Space-frequency direction finding in wideband and multi-path contexts

Over the two last decades, a great number of narrow band direction finding methods have been developed in order to estimate the DOA (directions of arrival) of impinging sources received on an array of sensors. In a radiocommunication context, the signal of each emitter propagates through different multi-path channels. In this context, the emitted signals may have various spectrum characteristics, either narrow-band with normalized frequency channels or wideband such as PN (pseudo noise) spread spectrum signals. In order to take into account these frequency and wideband characteristics we can apply a space-frequency technique as presented by Grenier et al. (1989) and by Buckley (1986) for the DOA estimation. The first purpose of this paper is to adapt these algorithms for correlated sources such as in multi-path propagation channels and the second purpose is to decrease the high computation cost of this new method by simplifying the space-frequency criterion.