Research On Passive Detection Technology Based On Vector Hydrophone

Vector hydrophone can co-located in space and simultaneously in time measure the scalar and vector message of the sound field,obtaining more comprehensive observations about the sound filed,which is of great significance to the target detection under low signal-to-noise ratio.Passive sonar system has good concealment,which doesn't need to emission sound waves actively.In order to improve the detection ability for the weak target,the passive sonar system should do the processing of space and time to the received signal,obtaining processing gains in space and time.The passive sonar detection technology of underwater acoustic targets is carried out by using acoustic vector hydrophone in this paper.The main results of the dissertation are as follows:1.In the isotropic noise field,the acoustic energy flow detector is the maximum likelihood ratio detector.The traditional acoustic energy flow detector is designed in the time domain.In this thesis,the representation of acoustic energy flow in frequency domain is obtained.2.Based on the frequency-domain representation of acoustic energy flow,this paper proposes a segmented average cross-spectrum processor(SACSP),firstly,the acoustic pressure and acoustic velocity are segmented and averaged,respectively and then obtaining the cross spectrum which is as the test statistics of the detector.In addition,the probability distribution of the cross spectrum is being deduced,and the simulation results verify the correctness of the derivation.3.The Comparison of detection performance between SACSP detector and conventional average power spectrum processor(AVGPR)is being simulated.The output of SACSP detector has a higher signal-to-noise ratio when the input signal-to-noise ratio is identical.At the same time,the paper also analyzes the difference of the detection probabilities between the two detectors.The simulation results show that the SACSP detector has a higher detection probability under the same false alarm probability and input signal-to-noise ratio.Therefore,the SACSP detector has a higher detection performance than the AVGPR detector.4.The actual noise characteristics of the ocean ambient noise received by the single vector hydrophone are analyzed.The results show that the noise signals obey the Gaussian distribution and are independent with each other,verifying the correctness of ocean ambient noise distribution characteristics when designing the detector.Then using the SACSP detector and AVGPR detector to process the received signal,and comparing their detection performance.The results proves that the SACSP detector has a higher detection capability.