ABSTRACT
In fisheries acoustics, reflective properties of items are usually characterized by sound scattering in the back direction. Two factors are known to affect sound scattering by an item: the dimensions of the item in the direction of acoustic wave propagation; and the sectional area of the scatterer perpendicular to acoustic wave propagation. The indicatrix of the Rayleigh scattering reveals that scattering forward and backward is identical and is twice as large as that in the perpendicular directions. The efficiency of detecting echo signals from commercial items is determined by the minimal intensity of echo signals required for their registration by the receiver against a background of disturbances. Substantial increase in the range of detection of commercial items can also be achieved through the use of modulated by frequency, phase, or amplitude impulses of long duration with a resulting temporal compressing of received signals.
