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RC4600 ACU Board Set
2.1.1.2.2.3.6 Spiral Search
The Spiral Search operation performs somewhat differently from the Azimuth Scanning operation.
Whereas Azimuth Scanning counts on the fact that a non-inclined orbit satellite should be at the
calculated elevation, Spiral 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 Spiral 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) Spiral 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, Spiral 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 create a spiral-like pattern. Spiral Search looks for a signal strength above a defined
threshold to declare an end to the Spiral Search operation. If TLE information is available for the
satellite, the Spiral Search will perform a search that is wide in azimuth and short in elevation.
The term for this is a "Flat Spiral Search"
4) At the end of the Spiral Search, the RC4600 will perform a Peak Up (2.1.1.2.2.3.4) and a Box
Peak (2.1.1.2.2.3.5).
During the Spiral 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.
A Z :
E L :
S P I R A L S E A R C H ( C W 1 )
Chapter 1
- 1 . 8 1 7 (
- 2 . 0 )
4 4 . 8 6 8 (
4 4 . 8 )
39
B C N :
5 0
L O C A T E
S A T : O G 1
< S T O P > H A L T
Introduction
S I G
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