Furuno FAR-21 7-BB Series, Operator'S Manual

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1. RADAR OPERATION
1-27
By trackball
1. Choose SEA AUTO following the procedure in paragraph 1.17.1.
2. Roll the trackball to place the arrow in the A/C SEA level indicator at the top
of the display.
3. While observing the A/C SEA level indicator, roll the wheel downward to
increase the A/C SEA or upward to decrease it. 100 levels (0-100) are
available.
1.17.3 Manual adjustment of A/C SEA
The A/C SEA control 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.
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 setting is set too
low, targets will be hidden in the clutter, while if the setting is 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.
A/C SEA adjusted;
sea clutter suppressed
Sea clutter at
screen center
By keyboard
1. Choose SEA MAN following the procedure in paragraph 1.17.1.
2. Watching the A/C SEA level indicator at the top of the display, adjust the A/C
SEA with the [A/C SEA] control. 100 levels (0-100) are available.
By trackball
1. Choose SEA MAN following the procedure in paragraph 1.17.1.
2. Roll the trackball to place the arrow on the A/C SEA level indicator at the top
of the display.
3. While observing the A/C SEA level indicator, roll the wheel downward to
increase the A/C SEA or upward to decrease it. 100 levels (0-100) are
available.