Prediction of far-field radiated acoustic fields in a fluid using near-field acoustic measurements

A method of predicting a far-field radiated acoustic field of a submarine dived in water, the method comprising:

• providing a linear array of acoustic sensors;
• positioning the linear array of acoustic sensors in the water proximate to the submarine;
• radiating into the water, by the submarine whilst the submarine is surfaced in the water such that at least a part of the submarine extends above a surface of the water and at least a part of the submarine extends below the surface of the water, one or more acoustic signals;
• measuring, by the linear array of acoustic sensors, the acoustic signals;
• and
• predicting, by one or more processors operatively coupled to the linear array of acoustic sensors, the far-field radiated acoustic field of the submarine dived in the water using the measurements of the acoustic signals;
• wherein
• the positioning of the linear array of acoustic sensors comprises:
• orienting a longitudinal axis of the linear array of acoustic sensors parallel to a longitudinal axis of the submarine;
• and
• positioning the linear array of acoustic sensors in a near-field region of the submarine, the near-field region of the submarine being a region that is less than or equal to a distance of 2D2/λ from the submarine, where D is a length of the submarine or a part thereof along the longitudinal axis of the submarine and λ is a wavelength of the one or more of the acoustic signals transmitted by the submarine.