Sonar with Multiple Beams
Sonar with Multiple Beams
Multibeam sonar is a form of active sonar system used to scan the seafloor and identify items in the water column or along its surface. The sonar’s numerous physical sensors together are referred to as a transducer array that transmits and receives sound pulses that map the seafloor or identify other objects. Typically, a multibeam array is attached directly to the ship’s hull.
How does it function?
In contrast to single beam sonar, which employs a single transducer to map the bottom, multibeam sonar simultaneously emits several sonar beams (or sound waves) in a fan-shaped pattern. This includes the area directly beneath the ship as well as space on each side. Multibeam gathers two types of data: depth to the bottom and backscatter. Bathymetry, or the seabed depth, is determined by the time it takes 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 water they are surveying to convert the two-way transit time between the ship and the bottom to a depth measurement. Backscatter is a metric that indicates the strength of the sound echo that returns to the multibeam array.
Backscatter data may be used to infer the geological composition of the seabed or items on it. For instance, harder, stony materials tend to reflect more sound than softer materials such as dirt.
Additionally, multibeam sonars may gather backscatter data for objects in the water column that reflect sound. Backscatter data from the water column may be used to show things suspended in the water column, such as three-dimensional structures associated with shipwrecks, bubble plumes emerging from the bottom, and thick biological layers.
What occurs next?
Next question is how can multifrequency bathymetry be applied? Computers on board gather this data, which is then processed by hydrographers to generate colorful two- or three-dimensional bathymetric (water depth) maps that aid in seeing the seabed. The warmer colors (red and orange) in the bathymetric map below indicate shallower places, while the cooler colors (yellow and green) indicate deeper areas.
Importance Of Multi-Beam Sonar
Often, the first step in investigating a new region is to conduct a multibeam sonar scan after identifying the seafloor’s depth, shape, and character. The sediment character determined by multibeam provides information on the species that may reside in the vicinity, assisting in the process of habitat suitability mapping. The initial multibeam mapping provides the groundwork for additional in-depth study and inquiry into our ocean which makes one of the revolutionary sonars for marine construction.
A Multibeam Sonar may be used in a wide variety of situations.
- Dredging or construction below the water’s surface
- Making a bathymetric map
- Mapping the turbidity of the water column
- Aquatic environment hydrographic mapping
- Mapping cultural treasures beneath the sea