An improved spatial smoothing technique for bearing estimation in a multipath environment

It is well known that signal subspace algorithms perform poorly when coherent or highly correlated signals are present. Recently, the so-called spatial smoothing technique was devised to preprocess the array covariance matrix so that signal subspace algorithms can be applied irrespective of the signal correlation. Unfortunately, the application of this technique reduces the effective aperture of the array. A modified spatial smoothing technique that is capable of increasing the effective aperture of the array over that of conventional spatial smoothing methods is explored. It is shown that under certain conditions, the modified algorithm may fail to yield the desired increase in array aperture, and some simulation results concerning the sensitivity of the modified spatial smoothing algorithm to these conditions are provided.>