Blueprint Subsea M1200d, Руководство пользователя

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Oculus M-Series Sonar
User Manual
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3.6. Understanding Echoes
Although it has been mentioned that the sonar display can be thought of as a top-down image of the area in front
of them, there are some limitations to this analogy.
As the image is illuminated from the side by the sonar, only the edges or faces of targets closest to the sonar will
be illuminated.
If a target face is at an angle, then some of the incoming sound waves will be reflected towards the sonar while
others will be scattered away in different directions and the overall brightness of the target will be reduced.
The figure below illustrates this, highlighting in red the areas on three simple targets that will appear brightest on
the display, and how these appear from real-world targets:

Car Tyre

1m Hollow Cube
These same principles also apply to larger
environments. The figure opposite shows how some
of the features found in docks or harbours may
appear.
Depending on the orientation of the sonar, corrugated
pilings will have small areas of shadow, and bright
returns from the edges facing the diver.
Concrete walls and quays will also produce bright
returns from flat surfaces, but can also have large
areas of shadow behind parts of the structure.