Use Of Gates; Figure 9: Graphic Illustration Of Flexmode - Teledyne SeaBat T Series Operator's Manual

ACTIVE SONAR USAGE
6.2.9.2 FlexMode 8
 Designed for pipeline or umbilical profiling. Provides equidistant beam spacing for the
full swath coverage together with a high-density equiangular sector which may be
steered toward the detail area of interest.
 In this mode the system is started with a 140° wedge and an alternative beam
distribution is used which concentrates the majority of beams into a central sector.
FlexMode provides a combination of a high density of beams on and around the object location
and a reduced density of soundings for the rest of the swath. The low-density spacing is defined
by the operator (with the slider for Constant seafloor spacing) and the high-density spacing is
computed by optimization based on survey parameters.
For instructions on how to adjust this setting, refer to the RESON Sonar UI User Manual (see
Appendix E Reference Documentation).

6.2.10 Use of Gates

Applying range and/or depth gates to the bottom detection process aids in noise reduction and
correcting for a tilted sonar head.
 No Gates: The bottom detection process searches the entirety of each beam for the bottom.
 Absolute Gates:
8 FlexMode is an optional add-on feature (see Table 1).
SeaBat T-Series Subsea Operator's Manual
Version 7
Low density
sector

Figure 9: Graphic Illustration of FlexMode

Depth: Forces bottom detection to occur within the Min/Max Depth limits set. If
o
the seabed falls outside the limits, bathymetry data will fail and cannot be
recovered.
Range: Forces bottom detection to occur within the Min/Max Range limits set. If
o
the seabed falls outside the limits, bathymetry data will fail and cannot be
recovered.
30%
High density Low density
sector
Total swath
Page 39
Default settings
Total swath: 90°
High density sector: 45° centered
Altitude: 5m
DTM density: 0.1m
sector
January 31, 2019