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2-3
1. Press the GAIN key to show the “gain adjustment”
soft keys, and the last-used adjustment window
appears. The example below shows the gain
sensitivity adjustment window. The gain soft keys
shown depend on radar source as shown below.
2. If the gain sensitivity window is not displayed, press
the GAIN soft key to show the gain sensitivity setting
window.
3. Use the Cursor pad to select AUTO ROUGH, AUTO
MODERATE, AUTO CALM, or MAN (manual) as
appropriate. Select an AUTO option according to the sea state.
4. For manual adjustment, rotate the ENTER knob to adjust, while observing the radar
echo. The range of adjustment is 0-100.
5. Press the GAIN key on the front panel or the RETURN soft key to finish.
Adjusting the FTC
To suppress rain clutter from heavy storms or scattered rain clutter, adjust the FTC.
In addition to reducing clutter, the FTC can be used in fine weather to clarify the picture
when navigating in confined waters. However, with the circuit active the receiver is less
sensitive.
1. Press the GAIN key.
2. Press the FTC soft key, and then rotate the ENTER knob toadjust.
3. Press the GAIN key on the front panel or RETURN soft key to finish.
2.5 Reducing Sea Clutter
2.5.1 How the A/C SEA works
Echoes from waves can be troublesome, covering 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. Sea clutter may affect radar performance
because real targets are sometimes hidden by the echoes of small waves. (See the
left-hand figure in the figure below.) When sea clutter masks the picture, adjust the A/C
SEA to reduce the clutter.
The A/C SEA reduces the amplification of echoes at short ranges (where clutter is the
greatest) and progressively increases amplification as the range increases, so amplification
will be normal at those ranges where there is no sea clutter.
A/C SEA adjusted;
sea clutter suppressed
Sea clutter at
screen center
Effect of A/C SEA
GAIN SENSITIVITY
AUTO ROUGH
AUTO MODERATE
AUTO CALM
MAN
0
Gain sensitivity window