Suppressing Sea Clutter; Choosing Method Of Adjustment; Automatic Adjustment By The A/C Sea Control - Furuno FAR21x7 & BB FAR28x7 Operator's Manual BB FAR28x7 Operator's Manual

1. RADAR OPERATION
1.17

Suppressing 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 will extend. When sea clutter masks the picture,
suppress it by the A/C SEA control, either manually or automatically.
1.17.1

Choosing method of adjustment

1. Roll the trackball to choose SEA AUTO or SEA MAN (whichever is shown) at
the top of the display.
2. Push the left button to display SEA AUTO or SEA MAN as appropriate.
1.17.2

Automatic adjustment by the A/C SEA control

Auto A/C SEA allows for fine tuning of the A/C SEA circuit, within ±20 dB.
Accordingly, with the bar reading set to 100, 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 echoes because the STC curve is different depending size of echoes.
Note: The auto A/C function can erase weak target echoes. Adjust the control
carefully, watching the display.
By keyboard
1. Choose SEA AUTO following the procedure in paragraph 1.17.1.
2. While observing the A/C SEA level indicator, adjust the A/C SEA with the [A/C
SEA] control. 100 levels are available.
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SEA AUTO
A/C SEA adjustment
method (SEA AUTO or SEA MAN)
A/C SEA level indicator
Level bar
Place arrow inside window
to adjust A/C SEA.
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