ACTIVE SONAR USAGE
SeaBat 7125 SV2 Operator‟s Manual
Page 101
July 25, 2011
Version 3
Figure 35: Range Setting
– The Exception
If you are operating in relatively deep water to the limits of operation and the outer
parts of the swath exceed the acoustic range of the sonar, the user should reduce the
swath coverage (see
section 5.7.1.7 Set Vari-Swath
) to cover the seabed that is visible
only. This will increase the ping rate and reduce noise picked up for these visible
beams.
6.2.7 Minimum Beams, Intermediate, and Best Coverage Modes
RESON offer three kinds of beam distribution in a Normal mode (the others being Flex
and Wide modes, see
section 7.1 Beam Modes
) in the SeaBat range of multibeam
echosounders: Minimum Beams, Intermediate, and Best Coverage.
With Minimum Beams the beam center-center angular spacing is constant across the
swath and with Best Coverage the spacing is modified to maintain an equal horizontal
distance between soundings on the seafloor assuming a flat bottom. It is recommended
that Best Coverage be used for general survey applications where the requirement to
achieve a specific number of sounding per cell in the across-track is critical, or where the
seafloor is generally flat.
In areas of significant relief and in particular when surveying features such as wrecks
and vertical structures such as harbor walls, Minimum Beams should be used in
preference to Best Coverage. In extreme conditions, using Best Coverage over complex
structures can cause magnified artifacts due to the large overlap between beams
towards the edge of the sector.
6.2.8 Use of Gates
6.2.8.1 Depth Gates
The depth gates, with no input from a motion sensor, will orient themselves parallel to
the horizontal plane of the sonar head, as shown by the Min and Max Depth lines in
. In this series of illustrations, the bottom detect dots are shown as a horizontal
line (Line A or B) with dashed lines representing depth gates above and below the
bottom and no vessel roll present. Visualize the bottom as being in the „layer‟ formed by
the depth gates.
Summary of Contents for SeaBat 7125 SV2
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