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SYSTEM PERFORMANCE AND DATA TYPES
SeaBat T-Series Subsea Operator's Manual Page 60 January 31, 2019
Version 7
7.3 Data Types
7.3.1 Bathymetry Data
The SeaBat T-Series Subsea system generates between 10 and 512 soundings per ping.
The system broadcasts from the sonar processor to the data acquisition software, where they are
corrected for mechanical offsets, motion, heading, refraction, tide or depth, and position. To
perform these corrections, the appropriate sensors must be interfaced to the data acquisition
software. For instructions on sensor configuration, refer to the RESON Sonar UI User Manual
(
see Appendix E Reference Documentation ).
Depending on the beam angle, bottom type, and signal characteristics, the bottom detection
method employed may be magnitude center-of-energy, phase slope zero-crossing, or a blend of
the two methods. The bottom detection method can vary from ping to ping and beam to beam.
7.3.2 Side-Scan Data
Side-scan swath is measured and displayed without degrading any of the traditional survey
capabilities of the SeaBat.
NOTE
Side-scan cannot be used to measure accurate depths, but it can provide a more detailed
picture of the seafloor. This image can be used together with bathymetry to identify features
and to ensure that you do not miss any small but significant targets.
7.3.2.1 Side-Scan Process
The side-scan process averages adjacent pairs of beams to eliminate noise and then carries out
a peak detection over beams from the left and right sides of the swath. The peak detection is
done at the sample rate of the sonar.
The bathymetry and side-scan data are independent in the beamforming process and in how the
output data is generated.
7.3.2.2 Side-Scan Data Output
The array of intensity values is a series of amplitudes, one for each sample interface for each
side-scan beam.
The number of intensity values reported in a side-scan packet is a function of range. The number
of values per packet can be calculated using the following formula:
( 𝑅𝑎𝑛𝑔𝑒
½ 𝑆𝑜𝑢𝑛𝑑𝑉𝑒𝑙𝑜𝑐𝑖𝑡𝑦
)
∗ 𝑆𝑎𝑚𝑝𝑙𝑒𝑅𝑎𝑡𝑒 = 𝑆𝑎𝑚𝑝𝑙𝑒𝑠𝑃𝑒𝑟𝐵𝑒𝑎𝑚
Side-scan is one of the many records available for subscription from the 7k Center software.
Refer to the 7k Data Format Definition for further information regarding side-scan data output
(see also
Appendix E Reference Documentation ).
7.3.3 Snippets Backscatter Data
Snippets backscatter data is available from the SeaBat T-Series Subsea. Each snippet consists of
a windowed selection of amplitudes taken from the bottom detection point of each beam.