Parametric Acoustic Arrays

Parametric acoustic array performance has been demonstrated with several different transducers. Three-inch-diameter transducers with primary frequencies between 250 and 300 kHz have produced good parametric acoustic beams at 10, 20, and 40 kHz difference frequencies with nearly constant beamwidth across this frequency band. A parametric acoustic array operating at 20-kHz difference frequency was compared to a 100-kHz conventional transducer for bottom profiling capability in Lake Washington. Echograms were obtained demonstrating the capability of the lower frequency beam to produce subbottom, as well as bottom returns.