Suppressing Rain Clutter; Turning Auto Rain On Or Off; Adjusting A/C Rain - Furuno FCR-2107 Series Operator's Manual

2. Radar Operation
2.9

Suppressing Rain Clutter

Use the AUTO RAIN and A/C RAIN to suppress rain clutter. AUTO RAIN suppresses rain clutter in the picture and
A/C RAIN suppresses clutter picked up by the antenna.
When both sea clutter and rain clutter are reduced the sensitivity is decreased more than when only one is adjusted.
For that reason adjust them carefully.
The echo average is useful for reducing reflections from the sea surface. However, high-speed targets are harder to
detect than stationary ones when the echo average is active.
Be careful not to 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.
2.9.1

Turning AUTO RAIN on or off

1. Use the trackball to select the AUTO RAIN indication at the left side of the screen.
2. Push the left button to select the auto rain level desired. The indication changes in the sequence of OFF, 1, 2, 3
and 4. The higher the value the greater the suppression.
AUTO RAIN
2.9.2

Adjusting A/C RAIN

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.
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 A/C RAIN control to
split up these unwanted echoes into a speckled pattern, making
recognition of solid targets easier.
From the control unit w/keyboard
Adjust the A/C RAIN with the A/C RAIN control.
By trackball
1. Use the trackball to place the cursor on the A/C RAIN level indicator at the top right side of the display.
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Rain MAN
A/C RAIN level indicator
2. While observing the radar image, spin the scrollwheel downward to increase the A/C RAIN or upward to
decrease it. 100 levels (0-100) are available.
2-14
A/C RAIN level
Put arrow inside box
to adjust A/C RAIN.