6-10
6.4 False Echoes
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[III] False Echo by Secondary Reflection
When a target exists near own ship, two echoes from the single target may appear on the radar display.
One of those echoes is the direct echo return from the target and the other is the secondary reflection return
from a mast or funnel that stands in the same direction as shown in Figure 6.7
Radar
scanner
Funnel
HL
Direct microwave
Secondary reflection
of microwave
Actual target
False echo from funnel
Figure 6.7 False echo by secondary reflection
[IV] False Echo by Multiple Reflection
When there is a large structure or ship with a high vertical surface near own ship as shown in Figure 6.8,
multiple refection returns may appear on the radar display. These echoes appear in the same intervals, of
which the nearest echo is the true echo of the target.
Figure 6.8 False echo by multiple reflection