Studies on frequency domain acoustic signal detection method with a small aperture sensor array

The noise background of small aperture sensor array is spatial color noise for underwater sonar detection system. A super-directive beamform in frequency domain (FSD) method is proposed to solve the problem that the array gain of super-directive beamform cannot reach maximum when there exists error in the estimated noise matrix under spatial color noise background. The wideband received data are divided into several sub-bands, and noise covariance matrix in each sub-band is estimated, which reduces the error of estimated noise matrix. Estimated noise covariance matrix is used to de-correlate the received data. At last, spatial spectrum detector is employed to detect weak acoustic signal. Experimental results show that the detection performance of FSD is better than super-directive beamform in time domain (TSD) and minimum variance distortionless response in frequency domain (FMVDR) of 2dB.