The peak positions found by the step track may jitter due to noise. Specially, if an almost stable positioned satellite is tracked with a relatively small antenna, this jitter may be more than the real movement of the satellite. To stabilize the tracking in such situations, the sat-nms ACU provides a smoothing function which lets you reduce the pointing jitter.
The smoothing function is based in the fact, that most satellites (specially that ones which are on a stable orbit position) require the antenna to follow a small amplitude sine function with 24 hours cycle time in order to track the satellite optimally.
If you activate smoothing by setting the smoothing time to a non zero value, all peak positions of the last n hours get averaged by a sine function which matches the measured peaks at the best. After each step track cycle the antenna gets moved to the 'smoothed' position rather than to the recently evaluated peak position.
The usage of the smoothing function is recommended when tracking satellites where the antenna pointing oscillates less than 25% of the antenna's 3dB beamwidth. For tracking inclined orbit satellites, the usage of smoothing may be problematic as such satellites may require an significant position oscillation at 12 hours cycle time (sin 2wt). The smoothing function uses a simple sinusoidal model which does not provide this double frequency component. Hence, applying the smoothing function for such a satellite with more than 3 hours smoothing time may average the antenna movement path too much.