Estimating the directions of arrival based on multi-subarray subspace fitting

A multi-subarray subspace fitting method which take mutual coupling among array elements into account to estimate the directions of arrival was presented. The mutual coupling matrix of uniform linear arrays is modeled with a banded symmetric Toeplitz matrix. According to the DOF (Degree of Freedom) of mutual coupling matrix, part of the array elements at the two sides are neglected. The theoretical characteristics of ESPRIT algorithm, one of the subspace fitting algorithms, are studied. For large N and uniform linear array, the MCLS ESPRIT estimation error is asymptotically jointly Gaussian distributed with zero means, and its covariance expression is obtained. It is known from the simulation that there exists a subarray with lowest estimation error for certain number of the array elements and the signal sources, and its performance of estimating the directions of arrival is close to the ideal situation when mutual coupling does not exist while its variance has some increase. The method has been applied to bathymetric sidescan sonar with high resolution, and good results have been obtained. At the cost of increasing the number of the array elements, the method can reduce the affection of the mutual coupling among array elements.

Estimating the directions of arrival based on multi-subarray subspace fitting