How To Suppress Rain Clutter; How To Reduce Rain Clutter Automatically; How To Reduce Rain Clutter Manually - Furuno FCR-2119-BB Operation Manual

2.6

How to Suppress 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.
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 rec-
ognition of solid targets easier.
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.
Note 1: 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.
Note 2: The echo average feature 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.
2.6.1

How to reduce rain clutter automatically

Control Unit: Push the A/C RAIN control to display [AUTO1], [AUTO2], [AUTO3] or
[AUTO4] on RAIN mode indication on the Status bar. The higher the number the great-
er the degree of rain clutter reduction.
RAIN mode indication
Trackball module: Click the [RAIN] mode indication on the Status bar to display [AU-
TO1], [AUTO2], [AUTO3] or [AUTO4]. The higher the number the greater the degree
of rain clutter reduction.
2.6.2

How to reduce rain clutter manually

Control Unit: Push the A/C RAIN control to display [MAN] on the [RAIN] mode indi-
cation on the Status bar. While watching the radar picture, adjust the A/C RAIN control
to reduce the clutter.
Trackball module: Click the [RAIN] mode indication on the Status bar to show [MAN].
For coarse adjustment, put the cursor within the slider bar area then push the left but-
ton. For fine adjustment, put the cursor at the end of the slider bar then roll the trackball
while pushing and holding down the left button. Release the button to finish.
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 figures on the next page illustrate this
occurrence.
2. RADAR, CHART RADAR OPERATION
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