Onwa Marine Electronics KR-1338C v.1 - Manual (Page 25)

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-
Rol 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
Sea clutter at
display center A/C SEA control adjusted;
sea clutter suppressed.
Tip for adjusting the A/C SEA
A common mistake is to over-adjust the circuit so all the clutter is removed. As
an example set up for maximum STC. You will see how the center of the display
becomes dark. This dark zone can be dangerous (targets may be missed),
especially if the sensitivity is not properly adjusted. Always leave a little clutter
visible on the display to be sure weak echoes will not be suppressed. If there is
no clutter visible on the display, turn off the circuit.
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