how the beam formation is done in sonar?

Question

beam formation in underwater sonars,what happens when the no of stave increased? shape of the sonar beam etc.

Answer 1

Side-scan sonars are the most common of the high-frequency sonars available, and are used for object detection and mapping of the sea-bed. These sonars have a narrow along-track beamwidth and a broad vertical beamwidth. As usual, the range resolution is determined by the pulse length, therefore the sonar receiver has to have a sufficiently wide bandwidth; the scanning rate is also significant as is the altitude of operation, which affect shadow formation and subsequent interpretation.

side-scan sonars, with a typical operating frequency of 100kHz, horizontal beamwidth between 0.75deg and 1.5deg, vertical beamwidth between 35deg and 65deg, pulse length of 7.5cm and range scales out to 500 or 600m. These sonars in general could be mounted on a vehicle moving up to 15 knots. These typical side-scan sonars include EDO-601, EDO-606A manufactured by EDO Western; Multi-Scan 1500 by Ferranti Ocean Res. Eq.; the SeaMarc I & SeaMarc CL sonars by I.S.T. Inc, and most of the 422 series manufactured by Klien. All of these side-scan sonars use 1D linear arrays and no electronic beamforming, without focusing. Only the CMK-1 Shadowgraph by Westinghouse and the SLS-010 by Sonatech Inc are focused. The latter (SLS-010) focuses using a digital beamformer. The SLS-010 can operate simultaneously at several different frequencies (ie.100kHz and 600kHz) and can also apply variable beam array centre beamforming. Multi-beam beamforming is achieved using phase shifts instead of true time-delays, and a phase correction term is used to compensate for wavefront curvature (focus).

Answer 2

Typically it's done with multiple transducers and the phase between them is adjusted to form and direct the beam