With ballistic tracking, the faster you increase or decrease the the throttle knob, the faster the data changes in the throttle.
When ballistic tracking is enabled, so are typematic keys. With typematic keys, when you press and hold the Y + or N - Keys, the values will continue to increase or decrease without having to do a separate key press for each increment.
DT402/DT400 are shipped with ballistic tracking enabled as the factory default setting.
Straight Line Tracking
With straight line tracking each movement of the throttle knob causes a fixed rate of change.
When you use straight line tracking, typematic key action is off. This means that you must press each key once to cause an action.