Direction finding networks based on the approximate maximum likelihood and covariance fit formulations

Competitive feedback network solutions for narrowband direction finding are developed. The main interest lies in estimating the directions of arrival for closely spaced sources. It is shown that if there is a priori information about the number of sources a conditional maximum likelihood solution can be obtained by the network. A suboptimal estimator that requires no a priori knowledge about the number of signals and a network that performs a covariance fit is also presented. Results are presented using both synthetic and real array data