The radar sweep should commence at your vessel (a radar range of zero). You may need to
adjust the radar range offset to achieve this. If this is set incorrectly, a large dark circle in the
center of the sweep might occur. You might notice straight objects such as straight sea walls
or piers having curves or an indentation. Objects close to your vessel may appear pulled in or
pushed out.
Adjust the range offset as below when the vessel is about 45 to 90 m (50 to 100 yards) from a
straight-walled jetty or similar feature that produces a straight line echo on the display.
• Point the boat towards the jetty
• Adjust the gain setting until a reasonably good image of the jetty echo is displayed
Adjust antenna height
Set the radar scanner height relative to the water surface. The Radar uses this value to
calculate the correct STC settings.
Adjust bearing alignment
This is to align the heading marker on the screen with the center line of the vessel. This will
compensate for any slight misalignment of the scanner during installation. Any inaccuracy
will be evident when using MARPA or chart overlay.
Point the boat to be perpendicular to the very end of a breakwater or peninsula. Adjust the
bearing alignment setting, so that the heading marker and land mass intersect.
Sidelobe suppression
Occasionally false target returns can occur adjacent to strong target returns such as large
ships or container ports. This occurs because not all of the transmitted radar energy can be
focused into a single beam by the radar antenna, a small amount energy is transmitted in
other directions. This energy is referred to as sidelobe energy and occurs in all radar systems.
The returns caused by sidelobes tend to appear as arcs.
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Note: This control should only be adjusted by experienced radar users. Target loss in
harbor environments may occur if this control is not adjusted correctly.
When the radar is mounted where there are metallic objects near the radar, sidelobe energy
increases because the beam focus is degraded. The increased sidelobe returns can be
eliminated using the Sidelobe Suppression control.
By default, this control is set to Auto and normally should not need to be adjusted. However,
if there is significant metallic clutter around the radar, sidelobe suppression may need to be
increased. The control should be adjusted as follows:
1. Set Radar range to between 1/2 nm to 1 nm and Sidelobe Suppression to Auto
2. Take the vessel to a location where sidelobe returns are likely to be seen. Typically, this
would be near a large ship, container port, or metal bridge.
3. Traverse the area until the strongest sidelobe returns are seen.
4. Change Auto sidelobe suppression to OFF then select and adjust the sidelobe
suppression control until the sidelobe returns are just eliminated. You may need to
monitor 5-10 radar sweeps to be sure they have been eliminated.
5. Traverse the area again and readjust if sidelobes returns still occur.
6. Exit the dialog.
Radar sector blanking
(Halo radar only)
Software setup | NSO-evo3 Installation Manual
23
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