A Parametric Approach to Extended Source Localization

Point source modeling is frequently used in m a y processing. Although this assumption is good for many applications, thm are some situations where point source modeling is unrealistic. For instance, in a multi-beam echo sounder, a reflected signal from the scs floor appears as a spatially extended source. In this paper we investigate distributed sources. The approach is based on the a ~ s u m p t i ~ that the correlation kernel of the distributed source belongs to a family of parametric functions. We generalize the MUSIC algorithm to distributed signal parameter estimator (DSPE). The DSPE locaZizer minimizes a scdar product between an estimated basis for the noise subspace and the m a y manifold. We study two cases corresponding to completely correlated and totally uncorrelated signal distributions, We also discuss limitations of the application of ordinary beamformer techniques to spatially distributed signals by computing the m a y gain. It is shown that the array gain is upper bounded by a value which depends on the extension width of the source. Thus increasing the number of the sensors in a beamformer does not necessarily increase the resolution.