Radar

Manually Adjusting Gain on the Radar Screen

For optimal radar performance that accounts for actual conditions, 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 (page 63).

1.From the Home screen, select Radar.

2.Select Cruising, Harbor, Offshore, or Sentry mode.

3.Select Menu > Gain.

4.Select Up 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 Down to lower the gain until the speckles disappear.

6.If boats, land, or other targets are within range, select Down to lower the gain until the targets begin to blink.

7.Select Up 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 64).

9.If necessary, minimize the appearance of side-lobe echoes (page 64).

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 (page 63).

1.From the Home screen, select Radar.

2.Select Cruising, Harbor, Offshore, or Sentry mode.

3.Select Menu > Gain.

4.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 more-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 (page 63).

1.From the Home screen, select Radar.

2.Select Cruising, Harbor, Offshore, or Sentry mode.

3.Select Menu > Gain.

4.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 more-distant targets to blink or disappear from the Radar screen.

Restoring the Default Sea Clutter Setting

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 (page 63).

1.From the Home screen, select Radar.

2.Select Cruising, Harbor, Offshore, or Sentry mode.

3.Select Menu > Noise Rejection > Sea Clutter > Presets.

4.Select a setting that reflects present sea conditions: Rough, Medium, or Calm.

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GPSMAP 700 Series Owner’s Manual