Step Track Hold Tracking
AvL Technologies
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4.1.3.
Step Track and Position Hold
In order to run StepTrack and Position Hold it needs to be set as the “Step Track Hold Operating Mode”. The
following configuration items control system behavior while in this mode.
“Step Track Hold Az Threshold”
“Step Track Hold El Threshold”
“Step Track Hold Gradient Threshold”
“Step Track Hold Noise Threshold”
“Step Track Hold Peaking Delay”
As mentioned before this mode is a combination of the two previous operating modes. Descriptions of these
configuration items can be found in section 4.1.1 and 4.1.2 of this document.
The Step Track and Postion Hold mode can be set up as an automatic continuation of the satellite acquisition process
via the “Run Track after Peak” or “Run Track after Acquire”. Once the mode has been activated, it will command
antenna movements whenever the antenna positioner has shifted from its original pedestal azimuth and/or
elevation position to a degree that exceeds user configurable thresholds or when the peaking delay has been
exceeded.
For the Step Track and Position Hold mode to be activated manually, it must be configured as the Step Track
Operating mode for the currently selected target. The module can then be activated by selecting the Track command
through the AAQ GUI (figure 5). It will remain active until another command is sent. The Track command on the AAQ
GUI will show as indicated whenever the module is in the position hold phase. When Step Track and Position Hold
mode has entered the fine peaking phase, the Peak command on the AAQ GUI will show as selected (figure 6).
When Step Track and Position Hold mode is activated it starts a timer which it checks against the “Step Track Hold
Peaking Delay” parameter. Once this delay interval has been reached, the antenna will enter the peaking phase and
perform fine peaking. Fine peaking (also accessible through the Repeak command) optimizes Rx signal strength by
optimizing antenna beam pointing. It does this by commanding small azimuth and elevation movements while
checking for peak Rx signal level. The original recorded pedestal values used by the position hold phase will then be
updated and overwritten with the new peaked coordinates determined by the Fine peaking process. Once the fine
peaking is complete, the timer is reset and the antenna returns to the position hold phase using the new coordinates
until the delay interval has been reached and the antenna reenters the peaking phase.
When Step Track and Position Hold mode completes the peaking phase, the module enters the position hold phase
and records current pedestal azimuth and elevation coordinates from the antenna positioner encoders or resolvers.
While the module remains in the position hold phase, it will command movements whenever the coordinates shift
from the recorded values by more than the user configurable thresholds to maintain a constant encoder or resolver
count. This mode further improves this backlash performance; the improved backlash performance will keep the
antenna beam pointed at a specific point even as external forces are applied to the antenna positioner/reflector. This
mode cannot compensate for sudden large movements (more than a few tenths of a degree) of the antenna base or
flexing of the antenna reflector.
