Introduction to Side Scan SONAR
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© 2013 Marine Sonic Technology, Ltd.
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Introduction to Side Scan SONAR
2.1
General SONAR Overview
SONAR is a coined word derived from the phrase, SOund Navigation And Ranging. SONAR
generally refers to a system that uses acoustical (sound) energy transmitted through water. At the
heart of that system is the transducer, the device that converts electrical energy to sound and vice
versa and is responsible for generating the sound pulse. A receiving transducer is used to receive
the echo that “bounces” off objects encountered along its path
The transducer sends out a sound
pulse
The pulse bounces off the object
Thus, SONAR is a system that determines the position of unseen underwater objects by
transmitting sound waves and measuring the time it takes for their echo to return after hitting the
object.
2.2
How Side Scan SONAR Works
Because of their flexibility, side-scan systems can be used in many applications , some of which
involve highly sophisticated remotely operated vehicles (ROVs) or autonomous underwater vehicles
(AUVs). But the most common side-scan systems are towed behind a surface vessel and comprise
three elements: the control unit containing the software, the towfish with transducers mounted
on each side, and the cable that connects the towfish to the surface vessel that follows a track or
course through the water. The images they create can be used for many applications such as
geologic studies, locating sunken objects, ensuring that the waterway is clear and safe for shipping,
and many more.
The transducer assembly is towed on a steady course and at a constant depth through the water.
As it is towed, the assembly emits sound pulses at precise and regulated intervals.
