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 distinguish- able.

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 control until clutter has disappeared to lee- ward, but a little is still visible windward.

1.Confirm that the sensitivity is properly ad- justed, and then transmit on short range.

2.Adjust the [A/C SEA] control so small tar- gets are distinguishable but some clutter remains on the display.

Sea clutter at	A/C SEA control adjusted;
display center	sea clutter suppressed.

Figure 2-3 How to adjust the A/C SEA

control

Tip for adjusting the A/C SEA

Acommon mistake is to over-adjust the cir- cuit so all the clutter is removed. As an ex- ample set up for maximum A/C SEA. You will see how the center of the display becomes dark. This dark zone can be dangerous (tar- gets may be missed), especially if the sensi- tivity 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.

CAUTION

Turn off the A/C SEA control when its use is not required; the control can erase weak targets.

2.9Adjusting the A/C RAIN Control

(reducing rain clutter)

The vertical beamwidth of the scanner is de- signed to see surface targets even when the ship is rolling. However, by this design the scanner will also detect rain clutter (rain, snow, hail, etc.) in the same manner as nor- mal targets. Figure 2-4 shows the appear- ance of rain clutter on the display.

Adjusting A/C RAIN

When rain clutter masks echoes, adjust the [A/C RAIN] control. This control splits up these unwanted echoes into a speckled pat- tern, making recognition of solid targets easier.

Appearance of	A/C RAIN control adjusted;
rain clutter	rain clutter suppressed.

Figure 2-4 Effect of A/C RAIN

Note: In addition to reducing clutter, the [A/C RAIN] control can be used in fine weather to clarify the picture when navigating in confined waters. However, with the circuit activated the receiver is less sensitive. Therefore, turn off the circuit when its function is not required.

Automatic adjustments of A/C SEA and A/C RAIN

Push the [A/C AUTO] key. “A/C AUTO” ap- pears at the bottom left-hand corner of the display when the A/C AUTO circuit is on. You can fine tune by adjusting the [A/C SEA], [A/ C RAIN] and [GAIN] controls.

2-4