Onwa Marine Electronics KR-12X8 - Manual (Page 23)

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 scanner above the water, the further the clutter will extend. Sea clutter appears
on the display as many small echoes which might affect radar performance. (See
the Figure 2-4.) When sea clutter masks the picture, adjust the A/C SEA control to
The [A/C SEA] control reduces the amplification of echoes at short ranges (where
clutter is the greatest) and progressively increases amplification will be normal at
2.13 Adjusting the A/C SEA Control (reducing sea clutter)
How the A/C SEA control works
reduce the clutter.
those ranges where there is no sea clutter.
Adjusting the A/C SEA control
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 control is set
Too low, targets will be hidden in the clutter, while if it is set too high, both sea
clutter and targets will disappear from the display. In most cases adjust the con-
trol until clutter has disappeared to leeward, but a little is still visible windward.
1. Confirm that the sensitivity is properly adjusted, and then transmit on short
range.
2. Adjust the [A/C SEA] control so small targets are distinguishable but some
clutter remains on the display.
Figure 2-4 How to adjust the STC control
A/C SEA control adjusted;
sea clutter suppressed. Sea clutter at
display center
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