RC4500 Antenna Controller Chapter 5 MODES – In Depth Descriptions
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5.1.2.5 Track
*** NOTE: The Track screen will only be available on RC4500 controllers that were purchased with the
inclined orbit tracking option. ***
The optional TRACK mode may be entered via the SETUP or RECALL modes if the selected satellite has
been described as having an inclined orbit.
Details of TRACK mode are available in the separate Appendix TRK describing inclined orbit tracking.
The following descriptions give an overview of how tracking is performed.
TRACKING INCLINED ORBIT SATELLITES. The RC4500 tracking algorithm can be divided into three
distinct stages - STEP_TRACK, MEMORY_TRACK, and SEARCH.
AZ: 31561 340.44 EXT:2730 TRACK
EL: 11060 49.27 SAT:BRASIL A1 (KU)
PL: 26517 6.54 STEP:PEAKING AGC
JOGGING ANTENNA TO FIND MAXIMUM SIGNAL
In STEP_TRACK, the controller periodically peaks on the receiver's signal strength by jogging the
antenna. The time and position are recorded in a track table maintained in the controller’s non-volatile
memory. The interval between peakups is determined by antenna beamwidth (determined from antenna
size and frequency band), satellite inclination and a user specified maximum allowable error (in dB).
When a track table entry exists for the current sidereal time, STEP_TRACK switches to
MEMORY_TRACK.
In MEMORY_TRACK, the controller smoothly moves the antenna to azimuth and elevation positions
derived from entries in the track table. The time between movements is determined by the same factors
which govern the time between peakup operations in STEP_TRACK. 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 receiver’s signal strength. If the
error exceeds a level set by the user, all entries in the track table are flagged for update.
TRACK_SEARCH is entered when the satellite signal has been lost. The RC4500 utilizes 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.
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