5 – 3
5.2 Strength of Reflection from Target
The strength of target echo returns depends on component materials and shape of the target as well as height
and size of the target, and the echo returns from a high and large target is not always strong in general.
In particular, coastal lines on the screen are affected by land forms, and, when a low land coastal line
continues, only inland mountain echo returns are displayed on the screen. So the distance to a coastal line
should be measured very carefully.
A mountain to be displayed on the screen.
Coastal line not to be
displayed on the screen.
Fig. 5.3
5.3 Sea Clutters
When the sea is rough, a bright and wide picture appears in the center of the screen. The higher the waves
are, the stronger echo returns. Swirling current is sometimes displayed as smooth as coastal line.
5.4 False Echoes
Pictures of targets which do not exist actually may bother the observer sometimes. The following are
supposed to be causes of such false echoes:
[I] Shadow Effect
When the scanner unit is located in some area, radar waves are reflected with funnel or mast in the
vicinity and targets in the direction may not appear on the screen. To check if there exists any
shadow area, observe where sea clutters are thin and do not exist on the screen. Such shadow area
may appear in the same direction all the time, if any. In this case, you should memorize the direction.
5.2 ~ 5.4
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