Target depth extraction based on the character of sound field vertical wavenumber spectrum

Passive target classification is a crucial issue in the underwater acoustic domain. The target depth information is a direct evidence of the surface target and underwater target discrimination. This paper focuses on the passive target depth estimation problem. A method of target depth extraction is proposed based on the envelope periodic character of the sound field vertical wavenumber spectrum by the horizontal sonar array. Firstly, a technique to approach the sound field vertical wavenumber spectrum by horizontal arrays is derived. Secondly, the method of target depth extraction by the envelope periodic character of sound field vertical wavenumber spectrum is introduced. Lastly, several numerical simulations of typical conditions are tested. The simulation result shows that, the sound field vertical wavenumber spectrum can be obtained by the method of two dimensions Fourier transform or frequency mathematics analysis. The target depth estimation based on the sound field vertical wavenumber spectrum envelope periodic character by horizontal arrays is valid. Otherwise, the wide-band process to the sound field vertical wavenumber spectrum of wide-band target, the wavenumber definition can be increased, and the precision of target depth extraction curves can also be enhanced. The method proposed by this paper may provide a way to the problem of binary target classification.