With a 1M^2 array, would all 4,000 transducers need to be active simultaneously to achieve 155db? I ask because it seems part of their core IP is the beamforming technology, which could mean physically steering the transducers towards the receiver, or only activating those transducers which point directly at the receiver.
Yes, they'd all be active, and at the same frequency, but in different phases. Beam forming is done by adjusting the phase of each transmitting element so that all the elements are in phase relative to a surface aimed at the target. See [1]. Each transducer has a relatively wide output dispersion, but the entire array produces a much tighter beam. This is a standard technology for radio, radar, and sonar.
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