Research Concepts RC2000C - Manual (Page 68)

60 RC2000C Az/El Tracking Antenna Controller Chapter 5 Modes Function Description
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5. Since a stronger signal was measured when the antenna moved up, the controller concludes that
the satellite has moved up. The controller will record the signal strength at the current antenna
position, and again move up by one position count. At the new position, the controller will measure
the signal strength again to determine if the signal is stronger at the new position than at the starting
position. This process will continue until a weaker signal strength is recorded. When that occurs,
the controller will back up one step and conclude that it has found the elevation peak.
6. A problem occurs if the controller makes the wrong decision at step 4. Any time the controller step
size is comparable in magnitude to the antenna's mechanical hysteresis, a problem WILL eventually
occur.
For most antennas the Max Track Error should not be made smaller than 5 (0.5 dB).
SEARCH ENABLE
SEARCH ENABLE:1 CONFIG
0-DISABLE, 1-ENABLE ENT,BKSP,SCRLL ^v
The Search Enable CONFIG mode item specifies whether or not the Intelli-Search algorithm is enabled
or disabled. When the STEP TRACK submode is active and the signal strength input indicates that the
satellite transponder has gone down, the controller will switch to the SEARCH sub-mode. The Search
Enable CONFIG mode item is the controlling item for the Search Width CONFIG mode item which is
described next.
If the Search Enable CONFIG mode item is enabled, the controller will execute the Intelli-Search
algorithm. During an Intelli-Search, the controller will perform a serpentine-shaped search over a region
where the controller has calculated that the satellite's apparent motion will take it. If the satellite is not
found during the Intelli-Search, the search is periodically repeated until either signal strength information
is available, or track table information becomes available.
If the Search Enable item is disabled, the user is simply prompted to manually position the antenna on
the satellite and hit the ENTER key to continue. The Intelli-Search should be disabled for transmit
applications. It may also be advantageous to disable Intelli-Search for antennas that move very slowly.
SEARCH WIDTH
SEARCH WIDTH:3 CONFIG
1-10, NOMINAL=3 ENT,BKSP,SCRLL ^v
The Search Width item controls the width of the sweeps that occur during execution of the Intelli-Search
algorithm. If the angular extent of the sweeps is too large, the controller could mistakenly align the
antenna with an adjacent satellite. A search with narrow sweeps takes much less time to complete, but
may not sweep over a region which is wide enough to find the satellite.
The Search Width is not an absolute value - increasing its value results in wider sweeps, and
decreasing its value narrows the sweeps. The actual pointing angle over which search sweeps occur is
a function of the antenna beamwidth and the Search Width parameter. For a given Search Width value,
the search sweeps of an antenna with a narrower beamwidth will be greater than for an antenna with a
larger beamwidth.
The default Search Width value of 3 is appropriate for satellites with 2-degree spacing. For faster
searches, the value can be lowered to 1 or 2.
Access to the Search Width CONFIG mode item is only allowed when the Search Enable CONFIG
mode item described above is set to 1 (enabled).
5.10.12 Expert Access Flag
Expert Access is used to control access to CONFIG mode items. When the Expert Access flag is set
(ON), the user has access to all controller modes and all CONFIG mode items. When the Expert
Access Flag is reset (OFF), the user is locked out of several modes and most CONFIG mode items.