Detection of objects buried in the seafloor

Buried mines threaten the Navy and also the civilian shipping routes. In order to find better countermeasures, FWG investigated the detection and classification of objects buried in the seafloor with its Experimental Sediment Sonar system (EXSESO). Because the demonstrator system is ship mounted, the experiments were close to real operational conditions at sea. The test sites are located in the Baltic Sea near Kiel. Mine like test targets of different size and shape were used. CW-pulses with a maximum bandwidth of about 5 kHz were transmitted. The center frequencies of 10 and 20 kHz meet both the requirements of penetrating into the seafloor and providing sufficient resolution. Having equipped some of the objects with a transponder, target position can be checked with high accuracy. An additional conventional sidescan sonar is attached to the EXSESO platform. This helps to separate target echos from false alarms. With the DPC-algorithm developed at the Nato Undersea Research Center (NURC), azimuth resolution of the sonar pictures could be improved.