JFE-680
JFE-680 Echo Sounder - ProNav
JFE-680 Echo Sounder - ProNav
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Actual Pictures<br />
Seabed<br />
Zero line<br />
DISP TRANS<br />
DISP SURF<br />
DISP KEEL<br />
figure A<br />
Seabed<br />
Zero line<br />
Third reflection of bottom<br />
Second reflection of bottom<br />
Seabed<br />
In case of a shallow seabed or when increasing the amplifier sensitivity, two seabed lines<br />
may be recorded. This results from a multi-reflection of ultra-sonic wave between the<br />
seabed and hull bottom or surface of sea, in such manner: An emitted ultrasonic wave once<br />
reflected at the seabed returns toward the transducer or surface or sea but reflected at the<br />
hull bottom or surface of sea and again reflected at the seabed toward the transducer.<br />
Such multiple recording of the seabed may appear due to change of bottom quality. A<br />
double or triple reflection may be sometimes recorded.<br />
In any case, a first reflection recording from the zero line represents a real seabed return. A<br />
first, second and third reflection lines of seabed arrange with approximately equal spacing on<br />
the recording.<br />
In addition, the shade of the reflection lines fades little by little away from the fast line on the<br />
recording. From these conditions, they can be easily identified as a multireflection.<br />
Appendix 45