JRC JMA-9172-SA, Instruction Manual

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JMA-9172-SA Instruction Manual
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6.TRUE AND FALSE ECHOES ON DISPLAY
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6.2 STRENGTH OF REFLECTION FROM THE
TARGET
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6
6.2
STRENGTH OF REFLECTION FROM
THE TARGET
The signal intensity reflected from a target depends not only on the height and size
of the target but also on its material and shape. The echo intensity from a higher
and larger target is not always higher in general.
In particular, the echo from a coast line is affected by the geographic conditions of
the coast. If the coast has a very gentle slop, the echo from a mountain of the
inland appears on the radar display.(Fig 6-3) Therefore, the distance to the coast
line should be measured carefully.
Fig 6-3: Sea shore line which is not displayed
Table 6-1 shows the graph indicating the relation between the target detection
distance and the radar reflection cross-sectional area (RCS) with regard to the type
and the height of the target in a situation in which the weather is good, the sea
state is calm and the radio wave propagation is normal. As revealed by this table,
even on the same sea shore line, detection distance greatly differs depending on
the height of the target from the surface of the sea. Furthermore, because the
target detection distance is greatly influenced by the shape and material of the
target and environmental conditions, such as the sea state, weather, and radio
wave propagation, caution should be taken when detecting distance of target.
Mountain displayed
on the radar display
Sea shore line not displayed
HL