Abstract:

A passive underwater acoustic localization method using fractional Fourier transform (FRFT) and focused beamformer is proposed. The directionofarrival and range information of the nearfield broadband linear frequency modulated (LFM) signals can be estimated. The nearfield spherical wave model for broadband LFM signal is introduced and the timevarying array manifold matrix corresponding to the LFM signals is changed into a fixed array manifold matrix by using FRFT. Combined with the nearfield focused beamforming technology and multiple signal characteristics algorithm, the azimuths and distances of multiple broadband LFM signals will be estimated. The validity and efficiency of the proposed method is verified by simulations and experiments, and the performance of the proposed method is discussed in terms of signaltonoise ratio, azimuth and distance of the underwater acoustic signal.