Stopping The Transmission Of Radar Signals; Optimizing The Radar Display; Range Of Radar Signals; Radar Gain And Clutter - Garmin GPSMAP 800 series Owner's Manual

If the boat heading is based on data from a magnetic heading
sensor or an automatic pilot, the heading data could be
compromised due to incorrect setup, mechanical malfunction,
magnetic interference, or other factors. If the heading data is
compromised, the Radar overlay may not align perfectly with
the chart data.

Stopping the Transmission of Radar Signals

From a Radar screen, select MENU > Radar to Standby.
TIP: Press from any screen to quickly stop radar
transmission.

Optimizing the Radar Display

You can adjust the radar display settings for reduced clutter and
increased accuracy.
NOTE: You can optimize the radar display for each radar mode.
1
Select a radar range (Range of Radar
2 Restore the default value of the gain setting (
on the Radar Screen Automatically).
3
Adjust the gain setting manually (
Radar Screen Manually).

Range of Radar Signals

The range of the radar signal indicates the length of the pulsed
signal transmitted and received by the radar. As the range
increases, the radar transmits longer pulses in order to reach
distant targets. Closer targets, especially rain and waves, also
reflect the longer pulses, which can add noise to the Radar
screen. Viewing information about longer-range targets can also
decrease the amount of space available on the Radar screen
for viewing information about shorter-range targets.

Radar Gain and Clutter

Adjusting Gain on the Radar Screen Automatically

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.
NOTE: Depending upon the radar in use, the gain setting
configured for use in one radar mode may or may not be
applied to other radar modes or to the Radar overlay.
NOTE: Not all options and settings are available on all radar
and chartplotter models.
1
From a Radar screen or the Radar overlay, select MENU >
Gain.
2
Select an available option:
• Select Auto.
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 adjust
the gain automatically in response to changing conditions.
• Select Auto Harbor or Auto Offshore.
The chartplotter automatically adjusts the gain for the
conditions.

Adjusting Gain on the Radar Screen Manually

For optimal radar performance, you can manually adjust the
gain.
NOTE: Depending upon the radar in use, the gain setting
configured for use in one radar mode may or may not be
applied to other radar modes or to the Radar overlay.
1
From a Radar screen or the Radar overlay, select MENU >
Gain.
2
Select Up to raise the gain, until light speckles appear across
the Radar screen.
Radar
Signals).
Adjusting Gain
Adjusting Gain on the
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.
3
Select Down to lower the gain until the speckles disappear.
4
If boats, land, or other targets are within range, select Down
to lower the gain until the targets begin to blink.
5 Select Up to raise the gain until the boats, land, or other
targets appear steadily lit on the Radar screen.
6
Minimize the appearance of nearby large objects, if
necessary.
7
Minimize the appearance of side-lobe echoes, if necessary.

Minimizing Nearby Large-Object Interference

Nearby targets of significant 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.
NOTE: Depending upon the radar in use, the gain setting
configured for use in one radar mode may or may not be
applied to other radar modes or to the Radar overlay.
1
From a Radar screen or the Radar overlay, select MENU >
Gain.
2
Select Down to lower the gain until the smaller targets are
clearly visible on the Radar screen.
Reducing the gain to eliminate nearby large-object
interference may cause smaller or distant targets to blink or
disappear from the Radar screen.

Minimizing Side-Lobe Interference on the Radar Screen

Side-lobe interference may appear to streak outward from a
target in a semi-circular pattern. Side-lobe effects can be
avoided by reducing the gain or reducing the radar range.
NOTE: Depending upon the radar in use, the gain setting
configured for use in one radar mode may or may not be
applied to other radar modes or to the Radar overlay.
1
From a Radar screen or the Radar overlay, select MENU >
Gain.
2
Select Down to lower the gain until the semi-circular,
streaked pattern disappears from the Radar screen.
Reducing the gain to eliminate side-lobe interference may
cause smaller or distant targets to blink or disappear from
the Radar screen.

Adjusting Sea Clutter on the Radar Screen Automatically

You can set the chartplotter to automatically adjust the
appearance of clutter caused by choppy sea conditions.
NOTE: Depending upon the radar in use, the sea clutter setting
configured for use in one radar mode may or may not be
applied to other radar modes or to the radar overlay.
NOTE: Not all options and settings are available on all radar
and chartplotter models.
1
From a radar screen or the radar overlay, select MENU >
Noise Rejection > Sea Clutter.
2
Select Presets or Auto.
3
Select a setting that reflects the present sea conditions.
When using a compatible radar model, the chartplotter adjusts
the sea clutter based on the sea conditions automatically.

Adjusting Rain Clutter on the Radar Screen

You can adjust the appearance of clutter caused by rain.
Reducing the radar range also can minimize rain clutter
(Adjusting the Zoom Scale on the Radar
The rain clutter setting affects the appearance of nearby rain
clutter and targets more than it affects the appearance of distant
rain clutter and targets. A higher rain clutter setting reduces the
appearance of clutter caused by nearby rain, but it can also
reduce or eliminate the appearance of nearby targets.
Screen).
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