< JAN 23 1990! PENNSTATE V 90 01 23 187, ABSTRACT Consider the model x(t) = As(t) + n(t), t = 1,...,N where at time t, x(t) is a p-complex vector of observations, 9(t) is a q-complex vector of unobservable signals emitted from q sources and n(t) is a noise p-complex vector variable. It is assumed that (j(t)) and The matrix A has a special structure with its k-th column Ik of the form = (1,e ...,e -2where j = ,C " , rk = c-1 Asin~k, Ok being the direction of arrival of the signal from the k-th

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... urce. The problem is the estimation of q (the number of sources) and 0i's (the directions of arrival). The paper presents an information theoretic criterion to decide on q, the number of sources, and a spectral analytic method to estimate the ri's. The proposed method is straight forward and has some advantages over the search methods proposed in the literature for the latter problem. For instance, our method works even when the signals are coherent, i.e., the covariance matrix r of signal is singular, whereas the MUSIC algorithm generally used in searching for the estimates of rk is not applicable.