Multibeam sonar is a type of active sonar system that is used to scan the seabed and identify items in the water column or on the water’s surface. Together, the sonar’s multiple physical sensors form a transducer array, which broadcasts and receives sound waves that map the seafloor or detect other objects. A multibeam array is often connected directly to the ship’s hull.
How does it work?
In contrast to single beam sonar, which uses a single sensor to scan the bottom, multibeam sonar simultaneously generates a fan-shaped sonar beam pattern (or sound waves). This region encompasses both the area directly beneath the ship and the space on either side. Multibeam collects data in two dimensions: depth to the bottom and backscatter. Bathymetry, or the seabed depth, is calculated by the time required for the sound to leave the array, strike the bottom, and return to the array.
Onboard the ship, scientists measure the speed of sound in the sea they are surveying to translate the ship’s two-way transit time to the bottom to a depth measurement. “Backscatter” is a term that refers to the intensity of the sound echo that returns to the multibeam array.
Backscatter data may be used to estimate the geological makeup of the seafloor or individual objects on it. For example, tougher, stonier materials, such as dirt tend to reflect more sound.
Additionally, multibeam sonars can collect data on the backscatter of sound-reflecting objects in the water column. Backscatter data from the water column may be used to visualize objects hanging in it, such as three-dimensional formations associated with shipwrecks, bubble plumes erupting from the bottom, and dense biological layers.
What happens next?
Onboard computers collect this data, which is subsequently analyzed by hydrographers to create vibrant two- or three-dimensional bathymetric (water depth) maps that help see the bottom. The bathymetric map below uses warmer hues (red and orange) to represent shallower areas, while cooler colors (yellow and green) show deeper areas.
The Critical Role Of Multi-Beam Sonar
Often, the first step in researching a new location is to do a multibeam sonar scan after determining the shape, depth, and character of the seabed. The sediment character identified by multibeam gives information on the species there, aiding in the habitat suitability mapping process. The first multibeam mapping lays the basis for further in-depth investigation and research of our ocean which is how marine construction companies are using sonars.
A Multibeam Sonar is suitable for a wide variety of applications.
- Dredging or building beneath the surface of the sea
- To create a bathymetric map
- The turbidity of the water column is being mapped
- Hydrographic mapping of aquatic environments
- Reconnaissance of cultural relics under the sea
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Multibeam echo sounders profit from the ability to cover the seabed by scanning it with a fan of narrow acoustic beams. The detailed seabed maps created as a consequence are superior to those generated by single-beam mapping. The maps are generated more quickly, which decreases the amount of time spent on ship surveys.
Multibeam sonar is the most efficient method for underwater mapping since it delivers the most amazing findings.