Oculus M-Series Sonar
User Manual
5
1.
Introduction
Traditionally, sonars were mechanical devices that operated by rotating their transducers (transmitters and
receivers) to scan the sector in front of or around them. At each transducer position, a sound pulse would be
transmitted into the water, and the echoes collected by the receiver before being plotted onto the display.
Depending on the required resolution an image could tens of seconds to update, and any movement of the sonar
during this period could smear and distort the imagery.
Unlike mechanical sonars, Oculus is a multi-beam sonar that has no moving parts, and an array of receivers that
collect echoes from a single transmission pulse and mathematically combine the data into an image using a
process known as “beam
-
forming”.
This allows images to be produced many times per second and viewed in real-
time like the output from a video camera.
Some Oculus sonars (with a ‘d’ suffix at the end of their name) are dual
-frequency, having Low-Frequency and
High-Frequency operating modes that allow the operator to choose between longer acoustic ranges or high-
resolution imagery respectively.
Sonar imagery can take some training and practice to interpret as the display appears to the operator as a top-
down view covering the area in-front of them, acoustically illuminating a sector up to 130° horizontally and 20°
vertically depending on the selected frequency mode. The brightness of targets and textures on the display
represents how much sound has been reflected from them (with gaseous or dense materials reflecting more than
mud, sand and silt), while acoustic shadows can be cast based on the geometry of objects or the seabed.
In the following sections, this manual aims to explain the basics for the correct configuration and operation of the
Sonar, and how to start interpreting the images it produces.
Symbols
Throughout this document the following symbols are used to indicate special precautions or procedures you
should note…
WARNING!
This symbol indicates a warning you should follow to avoid bodily injury or damage to your equipment.
CAUTION
This symbol denotes precautions and procedures you should follow to avoid damage to your equipment.
NOTE
This symbol denotes special instructions or tips that should help you get the best performance from your
equipment.
