Artemis BP00707, Руководство пользователя

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Acoustic Shadows
Similar to an object casting a shadow when illuminated with a narrow torch beam,
underwater targets can cast “acoustic shadows” in the sound beam, meaning any
further targets behind them will not be visible if they lie fully within the shadow.
The figure below show a selection of spherical and rectangular targets in the sonar’s
field of vision. As well as the shadows they create, the leading edges of the targets
have been highlighted to surfaces the sound is reflected from, and ultimately this is
what is shown on the display…
If a target is partly obscured by another target in front of it, the returns echo will be a
combination of the horizontal profile of both targets, and this can be seen in the “Sonar
Display” in the figure above.
Vertical Targets
As the sonar only scans horizontally, is cannot determine if a target lies above or below
it, and this means no vertical information is available to the operator.
If two targets are positioned along the same scan angle with one vertically above the
other at the same range from the sonar, then the sonar will not be able to tell the two
apart, and their echoes will merge into one result on the image, with the more
reflective target being dominant on the display.
However, by moving location, the echoes will separate and both targets will become
visible.