Broadband underwater target echo detectionbased on signal spectral irregularity feature

For the detection of underwater target echo under strong interferences, the modulation feature of direct echo signal and reverberation spectrum are characterized by the signal spectral irregularity feature, and the relationship between signal spectral irregularity and target physical properties is theoretically formed. A novel method of broadband underwater target echo detection under reverberation based on the signal spectral irregularity characteristics is proposed. The proposed method has the capability of discriminating between the direct target echo signal from reverberation. Simulation results of complex underwater target broadband acoustic scattering show that the echo can be detected even with the signal to reverberation ratio(SRR)below -10 dB by the proposed method based on the spectral irregularity(SI)feature. The corresponding sea experimental results also show that echo can be detected when the SRR is below 0 dB. The effectiveness and correctness of the proposed method are verified both in simulated data and in real data in sea experiment.