Direction Finding of Nonstationary Signals using Spatial Time-Frequency Distributions and Morphological Image Processing

We consider the problem of direction finding for nonstationary signals impinging on an array of sensors. Making use of a time-frequency representation of the data, we are able to exploit the non-stationary nature of the source signals. We employ morphological image processing to estimate time-frequency signature segments of each source. Optional overlapping segments are splitted and recombined after direction finding. The proposed method also allows direction finding for the underdetermined case, i.e. when there are more sources than the number of array sensors.