Sea Tel DAC-03, Инструкция по установке и эксплуатации

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Operation DAC-03 Tracking Antenna Controller
2-12
SEARCH DELAY
– default, or any number of seconds from 1-255 that you would prefer
that the ACU wait before starting an automatic search.
SWEEP INC
– default value (this parameter is not used in this search pattern).
GYRO TYPE – must NOT be set to zero.
SAT REF mode – may be ON if you are experiencing frequent, or constant, gyro read
errors (error code 0001). Must be ON if you are using NMEA Gyro input.
Target any satellite longitude value which includes even tenths digit values (ie SAT 101.0 W or SAT
101.2 W). If the desired satellite longitude includes an odd tenths digit, you must round it up, or
down, one tenth to make the tenths digit EVEN. The Antenna Control Unit calculates the Azimuth,
Elevation and Polarization values it will use to target the antenna. Initially the antenna will go to a
position that is 8 degrees above the calculated azimuth, until Azimuth, Elevation and Polarization
have had time to complete adjustment. Then the antenna will drive down to the calculated
elevation, which is the “Start” of the search pattern in the graphic below.
Then the antenna will search up in azimuth one Search Increment, search up one Search Increment
in elevation, search down two Search Increments in azimuth, search down two Search Increments
in elevation, etc until Search Limit is reached. When the end of the search pattern is reached, the
ACU will retarget the antenna to the start point shown in the graphic below.
If the desired signal is found at this position, or anywhere within the search pattern, the ACU will
terminate search and go into Tracking mode. If the desired signal is not found the ACU will wait
SEARCH DELAY seconds and then begin the search pattern again. This cycle will repeat until the
desired satellite signal is found or the operator intervenes.
2.7.2. Inclined Orbit Search Pattern
Some older satellites, in order to save fuel to keep them exactly positioned over the Equator, are in
an inclined geosynchronous orbit. The satellite remains geosynchronous but is no longer
geostationary. From a fixed observation point on Earth, it would appear to trace out a figure-eight
with lobes oriented north-southward once every twenty-four hours. The north-south excursions of
the satellite may be too far off the center point for a default box search pattern to find that satellite
at all times during the 24 hour period.
You can configure the ACU to do a special search pattern for a satellite that is in an inclined orbit by
using the following settings:
SEARCH INC - set to the default value for the frequency band that your antenna model is
currently being used for (typically 10 or 20 counts).
SEARCH LIMIT – leave this set to the default value for your antenna model.