3.14.1.2 sat-nms ACU Indoor Unit & Outdoor Module Configuration

The diagram below shows the architecture of a antenna control system entirely built of sat-nms components. The 'sat-nms ACU Outdoor Module' controls the antenna pointing and performs the steptrack and adaptive tracking modes. The 'sat-nms LBRX Beacon Receiver' measures the satellite beacon level and supplies this level value on the Ethernet vie UDP Packets to the ODM. Both devices are controlled by the IDU through an Ethernet network (strictly spoken, the ODM also communicates with the beacon receiver directly, but this is for synchronization purposes only).

The indoor unit provides a comfortable graphical user interface which permits to monitor and control the whole antenna system. Beside this, it contains the so called 'Pointing Robot' , a software module which controls the antenna pointing according to the data evaluated from satellite ephemeris data sets or read from tables. This versatile tool superseeds the PROGRAM-Track function built into the ODM, which is not used in this configuration.

Configuring the antenna control system in this way is the favored solution. It achieves the best tracking results. More benefits are:

• The components of the antenna control system are optimally coordinated.
• Doing the step track locally in the ODM allows a very close timing of the operations during a steptrack cycle, this makes the tracking less susceptible to atmospheric variations of the beacon level.
• The tracking is completely independent from the indoor unit. If the IDU fails, the ODM still tracks the satellite.