Furuno FR-7112, FR-7252 Adjusting the A/C Rain Control Reducing rain clutter, Adjusting A/C Rain

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 hid- den 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 leeward, 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 re- mains on the display.

2.10Adjusting the A/C RAIN Control

(reducing rain clutter)

The vertical beamwidth of the antenna is de- signed to see surface targets even when the ship is rolling. However, by this design the unit will also detect rain clutter (rain, snow, hail, etc.) in the same manner as normal targets. Figure 2-5 shows the appearance of rain clutter on the dis- play.

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 pattern, mak- ing recognition of solid targets easier.

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

Figure 2-4 How to adjust the A/C SEA control

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 A/C SEA. 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 prop- erly adjusted. Always leave a little clutter vis- ible 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.

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

Figure 2-5 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 navi gating 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 SEA (A/C AUTO)] control. “A/ C AUTO” appears at the bottom left-hand cor- ner 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.

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