Theoretical And Experimental Study On Underwater Acoustic Array Processing

Array signal processing plays a very important role in various applicationfields With the development of sensor and array technology,it has been a populartopic in recent years In this paper,several algorithms are improved to enhancetheir capabilities for target detecting,bearing resolution and DOA estimatingSpatial match filter is the optimal processor under maximum signal to noiseratio(SNR)criterion in mono-source and white noise condition The noise can besuppressed to a certain extend by tilting the array snapshots with Wiener filterwhich is under minimum mean-square error criterion To carry out spatial noisecmaceling,the Wiener filter is constructed through Second-Order ConeProgramming(SOCP)The algorithm is then compared with maximum likelihoodestimating(MLE)and Bartlett beamforming through simulation The SNRthreshold of Spatial filter is lower than maximum likelihood method in DOAestimation,and the detection performance is better at low SNR So it is a excellentprocessor in mono-source mad white noise conditionMinimum Variance Distortionless Response(MVDR)is the optimalprocessor under minimum power of beam output and distortionless responsecriterion Its constraints can be transformed to second-order cone forms L,norlTl constraint Minimum Variance Distortionless Response。-MVDR)isproposed by minimizing L,norlTl instead of L2 norlTl of the power minimizingconstraint in MVDR The weights generated by L,-MVDR repress interferesbetter than MVDR,which is the cause of a better bearing resolution Analyse therobustness of both algorithms comparatively The disturbance of array modelaffects beamformings'behaviors With the increase of the disturbance,L,-MVDR deteriorates more rapidly than MVDR So L,-MVDR sacrifices itsrobustness to gain better resolution ability．Acoustic vector-sensor array STeered Minimum Variancebeamforming(VSTMV)is propounded A comparative analysis of Bartlett Incoherent Minimum Variance(ICMV)mad Spatially Resmnpled MinimumVariance(SRMV)beamforming algorithms based on vector uniform line aiTa iscarried out Then several aspects are analysis such as directivity,port／staxboarddistinguishing,width of mainlobe,sidelobe levee spatial undersamplingperformance,bearing resolution,resolution of correlated sources mad weak sourcedetecting ability under s~ong interferes Finally sea trial real data is maalysed withthese algorithms comparatively Cross-spe~rM density matrix estimated will notbe accurate with the direction of the target changing caused by its moving,whichleads to beamforming performance'S degenerating So that,STMV with fasterconvergent speed has better performanceVariance of Instantaneous Frequency-Beamforming detector(VIF-BF)isintroduced to improve the detecting ability of targets that radiate line spectrumsignal for three--dimensional time--bearing display,by taking advantage of highSNR prope~y of line spectrum First,the form for the variance of instantaneousfrequency estimating through short-time Fourier Transform(STFT)is derived．and is verified with Monte Carlo simulation The beamforming outputs of thebearings where the targets that radiate line spectrum signal are will bes~enghened,and vice versa Therefore the detecting capacity is enhancedVariance of instantaneous~equency-CBF beamforming detector and variance ofinstantaneous~equency-STMV beamforming detector are simulation as aexample The behavior of multiplicative inverse method and exponentiN weightmethod is also studied Its validity is proved by three sea trial...