Furuno 1734C manual Reducing Sea Clutter, How the A/C SEA works, Gain sensitivity window

1.	Press the GAIN key to show the “gain adjustment”
	soft keys, and the last-used adjustment window	§GAIN SENSITIVITY
	appears. The example below shows the gain	AUTO ROUGH
	sensitivity adjustment window. The gain soft keys
		AUTO MODERATE
	shown depend on radar source as shown below.	°AUTO CALM
2.	If the gain sensitivity window is not displayed, press	MAN	0
	the GAIN soft key to show the gain sensitivity setting
	window.	Gain sensitivity 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.

2.5Reducing Sea Clutter

2.5.1How 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.

Sea clutter at	A/C SEA adjusted;
screen center	sea clutter suppressed

Effect of A/C SEA

2-3