Abstract: A blind space spectrum subtraction(BSSS) method based on hyper beam forming for interference cancellation is proposed for two typical near-field strong interference sources (towed-ship self noise and friendly neighbor ship noise) which affect the target detection performance of towed array sonar. The hyper beam technology is used to form multi-beams to cover a strong interference area. The amplitude spectrum of interfering beams is computed, and the multi-beam amplitude spectrum is subtracted from the basic element field amplitude spectrum by using an appropriate spectrum subtraction strategy. The frequency signal of basic element field is get from the cancelled amplitude spectrum signal, and the target azimuth is estimated using the frequency field block adaptive filtering algorithm. The simulation and sea test results show that BSSS method can improve the array gain by about 10 dB compared to the minimal variance distortionless response(MVDR) method under the conditions of high interference-to-noise ratio and low signal-to-noise ratio. BSSS method can be used simultaneously to cancel the towed-ship self noise and the friendly neighbor ship noise, and effectively reduce the fluctuation of detected background.

Key words: acoustics, towed array, hyper beam, blind space, spectrum subtraction, interference cancellation