Author:  Li, Yiu Lung 
Title:  Direction finding using a pair of orthogonally orientated velocity/pressure sensors 
Degree:  M.Sc. 
Year:  2013 
Subject:  Detectors. Hong Kong Polytechnic University  Dissertations 
Department:  Faculty of Engineering 
Pages:  v, 27 leaves ; 30 cm. 
Language:  English 
OneSearch:  https://www.lib.polyu.edu.hk/bib/b2643477 
URI:  http://theses.lib.polyu.edu.hk/handle/200/7127 
Abstract:  An acoustic vectorsensor, also known as vector hydrophone, plays the main role in DirectionofArrival (DOA) estimation because acoustic vectorsensor measures the incident acoustic particlevelocity field for more accurate estimation and has smaller size than the traditional microphone. Typically, vector hydrophone is constituted by a triad of three identical acoustic particlevelocity sensors, which are orthogonally orientated but collocated at the Cartesian origin as a pointlike geometry, plus an optional acoustic pressure sensor. There are only two unknowns to be estimated in the AngleofArrival (AOA) Estimation, the elevationangleofarrival (θ) from the positive zaxis and the azimuthangleofarrival (α) measured from the positive xaxis. So, the number of sensors can be reduced to two, which can be a pressure sensor or particlevelocity sensors orientated on any Cartesian axis. In addition, complex and precise manufacture processes are required to compact all the particlevelocity sensors into a pointlike geometry. If sensors are displaced, they are easier to be fabricated. Also, the separation between two sensors introduces a spatial phase factor, providing more direction information for estimation. Therefore a pair of displaced sensors is proposed in this dissertation for AngleofArrival (AOA) Estimation in order to have a simpler sensorarray structure and lower hardware implantation cost. There exist 30 possible sensor pair configurations which have different sensors combinations at different spatial orientation. This dissertation introduces the closedform formulas for each of these configurations to estimate the angleofarrival of incident source. The required prior information on the validityregions for unambiguous estimation to the azimuthelevation arriveangle is also identified. 
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