Furuno FAR-1416, Operator'S Manual

Page: 38 / 226

1. OPERATIONAL OVERVIEW
1-24
1.19 How to Reduce Sea Clutter
Echoes from waves cover the central part of the display with random signals known
as sea clutter. The higher the waves, and the higher the antenna above the water, the
further the clutter extends. When sea clutter masks the picture, reduce it with the A/C
SEA control, either manually or automatically.
Note 1: When both sea clutter and rain clutter are reduced, the sensitivity is de-
creased more than when only one is changed. For that reason adjust them carefully.
Note 2: The echo average (see "Echo Averaging" on page 1-28) 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.
1.19.1 How to select the method of clutter adjustment
1. Press the CURSOR ON/OFF key when cursor is not shown on the screen.
2. Move the cursor onto the [SEA AUTO] or [SEA MAN] (whichever is shown) at the
top of the display.
3. Press the left button to display [SEA (A)] or [SEA (M)] as appropriate.
1.19.2 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-029)
Rotate the AC/SEA knob ( F2 ). 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 paragraph 1.19.1.
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, rotate the
scrollwheel to increase/
decrease the A/C SEA. The setting range is [-50] to [50].
Place arrow inside window
to adjust A/C SEA.
A/C SEA adjustment method
(SEA AUTO or SEA MAN)
SEA MAN 70