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HOW TO DISTINGUISH THE NATURE OF BOTTOM
There are different natures of bottom such as rock, sand, mud or etc.
In case you distinguish the nature of bottom, you judge from the thickness of bottom
image and the situation of second reflection. At the hard bottom like rock, reflection of
transmitted wave becomes strong and bottom image becomes thick and the second
reflection becomes easily to appear. On the other hand, at the soft bottom like sand or
mud the reflection becomes weak and bottom image becomes thin and the second
reflection becomes hard to appear.
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Second reflection…….Ultrasonic wave transmitted from transducer is reflected from
sea bottom and then it is reflected from both sea surface and bottom finally. In short,
second reflection is image of two round-trips between sea surface and bottom.
Second reflection
Rock
Sand or mud
