Theoretical and experimental study on multibeam synthetic aperture sonar

Abstract

High-resolution imaging method is one of the researching focuses of underwater acoustic detection. Underwater small-target detection also requires detailed imaging technology. Multibeam echo sounders (MBESs) and synthetic aperture sonar (SAS) are the effective instruments widely researched to obtain underwater acoustic images. Constrained by the theory, the along-track resolution of MBES decreases with distance and the gaps problem of SAS always exists and both inevitably limit the quality of acoustic imaging. In this paper, a two dimensional multibeam synthetic aperture sonar (MBSAS) model is designed to overcome the shortcomings of conventional underwater imaging instruments. MBSAS can provide a three dimensional (3D) high-resolution acoustic image without a gap problem. An echo model and transducer array manifold are designed to meet the requirements of engineering applications. Imaging theory and target simulations prove the feasibility of the MBSAS model. The performance of the proposed model is demonstrated with a tank experiment. A detailed image is obtained through an experiment that can indicate the shapes of targets and has the ability to separate adjacent targets. The simulations and experimental results indicate that MBSAS can obtain a more detailed 3D full-scan image than conventional MBES and SAS system with a better energy focusing ability.

Super Resolution by Deep Learning Improves Boulder Detection in Side Scan Sonar Backscatter Mosaics

“…The typical resolution of backscatter mosaics in practical applications in the German Baltic Sea and North Sea is 0.25 m to 1.0 m. This is in contrast to the aims of European habitat mapping guidelines to describe all objects exceeding a diameter of 0.063 m, the sedimentological transition from gravel to cobbles, as potential hard ground that needs to be detected [5]. Obviously, objects of such size cannot be detected in currently available datasets, and the widespread application of new technology such as synthetic aperture sonar [7], strongly increasing the resolution of bathymetric grids and backscatter intensity mosaics especially in the along-track direction, is required.…”

Obtaining 3D High-Resolution Underwater Acoustic Images by Synthesizing Virtual Aperture on the 2D Transducer Array of Multibeam Echo Sounder

“…where t d (t, r T ) = 2 r (t) − r T /c is the time-delay of the SAS echo, which is the vector expression of τ k (n); and r (t) is the vector of the carrier and r T is the vector of the target, which is processed in the synthetic aperture period Γ. r (t) is the analytic vector in the 3D space and performs scalar in the range and time delay as r. The center frequency of the echo is expressed as f 0 , and B is the bandwidth of the LFM echo. The single-element imaging output of SAS processing is shown in Equation 14, which has been solved analytically [22] I(y, r)…”

An ultrasonic multi-wave focusing and imaging method for linear phased arrays*

“…Nowadays, ultrasonic imaging with phased arrays is an important technology and is widely applied in various fields, including non-destructive testing (NDT), [1][2][3][4] sonar, [5,6] medical diagnosis [7][8][9] and so on. With rapid development of the technology, the industry makes higher requirements for imaging resolution in NDT.…”