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A linear array can only identify the incident angles of
radiated sources which are coplanar with the array. However,
the signal sources may not always be on the same plane as the
array laid. Simple algorithms for estimating direction of
arrival (DOA) of signal sources positioned in three dimensions
can be obtained by taking advantage of two linear arrays. In
this thesis, techniques of two-dimensional (2D) bearing
estmation of underwater signal sources using linear hydrophone
arrays are studied. For narrow-band emitter signals, a method
of 2D-DOA estimation, which combines the MUSIC and ESPRIT
algorithms, is discussed first. We use MUSIC method to estimate
the DOA in X- axis, and then use ESPRIT method to get the
arriving angle of signal in Y-axis. To avoid the time-consuming
angle searching work in the original MUSIC method, the Root-
MUSIC method is used instead. The DOA estimation algorithm is
also extended to the processing for wide-band signals. The
coherent signal subspace (CSS) and spatial resampling (SPRE)
methods are used to get proper transformations for wide-band
signals in frequency domain . After transformation, the DOA
equations of wide-band signal and narrow-band signal are
analogous with each other. Therefore, the DOA estimation method
for narrow-band signals can be adopted in estimating processes
for wide-band signals. In the derivation of estimation
algorithms, two parallel linear arrays as well as two
orthogonal linear arrays are employed. In addition to computer
simulations, experiments using hydrophone and microphone arrays
are conducted. The result show that the propsed algorithms are
feasible and efficient.
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