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Multibeam Sonars / Overview
A multibeam sonar operates much like a single-beam echo sounder - ensonifying the bottom and detecting echo arrival times.
Unlike the single-beam sonar, which illuminates a single point beneath the sonar, the multibeam sonar illuminates a narrow swath elongated across the bottom and perpendicular to the path of the boat. This illuminated swath is then sampled with multiple, discrete “receive beams” formed by the sonar at known angles. For each beam, the sonar attempts to determine the “best” echo arrival time. With the known beam angle, the determined “best” echo travel-time, and the water-column sound velocity, the cross-track distance and depth can be determined.