Frequency Band Expansion Method of Subband Peak Energy Detection Based on Hough Transform

Passive sonar wideband surveillance is often used to monitor the wideband radiation noise of naval ships in space and estimate the direction of arrival. In engineering, the operating frequency band is generally selected below the half-wave frequency, which means the half-wave array is arranged according to the highest operating frequency. The extended frequency band greater than the half-wave frequency is not used for detection due to the influence of grating lobe. A passive sonar wideband surveillance band expansion method is proposed in this paper. On the basis of existing beamforming, this method combines Hough transform and subband peak energy detection (SPED) to process the beam domain data with a frequency greater than half wave frequency. The azimuth of the desired lobe peak at each frequency point is consistent, but the grating lobe does not. The method first uses Hough transform to extract the straight line formed by the subband peak, and the grating lobe peak can be effectively eliminated by removing the peak point outside the straight line. Then the reserved peak energy is accumulated, which can effectively suppress the influence of grating lobes on bearing time recorder (BTR) and detection in the extended band. The effectiveness of the method is verified by computer simulation and actual test data analysis. This method can extend the integrated frequency band of sonar to more than half wave frequency without introducing grating lobe interference, and increase the available frequency range of sonar broadband, which has certain engineering application value.