![]() ![]() 1,2 Specifically, an active sonar transmits a short pulse to insonify the seafloor and records the backscattered waves repeatedly while it moves along a predefined (usually linear) path to form a synthetic aperture. ![]() Synthetic aperture sonar (SAS) combines coherently the backscattered echoes from successive acoustic pulses (pings) for high-resolution seafloor imaging with application in mine countermeasures, underwater archaeology, or inspection of underwater installations. The potential of the proposed method for high-resolution, narrowband, and limited-aspect SAS imaging is demonstrated with simulated and experimental data. ![]() The resulting SAS image is the consensus outcome of collaborative filtering of the data from each ping. The optimization problem is solved in a distributed and computationally efficient way with an algorithm based on the alternating direction method of multipliers. In this paper, SAS imaging is formulated as an ℓ 1-norm regularized least-squares optimization problem which improves the resolution by promoting a parsimonious representation of the data. Sub-band and limited-view processing, though, degrades the SAS resolution. For example, low frequencies can be partly transmitted through objects or penetrate the seafloor providing information about internal structure and buried objects, while multiple views provide information about the object's shape and dimensions. However, aspect- or frequency-specific information is crucial for improving the performance of automatic target recognition algorithms. Traditionally, object detection and classification tasks rely on high-resolution seafloor mapping achieved with widebeam, broadband SAS systems. Synthetic aperture sonar (SAS) provides high-resolution acoustic imaging by processing coherently the backscattered acoustic signal recorded over consecutive pings. ![]()
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