Underwater target detection based on fourth-order cumulants beamforming

Abstract

Obtaining the target echo data of high signal to reverberation ratio (SRR) or signal to noise ratio (SNR) in the complex ocean environment is a key problem to improve the detection capability of underwater targets. In this paper, combined with the expansion characteristics of fourth-order cumulants to the array aperture and the structure of the smallest redundant array, a robust and high-resolution fourth-order cumulants beamforming method based on the smallest redundant array is presented. The target direction-of-arrival estimation (DOA) is achieved by forming a narrow space beam, while the reverberation interference is reduced. For the broadband detection system, combined with fractional Fourier transform (FRFT), the fourth-order cumulants beamforming method is extended to the DOA estimation of LFM signal. According to the signal characteristics difference between the target echo and the reverberation, the reverberation is filtered out in the FRFT domain, which achieves the secondary suppression of reverberation interference in the spatial domain and the transform domain, and further improves the SRR of the target echo signal. The validity of the research method is verified by the processing results of the active sonar target detection experiment.