System information

DAC-2202 Antenna Control Unit 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.