Patent ID: 7436358

Claim:
A signal arrival direction estimating apparatus that estimates a direction of arrival of a signal, the apparatus comprising: a correlation matrix calculating section that calculates a noise correlation matrix in a situation where there is no signal whose direction of arrival is a target of estimation and where there is only noise, and an input signal correlation matrix in a situation where there are both a signal whose direction of arrival is a target of estimation and noise; a proper eigenvalue/proper eigenvector/improper eigenvector calculating section that calculates a proper eigenvalue, proper eigenvector and improper eigenvector of the noise correlation matrix with respect to the input signal correlation matrix, using the noise correlation matrix and the input signal correlation matrix; an arrival direction estimating section that estimates the direction of arrival of the signal based on the proper eigenvalue, the proper eigenvector and the improper eigenvector; and a section for, in the case of the signal subspace not orthogonal to the noise subspace, nullifying the correlation of the noise.