Furuno FAR-2218, Operator'S Manual, Page: 52 / 294

1. OPERATIONAL OVERVIEW
1-30
1.20.2 How to fine-tune sea clutter reduction
Auto A/C SEA allows for fine tuning of the A/C SEA circuit, within ±20 dB. Accordingly,
with the bar reading set to 50, gain is not lowered to minimum as with manual A/C SEA
on close-in ranges. Further, the auto A/C SEA level is low because the average value
of the original input echo is low in areas where there are no sea surface reflections.
For example, when the ship is alongside a quay and the radar picture shows echoes
from both land and sea, you can observe the size of the echoes because the STC
curve changes with the size of the echoes.
Note: The auto A/C function can erase weak target echoes. Adjust the control care-
fully, watching the display.
How to fine-tune sea clutter reduction from the control unit (RCU-014)
Rotate the AC/SEA knob. Rotate anticlockwise to decrease the AC/SEA, or clockwise
to increase the A/C SEA.
How to fine-tune sea clutter reduction from the on-screen box
1. Select [SEA AUTO], following the procedure in section 1.20.1.
2. Place the arrow on level indicator inside the A/C SEA box at the top of the display.
3. While observing the A/C SEA level indicator, spin the scrollwheel to adjust the
clutter reduction. The setting range is [-50] to [50].
1.20.3 How to manually reduce sea clutter
Note: The proper setting of the A/C SEA should be 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. Be careful not to remove
all sea clutter, because you may erase weak echoes. Further, the possibility of losing
weak echoes is greater when you use both A/C SEA and A/C RAIN to reduce clutter.
How to reduce sea clutter manually from the control unit (RCU-014)
Rotate the AC/SEA knob. Rotate anticlockwise to decrease the AC/SEA, or clockwise
to increase the A/C SEA.
20 SEA AUTO
Place the cursor inside the
level indication, then spin the
scrollwheel.
Sea clutter at
screen center
A/C SEA control adjusted;
sea clutter reduced