76 GPSMAP
®
4000/5000 Series Owner’s Manual
Radar
Default Gain and Clutter Settings
Setting Default Value Instructions
Gain Auto See “Automatically Adjusting Gain on the Radar Screen” (page 76)�
Sea Clutter Calm See “Restoring the Default Sea Clutter Setting” (page 77)�
Rain Clutter Off See “Restoring the Default Rain Clutter Setting” (page 78)�
FTC Off See “Restoring the Default FTC Setting” (page 78)�
Crosstalk On See Adjusting Crosstalk Clutter on the Radar Screen” (page 80)�
Automatically Adjusting Gain on the Radar Screen
is the default value for the gain setting. The automatic gain setting for each radar mode is optimized for
that mode, and may differ from the automatic gain setting used for another mode.
: Depending upon the radar in use, the gain setting congured for use in one radar mode may or may
not be applied to other radar modes or to the Radar Overlay (page 75).
1. From the Home screen, select .
2. Select , , , , or mode.
3. Complete an action:
• Select > > for Cruising, Harbor, Offshore, or Sentry mode.
• Congure the setting for the short-range screen in Dual Range mode. Select > > >
for the GPSMAP 4000 series. Select > > for the GPSMAP 5000 series.
• Congure the setting for the long-range screen in Dual Range mode. Select > > >
for the GPSMAP 4000 series. Select > > for the GPSMAP 5000 series.
The chartplotter sets the gain automatically once based on average conditions, the range of the radar
signal, and the selected radar mode. The chartplotter does not readjust the gain automatically in response to
changing conditions.
Manually Adjusting Gain on the Radar Screen
For optimal radar performance that accounts for actual conditions, you can manually adjust the gain.
: Depending upon the radar in use, the gain setting congured for use in one radar mode may or may
not be applied to other radar modes or to the Radar Overlay (page 75).
1. From the Home screen, select .
2. Select , , , or mode.
3. Complete an action:
• Select > for Cruising, Harbor, Offshore, or Sentry mode.
• Congure the setting for the short-range screen in Dual Range mode. Select > > for
the GPSMAP 4000 series. Select > for the GPSMAP 5000 series.
• Congure the setting for the long-range screen in Dual Range mode. Select > > for
the GPSMAP 4000 series. Select > for the GPSMAP 5000 series.
4. Select to raise the gain, until light speckles appear across the Radar screen.
Data on the Radar screen is refreshed every few seconds. As a result, the effects of manually adjusting the
gain may not appear instantly. Adjust the gain slowly.
5. Select to lower the gain until the speckles disappear.
6. If boats, land, or other targets are within range, select to lower the gain until the targets begin to
blink.
7. Select to raise the gain until the boats, land, or other targets appear steadily lit on the Radar screen.
8. If necessary, minimize the appearance of nearby large objects (page 76).
9. If necessary, minimize the appearance of side-lobe echoes (page 77).
Minimizing Nearby Large-object Interference
Nearby targets of signicant size, such as jetty walls, can cause a very bright image of the target to appear on
the Radar screen. This image can obscure smaller targets located near it.
: Depending upon the radar in use, the gain setting congured for use in one radar mode may or may
not be applied to other radar modes or to the Radar Overlay (page 75).
