Furuno FCR-2107 series, Operator'S Manual

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2. Radar Operation
2-13
2.8.1 Automatic adjustment by the A/C SEA control
Auto A/C SEA allows for fine tuning of the A/C SEA circuit, within ±20 dB. Accordingly, with the bar reading set
to 100, gain is not lowered to minimum as with manual A/C SEA on close-in ranges. Further, the auto A/C SEA
level is low because the average value of the original input echo is low in areas where there are no sea surface
reflections. For example, when the ship is alongside a quay and the radar picture shows echoes from both land and
sea, you can observe the size of echoes because the STC curve is different depending size of echoes.
Note: The auto A/C function can erase weak target echoes. Adjust the control carefully, watching the display.
1. Use the trackball to select SEA MAN (whichever is shown) at the top of the display.
2. Push the left button to display Sea AUTO.
A/C SEA level
Put arrow inside box
to adjust A/C SEA.
61
Sea AUTO
From the control unit w/keyboard
While observing the radar image, adjust the sea clutter with the A/C SEA control. 100 levels are available.
By trackball
1. Use the trackball to place the arrow in the A/C SEA level indicator at the top of the display.
2. While observing the radar image, spin the scrollwheel downward to increase the A/C SEA or upward to
decrease it. 100 levels (0-100) are available.
2.8.2 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.
Be careful not to remove all sea clutter, because you may erase weak echoes. Further, the possibility of losing weak
echoes is greater when you use both A/C SEA and A/C RAIN to reduce clutter.
From the control unit w/keyboard
1. Use the trackball to place the arrow in the Sea AUTO box.
2. Push the left button to show Sea MAN.
3. Watching the radar image, adjust the A/C SEA with the A/C SEA control. 100 levels (0-100) are available.
By trackball
1. Use the trackball to place the arrow in the Sea AUTO box.
2. Push the left button to show Sea MAN.
3.
Put the cursor on the A/C SEA level indicator.
4. While observing the radar image, spin the scrollwheel downward to increase the A/C SEA or upward to
decrease it. 100 levels (0-100) are available.