Esipov I. B., K. A. Naugolnykh and V. Timoshenko (April 2010): The parametric array and long-range ocean research. Acoust. Today, 6 (2), 20-26. doi:10.1121/1.3467644Full text not available from this repository.
Parametric array systems are a promising tool for multifrequency acoustical tomography techniques for monitoring range dependent temperatures and current distributions in a complex ocean environment.The parametric array (PA) is a nonlinear transduction process that can generate a narrow beam of low frequency sound in a medium, through the interaction of co‐linear, intense, high frequency sound waves, called pump waves. The unique characteristic of a parametric array is found in its extremely narrow directivity pattern (1°–3° angular resolution) for low frequency acoustical signals. The effective width of the directivity pattern remains practically constant over a wide range of signal frequencies. The parametric array has become essentially a virtual acoustic end‐fire array that has been formed in the medium (water) by the non‐linear interaction of the two high frequency waves at their sum and difference frequencies. As a result, it radiates a sharp, low‐frequency, directional signal at the interaction frequency of its pump waves that propagates independently of the pump waves.
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