position shall be moved in the PROGRAM, I11 and TLE tracking modes.
Polarization prediction --- Actually not implemented.
Target orbit position --- The nominal orbit position of the satellite (??E). This value is used
for the initial pointing of the antenna if the 'initial pointing mode' is set to 'ORBIT'.
Inclination --- Actually not implemented.
Pointing Angles
Az target value /El target value / Pol target value / Pol2 target value --- The pointing
angles stored with the target are used to position the antenna if the initial pointing mode is
set to 'STORED-POSITION'.
Steptrack Parameters
Tracking step size --- The tracking step size is a very important parameter for the
performance of the tracking. It defines the size of every depointing step, the ACU makes in
order to find out where the optimal antenna pointing is. Setting too high values will cause
significant signal degradations during the step track cycle because the antenna moves a too
large amount away from the satellite. Setting the value too small will let the beacon level jitter
mask the level differences caused by the test steps, the antenna will not track the satellite
properly.The step size is specified as a percentage of the antenna's half 3dB beamwidth.
The ACU calculates the beamwidth from the antenna diameter and the beacon frequency.
Expressing the step size in this relative way keeps the value in the same range, regardless
of the type of antenna. The recommended value for this parameter is 15-20%. You may want
to start with 20% and try to reduce down to 15% if the signal degradation during tracking
becomes too high.The tracking step size is a common parameter for both axes. If both axes
behave differently, you can tweak the antenna diameter settings in the setup. Specifying a
larger diameter makes the ACU using a smaller step size for this axis.If the tracking step
seems to be completely out of range, you should check if the beacon frequency is set
properly. The frequency must be the true receive frequency at the antenna, entered in MHz,
not an L-band frequency or other IF.
Beacon frequency --- This parameter tells the ACU the frequency of the beacon signal to
be used for tracking. The ACU calculates the antenna beam width from this frequency and
the antenna diameter configured at the setup page. The value has to be entered as true
receive frequency, no L-band or other IF frequency. When used with a SatService beacon
receiver, the ACU automatically reads the beacon frequency at the start of each tracking
cycle from the receiver. Any value entered here will be overwritten in this case. The beacon
frequency entered here never sets the frequency at the receiver, neither with a SatService
receiver nor with a third party device!
Level offset --- Principally there are two ways to display a beacon receive level: Either as
an absolute level in dBm as reported by the receiver or as a relative level with '0dB'
signalling the nominal level at clear sky conditions. The latter gives an easy measure for any
degradation of the receive level.The parameter 'Level offset' lets you calibrate the absolute
reading of the beacon receiver to the relative level. You may either enter a value to shift the
reading by this offset or you may glick to the 'calc.' link beside this parameter to set the
offset to the actual absolure level reading, makting the actual level being 0dB relative.
Level threshold --- If the beacon level falls below this threshold value, the ACU does not
perform a step track cycle. If the level falls below the threshold during the steptrack cycle,
the cycle gets aborted.If the ADAPTIVE tracking is enabled and there is enough data in the
tracking memory, the ACU computes a mathematical model from the stored data and predicts
the antenna pointing position from the extrapolation of the model. Analoguously the antenna
is moved to the actual TLE it I11 position in such a case if the 'STEP-TLE' or 'STEP-I11'
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