Reson SeaBat 7125 ROV, Operator'S Manual

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SYSTEM PERFORMANCE AND DATA TYPES
SeaBat 7125 ROV Operator‟s Manual
Page 103 May 30, 2011
Version 3
7.1.2 Side-Scan Data
Side-scan swath is measured and displayed without degrading any of the traditional
survey capabilities of the SeaBat.
7.1.2.1 Side-Scan Imagery Data
Side-scan forms an image of the seafloor which can be used to locate and identify
features and bottom conditions. Each sonar ping is used to generate a line of data. Each
line contains a series of amplitudes representing the signal return versus time or range.
When a series of these lines is combined and displayed as the vessel moves along the
track, a two-dimensional image is formed, providing a detailed picture of the bottom
along either side of the vessel.
The side-scan data can be viewed on a waterfall display representing the results of a
peak-detect search through the left and right beams of the swath.
NOTE
Side-scan cannot be used to accurately measure true 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 help ensure that the survey does not miss any small but
significant targets.
7.1.2.2 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.
7.1.2.3 Side-Scan Data Output
The array of intensity values is a series of amplitudes, one for each sample interface for
each side-scan beam. A sampling rate of 34482 samples per second provides
approximately one measurement for every 2.5 centimeters of range.
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:
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 C Reference Documentation ).