Furuno FR-8122 EU - Manual (Page 25)

1. OPERATIONAL OVERVIEW
1-14
1.11.3 Manual sea clutter adjustment
1. Push the A/C SEA control to show “SEA MAN” as the A/C SEA adjustment method.
2. Rotate the A/C SEA control to suppress sea clutter.
The proper setting of the A/C SEA control is such that the clutter is broken up into small dots, and
small targets become distinguishable. If the setting is set too low, targets will be hidden in the
clutter, while if the setting is too high, both sea clutter and targets will disappear from the display.
In most cases adjust the control until clutter has disappeared to leeward, but a little is still visible
windward.
Appearance of sea clutter
1.12 Suppressing Rain Clutter
The vertical beamwidth of the antenna is designed to see surface targets even when the ship is
rolling. However, by this design the unit will also detect rain clutter (rain, snow, or hail) in the same
manner as normal targets.
The A/C RAIN control adjusts the receiver sensitivity as the A/C SEA control does but rather in a
longer time period (longer range). The higher the setting the greater the anti-clutter effect. When
echoes from precipitation mask solid targets, adjust the control to split up these unwanted echoes
into a speckled pattern, making recognition of solid targets easier.
1.12.1 Choosing rain clutter adjustment method
Rain clutter may be adjusted automatically or manually. Push the A/C RAIN control to choose
automatic or manual adjustment alternately. The adjustment method currently chosen is show at
the top right corner of the screen. In the example below the rain clutter adjustment method is
“AUTO.”
A/C RAIN indicator
A/C SEA control adjusted;
sea clutter suppressed
Sea clutter at
screen center
A/C RAIN adjustment method (AUTO)
TUNE AUTO
GAIN AUTO
SEA AUTO
RAIN AUTO