“…In geophysical prospection, because of the impulsive nature of sources, the recorded signals have a strong nonstationary behavior. In order to decorrelate the signals in the interspectral matrix, several smoothing techniques have been proposed [15,16,17,18], mainly based on the spectral and spatial diversity of the signals. The drawback of spatial smoothing is the reduction of effective array-aperture length, resulting in lower resolution and accuracy, while the frequency averaging induces bias in the DOA estimates.…”