Because the safety of the navigation depends on accurate knowledge of the submerged features, any improvements in the ability to resolve those features are of major interest. Ultimately this reflects the bottom detection performance of the bathymetric measuring system (most commonly multibeam sonar) utilized. The two most common techniques are designed around time-series or angle-series analysis, although by far the most focus has been on time-series. The newly available option of recording both amplitude and phase data of the water column permit the development and testing of new algorithms to be carried out in post-processing.

This research evaluates the use of water column data to perform bottom detection in a nonconventional way, that is, analyzing angle-series instead of time-series. The proposed algorithm is based on the BDI method with the new inclusion of phase information. Such a method, termed Phase Deviation Indicator (PDI), can be applied in an alternative and mainly complementary way to the currently existing methods.

The results obtained indicate that there are cases in which the analysis made only within a time-series, even using multi-detection features, can be incomplete and could be complemented by the analysis made within a beam-series (PDI). Particularly notable geometries included mast-like-objects, discontinuous surfaces or features whose lateral extent is confined mostly within a short range of incidence angles, thereby requiring multiple detections within the same beam. Such results emphasize the idea that the best detection method results from the integrated use of all available techniques.