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The Study Of The High Resolution DOA Estimation Technology Based On The Acoustic Vector Array

Posted on:2005-11-01Degree:DoctorType:Dissertation
Country:ChinaCandidate:H D XuFull Text:PDF
GTID:1102360155968753Subject:Underwater Acoustics
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It is well known that the sound wave has both scalar quantity and vector field, and pressure is scalar, particle velocity is vector. The acoustic vector hydrophone is a new type sensor, which can simultaneously measure the pressure and particle velocity of the same point in acoustic field. The theoritic analysis and sea experiments proved that in the far field condition, the pressure of coherent source is correlated with its particle velocity, the latter has a natural dipole direction independent of frequency. It is also proved that the pressure of ambient noise is irrelevant with its particle velocity. This is the physical fundament of acoustic vector signal processing.A single acoustic vector sensor gives more information of sound field, many research work based on a single acoustic vector sensor have been carried out and many active results are obtained. But how about an acoustic vector array? It is urgent to be investigated. Combined with the traditional pressure array processing theory, beam-forming algorithms and high resolution Direction-of-Arrival (DOA) algorithms based on acoustic vector array are proposed in this thesis, the main contributions are as follows:1. The output of an acoustic vector array can be described as a kronecker tensor product of the pressure output and a vector, which is only correlated with the DOA of source. That means the manifold of the acoustic vector array is the kronecker tensor product of the pressure array manifold and a vector pointed to the source DOA.2. The beam-former output of arbitrary geometry acoustic vector array equal to the product of the same geometry pressure array output and a weight coefficient which is independent of array geometry. This coefficient, however, is the scalar product of the source DOA vector and the steering vector. Just because of this weight coefficient, an simple acoustic unit line array (ULA) can unambiguously determine the source azimuth and elevation angle.3. Operation in element-space, acoustic vector array offers no much more advantages over pressure array in SNR resolution threshold and angle resolution. By utilizing the characteristic that the ambient noise pressure is irrelevant to the ambient noise particle velocity, the input SNR is enhanced by the traditional beam-forming algorithms. So the beam-space high-resolution DOA algorithms based on acoustic vector array is superior both in SNR resolution threshold and angle resolution to the same operation with pressure array. At the same time, operation in beam-space, the computation complexity of beam-space acoustic vector high-resolution algorithms isreduced to the same level as beam-space pressure high-resolution algorithms.4. The particle velocity output of a 2-D acoustic vector sensor can be described by an analytic function, which we call it analytic particle velocity. Its complex modulus equal to the pressure, complex phase angle equal to the source DOA. So the output of a 2-D acoustic vector array can be divided into two parts: the pressure vector and analytic particle velocity vector, the latter equal to the product of the pressure vector and a rotation matrix. The rotation matrix, however, is a dialog matrix, whose elements only lies on the source DOA, so the ESPRIT algorithm can be used to estimate the source DOA. Compared to the traditional ESPRIT algorithms based on pressure array, the new ESPRIT algorithm based on acoustic vector array ha no restriction on array geometry and has no aperture loss.In the last chapter, the lake experiments data and sea experiment data have been processed using the algorithms proposed in the thesis. The process result accord with the experiment, correct azimuth-time displays are presented.
Keywords/Search Tags:acoustic vector sensor, beam-forming, array signal processing, high resolution DOA estimation
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