Morphological image processing for FM source detection and localization

We consider the problem of direction finding for frequency modulated 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. For the direction finding we apply beamforming techniques on averaged spatial time–frequency distribution matrices. When they occur, overlapping segments are splitted and re-combined after direction finding. The re-combination of segments is based on a bootstrap test, which resamples time–frequency auto-term locations. The proposed method also allows direction finding for the underdetermined case, i.e. when there are more sources than the number of array sensors. Furthermore, it detects the number of sources present, and the detector performance is compared to information based criteria.