An approach to suppress reverberation Doppler spread applied to a small aperture array on the moving platform
When matched-filter processing with velocity channels is applied to Doppler-sensitive pulse echoes on a moving platform,the coupling relationship between velocity and relative bearing leads to reverberation Doppler spread,mak-ing it difficult to detect low-speed targets using velocity information.Based on conventional beamforming,matched-filter processing and own Doppler nullification,a new method that combines split beamforming and velocity matching is presen-ted.The post judgment on phase difference between left and right half-beams in all velocity channels is introduced to sup-press echoes from unexpected bearing,reducing the coupling between velocity and relative bearing.A method for selecting the phase difference interval is provided by deducing the probability density distribution of phase difference between split beams under different signal-to-noise ratios.It is verified by sea trial data that Doppler spread obtained by the new approach is reduced by 50％compared with the conventional method and low-speed weak targets are easier to be identified from strong reverberation.The advantage of this method is greater than that of the conventional method when array aperture is smaller and speed of sonar platform is slower.
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