JRC JLN-900 Installation And Instruction Manual page 22

Bottom track reception
Transducer
Hull
S1
Ahead
In some spots the reflectors will cancel each other, while in other spots they will support each
other. The same effect is used in holography, where also both phase and amplitude information
is used. Thus we get a "holographic pattern" on the hull of the ship with loud and silent spots. It
can be shown that the size of a loud spot is typically the same as the transmitter area.
The receivers measure the intensity as they travel over this pattern. One such computer
simulated pattern with only five reflectors can be seen in the figure below.
Hull
S2
Piezo-electric elements
Acoustic beams from reflecting
objects in bottom back to
piezo-electric elements
2-6
Projected bottom area