Abstract
Aiming at the two-dimensional (2D) incoherently distributed (ID) sources, we explore a direction-of-arrival (DOA) estimation algorithm based on uniform rectangular arrays (URA). By means of Taylor series expansion of steering vector, rotational invariance relations with regard to nominal azimuth and nominal elevation between subarrays are deduced under the assumption of small angular spreads and small sensors distance firstly; then received signal vectors can be described by generalized steering matrices and generalized signal vectors; thus, an estimation of signal parameters via rotational invariance techniques (ESPRIT) like algorithm is proposed to estimate nominal elevation and nominal azimuth respectively using covariance matrices of constructed subarrays. Angle matching method is proposed by virtue of Capon principle lastly. The proposed method can estimate multiple 2D ID sources without spectral searching and without information of angular power distribution function of sources. Investigating different SNR, sources with different angular power density functions, sources in boundary region, distance between sensors and number of sources, simulations are conducted to investigate the effectiveness of the proposed method.
Highlights
In most applications of array signal processing, traditional DOA estimation is based on point source models which can simplify calculations
We propose an estimator for 2D incoherently distributed (ID) sources using uniform rectangular arrays (URA)
The received signal vectors can be transformed as combinations of generalized signal vectors and generalized steering matrices can be transformed as combinations of generalized signal vectors and generalized steering matrices through Taylor series expansions
Summary
In most applications of array signal processing, traditional DOA estimation is based on point source models which can simplify calculations. Point source models assume that propagations between sources and receive arrays are straight paths and the spatial characteristics of sources can be ignored. In the real surrounding of underwater, on the one hand, there exist paths from seabed and sea surface of backscatters; on the other hand, spatial scatterers of targets cannot be ignored when the distances from targets and receive arrays are short. The signal of a source only propagates from a single direction through a straight path under the assumption of point source model. Spatial distribution of a distributed source can be generally modeled as Gaussian or uniform with parameters containing nominal angles and angular spreads. Nominal angles represent the center of targets and angular spreads represent the spatial extension of targets
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