Mid-Pass Handover; System With Only One Active Antenna - Orbit oceanTRX 4-500 Installation Manual

Antenna Handover

1.2.3 Mid-pass Handover

This type of handover is unexpected and occurs under one of the following conditions:
 Antenna to satellite communication path nears a (defined) blockage zone
 One of the operating antennas is faulty
1.2.3.1 Handover Due to Blockage Zones
A blockage analysis based on the antenna location and position is performed. As the path
of the transmitting antenna approaches within 30 minutes of the blockage zones,
blockage warnings are displayed at five minute intervals ("Blockage expected in
<30 min", "Blockage expected in <25 min", etc.). A short time before the anticipated
blockage, handover will be performed to the secondary antenna; if the secondary
antenna is within a blockage area as well, handover will be performed to the backup
antenna.
Both antennas continue to alternate for continuous coverage. In installations with three
antennas - if both antennas are expected to communicate over defined blockage zones,
handover will be made to the backup antenna.
The system takes into account some angular extension for the defined
Blockage Zones above the ship. This is used to cover for Blockage-
Zone measurement inaccuracies as well as the predicted Satellite path
deviations.
1.2.3.2 Handover Due to Faulty Antenna
If one of the active antennas is faulty, handover occurs to the other antenna. If both
antennas are faulty, handover will be performed to the backup antenna (if available).
A fault condition can also be incurred by one of the following:
 LAN communication problems between the ADE and BDE equipment
 Incompatible ADE or BDE software version
 IMU not locked
 Manual modifications of some of the critical operational settings of the antenna
 Lock indication from the modem not received – optional and can be changed by the
GUI

1.2.4 System with Only One Active Antenna

It is possible to use the system with only one active antenna, in this case:
 The antenna will not switch role when transferring to the next satellite – it will
continue transmitting.
 The new satellite selection happens exactly at handover time.
 The system periodically checks if there is another antenna that can be used.
1-6 OceanTRx™4-500 O3b System Installation Guide
Introduction