An approximate maximum likelihood method for estimation of direction of arrival parameters

The estimation of DOA and associated signal parameters from the observations received by isotropic sensors in additive noise medium is considered. The DOAs and signal parameters to be estimated are functions of number of snapshots (N), number of sensors(M), signal-to-noise ratio (SNR), separation, φ_d and correlation between the sources, ϑ. Different criterion functions for low and for high SNR are obtained by suitable approximations choosing relevant terms depending upon the nature of the parameters. In the first step, expressions are derived for the estimates of the signal power (spectral density in the wideband instance) and noise power. In step two, these are used to estimate the DOA angles. Simulation results for narrowband signals show the performance of the proposed method. The estimation approach could be extended for wideband signals