Sea Tel DAC-03, Инструкция по установке и эксплуатации

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DAC-03 Tracking Antenna Controller Basic System Information
3-1
3. Basic System Information
This section provides you with some additional information about the satellites you will be using, some basics of
your satellite antenna system and other equipment within your system configuration. For more information about
you specific antenna, refer to its manual.
3.1. Satellite Basics
The satellites are in orbit at an altitude of 22,754 miles (36,619 kilometers) and are positioned directly
above the equator. Their orbital velocity matches the Earth’s rotational speed, therefore, each appears to
remain at a fixed position in the sky (as viewed from your location).
Your antenna can be used with any of the satellites in this orbit that have a strong enough receive signal
level. Your antenna is capable of being fitted with a Linear or Circular feed assembly. This feed assembly
may be designed to operate at, but not limited to, C-Band frequencies, Ku-Band frequencies or be capable
of operation in both bands. With the correct feed assembly you will be able to receive the linear or circular
signal at the specific frequency range of the desired satellite.
3.1.1. C-Band Receive Frequency (3.7-4.2GHz)
At these frequencies the signal from the satellite travels only in a straight line and is affected by
weather changes in the atmosphere. There are several conditions that can cause a temporary loss
of satellite signal, even within an area where the signal level is known to be adequate. The most
common of these
normal temporary losses are blockage and rain fade . They will interrupt
services only as long as the cause of the loss persists.
3.1.2. Ku-Band Receive Frequency (10.95-12.75GHz)
At these frequencies the signal from the satellite travels only in a straight line and is affected by
weather changes in the atmosphere. There are several conditions that can cause a temporary loss
of satellite signal, even within an area where the signal level is known to be adequate. The most
common of these
normal temporary losses are blockage and rain fade . They will interrupt
services only as long as the cause of the loss persists.
3.1.3. Blockage
Blockage is loss due to an object in the path of the signal from the satellite to the reflector. If an
object that is large and dense and is positioned in the path of the signal from the satellite, it will
prevent sufficient signal from arriving at the dish. Satellite signals can not bend around, or
penetrate through, these objects and the reception will be degraded or completely interrupted. The
reflector is actively driven to remain pointed at the satellite (which is generally pointed towards the
equator) so, as the ship turns a mast or raised structure of your ship may become positioned
between the satellite and the dish. Blockage may also be caused by anything located between the
radome and the satellite, which may include but not limited to, tall mountains, buildings, bridges,
cranes or other larger ships near your ship. Moving or rotating the ship to position the antenna
where it has an unobstructed view to the desired satellite will restore the antennas’ ability to receive
the satellite signal.
3.1.4. Rain Fade
Atmospheric conditions that may cause sufficient loss of signal level include rain, snow, heavy fog
and some solar activities (sun spot and flare activity). The most common of these is referred to as
“rain fade”. Rain drops in the atmosphere reduce the signal from the satellite. The heavier the rain
the higher the amount of signal loss. When the amount of loss is high enough, the antenna will not
be able to stay locked onto the satellite signal. When the amount of rain has decreased sufficiently,
the antenna will re-acquire the satellite signal. In a strong signal area, at Ku-Band rain fall of about