Furuno FAR-2218, Operator'S Manual, Page: 54 / 294

1. OPERATIONAL OVERVIEW
1-32
2. Left-click to display [RAIN AUTO] or [RAIN MAN] as appropriate.
Note: Unlike sea clutter reduction, rain clutter cannot be finely adjusted when set
to [AUTO].
1.21.2 How to manually reduce the rain clutter
The vertical beam width 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.
Note: 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 great-
er the anti-clutter effect. When echoes from precipitation mask solid targets, adjust the
A/C RAIN control to split up these unwanted echoes into a speckled pattern, making
recognition of solid targets easier. Be careful remove all rain clutter, because you can
erase weak echoes. Further, the possibility of losing weak echoes is greater when you
use both A/C RAIN and A/C SEA to reduce clutter.
How to fine-tune rain clutter reduction from the control unit (RCU-014)
Rotate the A/C RAIN knob. Rotate anticlockwise to decrease the A/C RAIN, or clock-
wise to increase the A/C RAIN.
How to fine-tune rain clutter reduction from the on-screen box
1. Select [RAIN MAN], following the procedure in section 1.21.1.
2. Place the cursor on the level indicator inside the A/C SEA box at the top of the
display.
3. While observing the A/C RAIN level indicator, spin the scrollwheel to increase or
decrease the level. 100 levels (0-100) are available.
Note: The detection range is reduced when the RAIN is used to show targets in rain.
Generally, the amount of rain, TX pulse length and TX frequency are factors in deter-
mining how the detection range is affected. The figure below illustrates this.
Rain clutter at
screen center A/C RAIN control adjusted;
rain clutter reduced
40 RAIN MAN
Place the cursor inside the
level indication, then spin the
scrollwheel.