Defocusing beamformer method and system for a towed sonar array

摘要

A method and towed sonic array system for defocusing the beampattern of the towed sonic array. The method includes determining an amplitude adjustment and a phase adjustment for each of the sonic projectors; and driving each of the sonic projectors with a drive signal modified by the amplitude adjustment and the phase adjustment for that sonic projector. The amplitude adjustment and phase adjustment for each of the sonic projectors are, at least in part, based upon the distance from that sonic projector to a virtual source. The location of the virtual source may be selected so as to achieve different beampatterns, including wide-sector beams and, in at least one case, a near-omni-directional beampattern. The drive signal may include multiple frequency components, in which case the method may be used to find a set of beamformer coefficients for each of the frequency components and an inverse transform may be used to realize a defocused driving signal.

主权项

1. A towed sonic array system, comprising:
a linear array of sonic projectors; a linear array of receivers; and a control system configured to drive the sonic projectors, wherein the control system is configured to drive each of the sonic projectors with a drive signal modified by an amplitude adjustment and a phase adjustment for that sonic projector, wherein the control system includes a memory containing a beamformer coefficient for each sonic projector, each beamformer coefficient comprising the amplitude adjustment and phase adjustment for its respective sonic projector, and wherein the beamformer coefficients have been obtained using the expression:B_n=(R0Rsn)⁢ⅇ-ⅈ⁢⁢k⁢⁢Rsn wherein n is an index from 1 to the number of projectors, the beamformer coefficients are Bn, R0 is a coefficient to normalize the beamformer coefficients to the range 0 to 1, Rsn is the distance from the virtual source to sonic projector n, and k is a wave vector given by k=2π/λ, wherein λ is an acoustic wavelength given by λ=c/f wherein f is the frequency of the drive signal and c is the speed of sound.