Sea Tel DAC-03, Инструкция по установке и эксплуатации

Страница: 27 / 80

DAC-03 Tracking Antenna Controller Basic System Information
3-3
Figure 3-2 Circular and Linear Polarization
3.2. Antenna Basics
The following information is provided to explain some of the basic functions of the antenna:
3.2.1. Azimuth
The CW / CCW rotation of the antenna is known as Azimuth. Azimuth drive, provided by the
azimuth motor, is required during stabilization, searching, tracking, and unwrap operations of the
antenna. When the boat turns, azimuth is driven in the opposite direction to remain pointed at the
satellite. The actual azimuth pointing angle to the satellite is determined by your latitude,
longitude, Heading and the longitude of the satellite. It is important to know that in normal
operation on a satellite, or when trying to acquire a satellite, the antenna should be pointed
generally toward the equator.
In the Northern Hemisphere, the azimuth angle to the satellite will be 180 degrees
true
(relative to
true north) if the satellite is at the same longitude that you are on. If the satellite is east, or west, of
your longitude the azimuth will be less than, or greater than 180 degrees respectively.
When checking for blockage you can visually look over the antenna radome toward the equator to
see if any objects are in line of site between the antenna and the satellite. If you are not able to
find any satellites it may also be useful to remove the radome top to see if the dish is aimed in the
correct direction (towards the equator).
3.2.2. Elevation
The antenna can be driven in elevation from 0 degrees (horizon) to 90 degrees (zenith). Elevation
drive, provided by the elevation motor, is required during stabilization, searching and tracking
operations of the antenna. The actual elevation pointing angle to the satellite is determined by
your latitude & longitude and the longitude of the satellite. In general, the elevation angle will be
low when you are at high latitudes and will increase as you get closer to the equator.
Refer to figure 3-1 above and note that from any given latitude, the elevation will be highest when
the satellite is at the same longitude that you are on. If the satellite is east, or west, of your
longitude the elevation angle will be lower.
3.2.3. Antenna polarization
If you have a circular polarization LNB installed, you do not need to adjust the “polarization” of the
antenna.
If you have a linear polarization
LNB installed, the system should
have been adjusted properly and
set-up in Auto-Polarization mode.
Auto-Polarization makes small
polarization adjustments
periodically as the boat changes
geographic locations by a
significant amount of latitude and
longitude. It also adjusts the
polarization of the feed when
changing from one satellite to
another.
Once polarization adjustment has
been optimized, it is NOT
necessary to readjust it as long as
the boat remains in the same
geographic area and stays on the
same satellite.