3-10 hsb
2
PLUS Series LCD Display
Adjusting Gain, Sea
Clutter, Rain Clutter
and Tune
Rain Clutter Control, using RAIN and FTC
Theradar can seeechoesfrom rain orsnow. Returnsfrom storm areasand rain
squalls consist of countless small echoes that continuously change size,
intensity, andposition.These returns,shown inFigure 3-8, sometimes appear
as large hazy areas, depending on the intensity of the rainfall or snow in the
storm cell.
The RAIN and FTC controls are used to reduce this clutter, so that targets
masked by the clutter can be seen on the radar picture.
•TheRAIN control is used to reduce large clutter masses around your vessel
caused by rain or snow.
•TheFTC (Fast Time Constant) control is used to reduce rain clutter at a dis-
tance from your vessel, such as that shown below.
Figure 3-8: Rain Clutter
When the FTC control is turned up, only the leading edgeof large (rain clutter)
echoes is displayed, while the effect on smaller (ship) echoes is only slight.
This means that you can also use the control on shorter ranges to distinguish
between two very close echoes on the same bearing, which may otherwise
merge and appear as one echo.
When the FTC control is turned up, the receiver is less sensitive, and there is a
reduction of background noise and fill-in returns from land and large targets.
You shouldtherefore turn the controldown when its useis not required. Since
storm cells are usually visible for long distances due to their extreme altitude,
you may wish to leave them displayed so that you can observe the location of
bad weather.
If you turn the RAIN or FTC control Off (equivalent to setting the level to 0%),
the actual setting is stored, and restored when you turn the control on again.
Note: RAIN and FTC are reset to Off at power-on.
RAIN
O
F
F
D3967-1
FTC
O
F
F
81186_3.book Page 10 Thursday, August 22, 2002 8:23 AM