit, Base Exit
1.
Brief Summary:
Troubleshooting document for diagnosing a fault with and replacing the level cage assembly.
2.
Checklist:
Verify Remote Tilt
Verify Initialization
Verify Sensor Outputs using DacRemP
Azimuth and Relative Targeting
Drift and Sensor Monitoring
3.
Theory of Operation:
The level cage contains 4 sensors. These are a fluid filled tilt sensor which is used as the systems horizon reference (level
position) and long term stabilization reference, and 3 solid state rate sensors, one for each axis which acts as the
antennas short term stabilization reference. A faulty sensor inside the level cage will cause the antenna to lose stability
and mispoint from the satellite under dynamic conditions although the system may appear to be operational in the port
when there is no motion to counteract. This document will run through testing the sensors inside the level cage,
replacing the level cage assembly and calibrating the systems remote tilt setting.
4.
Verify Remote Tilt:
If the pedestal is having stability problems firstly check the remote tilt setting by looking at the level bubble on top of the
level cage (note: older systems didn't have a bubble installed on top of the level cage). If the bubble isn't as close to
central as possible the remote tilt setting isn't correctly calibrated, meaning the rate sensors won't be correctly aligned
with their axis. This will cause the rate sensors to output incorrect feedback into the PCUs control loop, potentially
causing a stabilization issue. Calibrate the remote tilt setting as per the instructions at the end of this document and
continue to test the level cage using the follow procedures.
5.
Verify Initialization:
Power cycle the pedestal
1.
Brakes release (if applicable)
2. Level cage drives to its end stop, then backs off exactly 45 degrees
3.
Elevation axis drives to 45 degrees based on the level cages horizon reference
4. Cross level axis drives to level based on the level cages horizon reference
5.
Unlimited azimuth systems drive clockwise until the home flag and sensor make contact
6. Limited azimuth systems drive clockwise into the azimuth end stop, then back off to 630 degrees of
relative
If any of these steps fail, or the ACU reports model "xx03/xx04", the antennas N0 parameter needs calibrating and
verified it saves correctly. A drive issue or pedestal error requires further troubleshooting.
Page 1 of 9
Copyright © Sea Tel, Inc 2011 - The information contained in this document is proprietary to Sea
Tel, Inc.. This document may not be reproduced or distributed in any form without prior written
consent of Sea Tel, Inc.
Document No
135266 Rev B
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