146
Raymarine H6 - Owner’s Manual
Multiple echoes
Multiple echoes are not very common but can occur if there is a large target with
a wide vertical surface at a comparatively short range. The transmitted signal will
be reflected back and forth between the target and your own boat, resulting in
multiple echoes, displayed beyond the range of the true target echo, but on the
same bearing.
Blind sectors or shadow effect
Obstructions such as funnels and masts near the radar antenna may obstruct the
radar beam and cause radar shadows or ‘blind sectors’. If the obstruction is
relatively narrow, there will be a reduction of the beam intensity, though not
necessarily a complete cut-off. However, for wider obstructions there may be a
total loss of signal in the shadow area. There may also be multiple echoes which
extend beyond the obstruction. Blind sector effects can normally be minimized by
careful selection of the scanner site prior to installation.
Sea clutter
Radar returns from waves around the boat can
clutter the center of the radar picture, making it
difficult to detect real targets. Such ‘sea clutter’
usually appears as multiple echoes on the display
at short range scales., and the echoes are not
repetitive or consistent in position. With high
winds and extreme conditions, echoes from sea
clutter may cause dense background clutter in the
shape of an almost solid disc.
D1642-1
True echo
Multiple echoes
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Summary of Contents for H6
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