JRC JFE-380 -, Instruction Manual, Page: 76 / 80

Abrupt-Sloped Seabed
Side lobe
False echo
A dim echo may sometimes appear along an abrupt slope of seabed, as if it were floating
above the slope, when recording.
In case of flat seabed, thin second return of seabed may sometimes appear, which is slightly
below the actual seabed.
In either case, the dim or thin echoes are false and produced by side lobes of ultrasonic
beam from the transducer. Any false echo is thinner than and parallel to a real echo.
Appendix 64