*2.1. Instrument Description*

The 3D Sidescan 3DSS-DX-450 sonar system (Ping DSP) (Figure 1) uses a state-of-the-art acoustic transducer array, SoftSonar electronics, and advanced signal processing to produce superior swath bathymetry and 3D side-scan imagery. This system resolves multiple concurrent acoustic arrivals, separating backscatter from the seabed, sea surface, water column, and multipath arrivals to produce 3D side-scan image spanning the entire water column. High-resolution swath bathymetry coverage of up to 14 times altitude is achieved. The system operates on frequencies of 450 kHz and the maximum power consumption is 18 W. The dimensions of the sonar head are 57 × 9.8 cm, and its weight in air is 8 kg. The device generates a beam with a width of 0.4◦ and the maximum number of soundings per ping is 1440 across the swath [43].

**Figure 1.** Photograph of the 3D Sidescan 3DSS-DX-450 sonar system (photograph: A. Stateczny).
