Radar Problems - Simrad NX40 Installation & Operation Manual

the unit's ability to find the bottom or
other targets. This often happens when
the boat is reversed. The transducer
must be mounted in a smooth flow of
water in order for the unit to work at all
boat speeds.
• Electrical noise from the boat's motor
can interfere with the unit. Try some
suppression spark plugs.
4-5 There is a double bottom trace
shown:
• The boat may be in an area that
generates shadows.
• In shallow water, the echoes may
bounce. Reduce the gain setting and/or
reduce the echosounder pulse power.
• Decrease the Range.
B-5 Radar problems
5-1 Radar overlay doesn't appear on
the chart screen
• Ensure that your boat is shown on the
radar window. If it is, but the radar
overlay still isn't shown, try zooming in
on the charted area. (The charted area
may be outside the maximum range of
the radar).
• The threshold or transparency settings
for the radar overlay are not correct
(see 18-6).
5-2 Radar shows arcs and/or shadows
• Side lobe patterns often appear as an
arc or a broken arc. Shadows are blind
spots.
• If the radar is installed at a suitable
height and in a suitable location on your
boat, side lobe patterns and shadows
caused by obstructions such as funnels
or masts will be minimized.
• If you are having problems with these,
you may need to relocate your radar.
Consult the Installation Guide for your
radar model for advice.
5-3 Radar shows different patterns on
each sweep
• Interference patterns always appear
in a different place with each sweep.
Simrad NX40/45 Installation and Operation Manual
They can be randomly scattered bright
dots or dotted lines that extend from
the center to the edge of the radar
window, often producing a spiral effect.
Generally, the stronger the interference,
the wider the interference lines.
• Use the interference rejection feature
to reduce interference patterns, and
the width of the interference lines (see
18-4).
5-4 Radar shows false echoes and/or
background noise
• False echoes and/or background noise
can be produced if the radar sensitivity
is too high.
• Try using the Auto setting for the radar
gain mode (see 18-4). If this doesn't
work, or if the radar gain mode is
already set to Auto, use the radar gain
setting to reduce the radar sensitivity
5-6 Radar shows multiple echoes off
the same object
• Multiple echoes off the same object are
most likely to occur when you are close
to a large target, and are usually only a
temporary nuisance.
5-7 Radar shows random or grouped
dots
• Rain clutter often appears as random
dots that can merge into badly-defined
echoes on the radar window. The
random signals are returned from rain,
hail, sleet, or snow and can result in a
confusing display
5-8 Radar shows random signals in
center
• Sea clutter
confusing, random
your boat. High waves will produce the
maximum amount of sea clutter.
• You can optimize your radar window to
reduce the effects of sea clutter.
usually appears
signals around
as
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