Use Of Beam Modes; Figure 8: Outer Beams For The Different Beam Modes With A Tilted Sonar Head - Teledyne SeaBat T Series Operator's Manual

ACTIVE SONAR USAGE
6.2.8.4 Minimum Grazing Angle
The minimum grazing angle is a limitation for the non-equiangular beam modes of the sonar. This
limitation is especially noticeable for a sonar with a tilted head (see section 6.3.4 below).
With a tilted head for Equi-Angle beam mode, there is no minimum grazing angle and the outer
beams can look 'upwards'. With a tilted head for the other beam modes the sonar is limited and
cannot look 'upwards'.
For the beam mode Intermediate, the minimum grazing angle is 5°, and for Equi-Distant and
FlexMode, the angle is 15°. For these three beam modes the outer beam cannot go higher.
Figure 8 provides a graphic illustration of the minimum grazing angle.
Minimum
Grazing
Angle

Figure 8: Outer Beams for the Different Beam Modes with a Tilted Sonar Head

When you want to look up with a tilted sonar head you have to select Equi-Angle beam mode.

6.2.9 Use of Beam Modes

The following beamforming modes are available: Equi-Distant, Equi-Angle, Intermediate, and
FlexMode (optional).
The system allows everything from high-density beams for exceptional image clarity and detail to
just a few beams to deliver results faster. By deploying fewer beams in shallow water, the system
allows the user to reduce storage requirements by gathering only the data you need. The system
can also hold constant seafloor spacing between beams to provide the same high-quality results
with minimal data volume.
SeaBat T-Series Subsea Operator's Manual
Version 7
NOTE
Page 37 January 31, 2019