Collecting Multibeam Sonar Data

October 1, 2010



Multibeam sonar systems emit sound waves from directly beneath a ship's hull to produce fan-shaped coverage of the sea floor. These systems measure and record the time elapsed between the emissions of the signal from the transducers to the sea floor or object and back again. Multibeam sonar’s produce a 'swath' of soundings (i.e., depths) to ensure full coverage of an area.

A unique aspect of multibeam sonar is the integration of vessel attitude into the collection of the data. This is accomplished through a Global Positioning System and data from an Inertial Motion Unit (IMU). The IMU makes very precise measurements of vessel attitude many times per second. By integrating attitude measurements with the timing of the sonar echo, an accurate bathymetric record can be produced regardless of the echo path through the water. This aspect of multibeam technology makes it the most complicated sonar system and the most expensive to operate.

This system is compare to the one that we studied in Chapter 6 of our textbook.  The scientists use sounding to denote a sequence of measurements obtained at various altitudes in the atmosphere.