Research On Target Detection Technology Of Ship Using Vertical Arrays In Shallow Sea

Acoustic signal detection is an important part of the underwater acoustics technology and is one of the hotspots of underwater acoustic engineering research.The ability of the passive sonar system to detect underwater targets is directly affected by the signal detection performance.Ship radiation noise is the target signal source of passive sonar.The ship radiation noise spectrum contains many target parameter feature and motion information,which is the fundamental of underwater target detection.Based on the extraction characteristics of ship radiation noise,this thesis studies the passive detection method of broadband underwater acoustic signals received by multiple vertical arrays in shallow sea.Firstly,the ship noise signal detection method based on spatial dual-station crosscorrelation is studied.These include the power spectrum estimation of ship radiated noise,the estimation of the angle of arrival,the estimation of motion trajectory and the feature extraction of envelope spectrum,and analyze the factors affecting the performance of envelope spectrum extraction.The envelope spectrum extraction method presented in this thesis can extract and separate the envelope spectrum features of specific ships from multiple interference targets,which can effectively solve the problem of multi-objective envelope spectrum aliasing.Secondly,the detection method of shallow sea ship noise target based on single vertical line array is given.On one hand,based on the multi-path angle resolution of the deconvolution beamforming method,the conventional beamforming and deconvolution beamforming algorithms are compared and analyzed for the resolution of the DOA of the multi-path signal and the robustness of the array element mismatch.On the other hand,based on the axialmodulation coefficient extraction of the envelope spectral noise of the ship based on the vertical array,the simulation performance of the modulation coefficient extraction under the condition of shallow sea waveguide is simulated,and the relationship between the modulation coefficient and the moving speed of the ship target is verified by actual data.Finally,the thesis studies the detection range of multi-vertical array targets in shallow seas.Combining the vertical array beamforming technology with the beam domain signal correlation processing,suppressing the interference signal and the multi-path reflection signal,and performing envelope spectrum extraction on the multi-path signal of the ship radiation noise received by the dual vertical array in the shallow sea;The vertical array is extended to multiple vertical arrays,and the propagation loss of the signal is considered.The cross-correlation method is used to determine the target detection range of the multi-vertical array.The ROC curve is used to prove that the single hydrophone is extended to the two recievers,and then extended to the double vertical array,and finally expanded to multiple vertical arrays to detect the ship radiation noise,the detection performance will gradually increase.