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RayTech Navigator User’s Guide
5-16
Rain Clutter Control
The radar can see echoes from rain or snow. Returns from storm areas
and rain squalls consist of countless small echoes that continuously
change size, intensity, and position (Figure 5-6). These returns
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.
• The RAIN control is used to reduce large clutter masses around
your vessel caused by rain or snow.
• The FTC (Fast Time Constant) control is used to reduce rain
clutter at a distance from your vessel, such as that shown below.
Figure 5-6. Radar Rain Clutter Display
When the FTC control is turned up, only the leading edge of 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 should therefore turn the control down when its
use is 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.