The sat-nms antenna control system -- regardless of the configuration used -- provides the basic types of satellite tracking:
Step Track
In plain step track mode, the ACU performs small test steps with the antenna in regular intervals to see if the receive level becomes better or worse for another antenna position. With the knowledge of the antenna pattern's shape, the tracking engine computes an optimized position from measurements taken at the old position and at the new one. Many parameters such as the step size, averaging times and the overall repetition interval are configurable by the operator.
Adaptive Track
The adaptive tracking mode works much like the plain step track, however the tracking engine in background computes a mathematical model of the antenna motions from the step track results. A great advantage of this mode is that the antenna follows the computed model even if the beacon reception fails. With the plain step track mode, the antenna would freeze in this case until the satellite beacon appears again.
Program Track
With the third tracking mode called program track, the antenna follows a position computed from the satellite's ephemeris data. The tracking engine accepts Keplerian elements in NASA 2-line format or the proprietary Intelsat ephemeris data format for this. For this tracking mode, no beacon reception is required, however the ephemeris data sets must be updated every few days.