We propose a backscattering compensation based procedure to enhance the performance of multibeam echosounder systems (MBESs). High resolution in a wide field of view is the main benefit of MBESs, and this property makes them increasingly important for measuring scattering in water body. The performance of these systems is vulnerable to the anisotropic characteristics of scatterers, and thus, the results provided by MBESs can be inaccurate. To enhance the performance of MBESs, we compensate for the echo data on the basis of backscattering strength. The compensation considers the reflected sound energy by introducing interlayer coefficients calculated from the amounts of energy that penetrate into and are reflected from each layer. To demonstrate the effectiveness of the proposed method, we perform numerical simulations with randomly positioned scatters having anisotropic properties. Furthermore, anechoic pool experiments are conducted using bubbles generated by air compressors and propellers. The after-compensation results reveal richer details, thereby confirming the effectiveness of the proposed method.

This paper proposes a method for visualizing three-dimensional non-uniformly sampled data from multibeam echosounder systems (MBESs), aimed at addressing the requirements of monitoring complex and dynamic underwater flow fields. To tackle the challenges associated with spatially non-uniform sampling, the proposed method employs linear interpolation along the radial direction and arc length weighted interpolation in the beam direction. This approach ensures consistent resolution of three-dimensional data across the same dimension. Additionally, an opacity transfer function is generated to enhance the visualization performance of the ray casting algorithm. This function leverages data values and gradient information, including the first and second directional derivatives, to suppress the rendering of background and non-interest regions while emphasizing target areas and boundary features. The simulation and experimental results demonstrate that, compared to conventional two-dimensional beam images and three-dimensional images, the proposed algorithm provides a more intuitive and accurate representation of three-dimensional data, offering significant support for the observation and analysis of spatial flow field characteristics.

Underwater target localization using a towed cylindrical array and underwater acoustic communication signals is well-suited for large-area underwater searches, offering high positioning accuracy, operational flexibility, and efficiency. To address the amplitude step artifacts in long target echo signals caused by short-segment time gain control, a signal amplitude compensation method is developed to achieve distortion-free correction. To overcome the limited angular resolution of conventional beamforming, a sliding cylindrical-array beamforming approach based on minimum variance distortionless response (MVDR) is proposed, with the number of array elements involved in each beamforming operation optimized for performance. In addition, to reduce the large variance in target echo arrival-time estimation, a range estimation method is introduced that exploits the fixed gaps inherent in underwater acoustic communication signals, combining energy-gradient detection with segmented matched filtering. Comparative lake and sea trials verify that the proposed target position estimation method delivers high accuracy, strong robustness, and real-time capability.