Simrad GO XSE Series Operator's Manual page 115

Directional clutter rejection
This mode is active when Sea clutter is set to Auto or Harbor/
Offshore (options are dependent on the radar model). The gain of
the radar receiver is adjusted dynamically during the 360 deg.
sweep according to the sea clutter level, for increased target
sensitivity to leeward and in heavier sea states. For Halo radars it is
also possible to fine tune the directional clutter rejection with Auto
offset adjustments.
Ú Note:
This mode is not selectable in the menu and you cannot
see that it is activated in the panel or menu.
When Sea clutter is set to Manual, the Directional Clutter Rejection
mode will be OFF (non-directional).
Sea state settings of Calm, Moderate or Rough are available in the
menu to better optimize the radar image to your liking.
Gain
The gain controls the sensitivity of the radar receiver.
A higher gain makes the radar more sensitive to radar returns,
allowing it to display weaker targets. If the gain is set too high, the
image might be cluttered with background noise.
Gain has a manual and an automatic mode. You toggle between
automatic and manual mode in the slide bar.
Sea clutter
Filters the effect of random echo returns from waves or rough water
near the vessel.
When you increase the value, the sensitivity of the near field clutter
caused by waves is reduced. If the value is increased too much, both
sea clutter and targets will disappear from the display. Targets
around own ship may then not be shown as potentially dangerous
targets.
The system includes predefined sea clutter settings for harbor and
offshore conditions, in addition to the manual mode where you can
adjust the settings.
Ú Note:
At increasing levels of sea clutter, some targets cannot be
detected even by means of sea clutter filtering, since buoys or
other small objects are producing echoes of a level lower than
the ones coming from waves.
Radar | GO XSE/XSR Operator Manual
115