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RC4000 ACU Boardset
3.2.2.3.4 Spiral Search Autopeak
The spiral search autopeak operation (SEARCH) performs somewhat differently from the SCAN
operation. Whereas SCAN counts on the fact that a non-inclined orbit satellite should be at the calculated
elevation, SEARCH must account for the fact that at a particular time an inclined orbit satellite may be
above or below the nominal target elevation. The figure shows the movements made to perform the
SEARCH operation.
1) as part of the basic LOCATE movement, the mount will be moved to the target elevation position and
the polarization axis will be moved to the correct orientation.
2) SEARCH will move to the target azimuth (correcting for elevation if needed) and take an initial signal
strength sample. Note that the target azimuth may be slightly off due to initial compass error.
3) If no hot spot is initially found, SEARCH will begin searching an area around the target position by
stepping in a CW/UP/CCW/DN sequence using increasing number of steps in each direction to effect
a spiral-like pattern. Unlike SCAN, SEARCH looks for a signal strength above a defined threshold in
order to declare an end to the SEARCH operation. Performing the total search pattern could be time
consuming so the search is terminated when a hot spot is found.
4)
If no satellite was detected, SEARCH moves back to the original target.
During the SEARCH operation, line 4 of the display shows the current direction and step number so the
user can keep track of the operation's progress.
AZIM:
ELEV: -61.7 (
POL:
SPIRAL SEARCH(CCW 12)
Note that when pulse-based position feedback is available, the automatic azimuth and elevation
movements are pulse rather than pot based for greater accuracy.
Chapter 3
0.0 (
-5.9)
SS1:523
44.8)
0.0 ( -45.0)
79
LOCATE
SAT:GALAXY 7
<STOP>HALT
Software
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