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RC4600 ACU Board Set
If the satellite selected is a Preset Satellite that has been previously tracked, the screen below will appear
before prompting the user to confirm that the antenna is peaked on target. The user should choose if a
new track is desired or if they would like to resume an existing track.
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Once the user has confirmed the antenna is currently peaked on the satellite, the controller will begin the
TRACK operation.
Details of TRACK mode are available in the separate appendices TRK and TLE describing inclined orbit
tracking. The following descriptions give an overview of how tracking is performed.
The RC4600 tracking algorithm can be divided into four distinct stages:
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Step Track
In Step Track, the controller periodically peaks on the selected signal source by jogging
o
the antenna in azimuth and elevation. The time and position are recorded in a track table
maintained in the controller's memory. The interval between Step Track operation is
determine from antenna size, frequency band, satellite inclination and a specified
maximum allowable error. When a track table entry exists for the current sidereal time,
Step Track can transition to Memory Track or TLE Track depending on the TRACK
MODE configuration.
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Memory Track
In Memory Track, the controller smoothly moves the antenna to azimuth and elevation
o
positions derived from entries in the track table. The time between movements is
determined by the same factors which govern the time between Step Track operations.
By increasing the maximum allowable error, antenna movements can be performed less
frequently. In Memory Track, the accuracy of the track table is monitored by periodically
peaking up on the selected signal source. If the error exceeds the maximum allowable
error, all entries in the track table are flagged for update.
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Two-Line Element (TLE) Track
In TLE track, the controller smoothly moves the antenna to azimuth and elevation
o
positions derived from the two-line element data set. The RC4600 will be constantly
calculating pointing angles from the TLE data set. Anytime the current position is
different from the calculated position, the RC4600 will move the antenna to close this
error.
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Track Search
Track Search is entered when the satellite signal has been lost. The RC4600 utilizes
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Intelli-Search, an efficient search algorithm that minimizes errors associated with
traditional box searches and frees the user from having to update vague search window
parameters. This scheme accounts for the specific mount geometry, calculates the
nominal trajectory for the satellite, and then searches in an area that coincides with the
satellite's expected path. When the satellite is located, the controller re-enters the Step
Track mode.
Chapter 1
T R A C K T A B L E D A T A A L R E A D Y E X I S T S
< M O D E > E X I T
41
Introduction
T R A C K
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